tag:theconversation.com,2011:/global/topics/sweat-4859/articlesSweat – The Conversation2023-06-20T09:33:09Ztag:theconversation.com,2011:article/1983422023-06-20T09:33:09Z2023-06-20T09:33:09ZIs hot yoga good for you? Exploring the science behind the sweat<iframe id="noa-web-audio-player" style="border: none" src="https://embed-player.newsoveraudio.com/v4?key=x84olp&id=https://theconversation.com/is-hot-yoga-good-for-you-exploring-the-science-behind-the-sweat-198342&bgColor=F5F5F5&color=D8352A&playColor=D8352A" width="100%" height="110px"></iframe>
<p><a href="https://theconversation.com/yoga-isnt-timeless-its-changing-to-meet-contemporary-needs-97162">Hot yoga</a> also known as <a href="https://www.yoga-society.com/blogs/types-of-yoga/what-is-bikram-yoga">Bikram yoga</a> (more on that later) has <a href="https://www.cnet.com/health/fitness/benefits-of-hot-yoga/">gained significant popularity in recent years</a> as a fairly ferocious form of exercise. It combines yoga poses and breathing exercises and is practised in a heated studio – with room temperatures close to 40°C.</p>
<p>This style of yoga is designed to replicate the environmental conditions of India and is typically practised for around 90 minutes, leaving students (and teachers) dripping in sweat come the end of class.</p>
<p>Practising hot yoga challenges the mind and places additional physiological strain on the body. It makes you very sweaty and increases your heart rate, which can feel pretty intense. Indeed, hot yoga can lead to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5433110/">dehydration and dizziness</a>, especially if it’s your first time and you don’t begin the class hydrated.</p>
<p>Designed to develop strength, flexibility and balance, hot yoga is believed to offer enhanced physical and <a href="https://journals.copmadrid.org/pi/art/pi2022a4">mental health benefits</a> – including improved levels of fitness and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609431/">reduced stress levels</a>. </p>
<p>But it can also feel uncomfortable – think sweat trickling into your eyes while doing a headstand – and hard going: with fast, dynamic sequences repeated numerous times. Then there are also those tricky balances and multiple lunges, all done at high temperatures, meaning that at times classes can feel pretty gruelling.</p>
<p>So are all these hot sweaty postures actually any good for you? Let’s take a look at the science. </p>
<h2>The origins of hot yoga</h2>
<p>Before we go into the evidence, a bit on the history. Originally known as “<a href="https://www.shape.com/fitness/workouts/things-you-need-know-about-bikram-yoga">Bikram yoga</a>”, named after its creator Bikram Choudhury, the traditional style of hot yoga was developed in the early 1970s. It involves a series of 26 fixed postures, carried out over 90 minutes while experiencing extreme heat stress. </p>
<p>In recent years many yoga studios have chosen to <a href="https://www.theguardian.com/tv-and-radio/2019/dec/03/he-made-a-fortune-from-his-trademarked-bikram-yoga-but-now-his-empire-is-in-tatters">rebrand</a> these classes as “hot yoga”, having changed from the original 26 fixed postures to be more flowing and individual and to include music (which Bikram classes don’t). </p>
<p>Another reason many yoga studios have chosen to <a href="https://www.huffingtonpost.co.uk/entry/bikram-choudhury-sexual-assault_n_5d4dc527e4b0fd2733f0286f">move away from the Bikram style</a> of yoga is that <a href="https://www.theguardian.com/lifeandstyle/2017/feb/18/bikram-hot-yoga-scandal-choudhury-what-he-wanted">multiple women</a> have <a href="https://www.independent.co.uk/life-style/bikram-choudhury-yoga-rape-sexual-abuse-netflix-documentary-who-a9210771.html">come forward</a> with <a href="https://www.vogue.in/culture-and-living/content/bikram-hot-yoga-controversy-bikram-choudhury-sexual-assault-netflix-documentary">accusations of sexual harassment</a> and <a href="https://www.theguardian.com/film/2019/nov/20/bikram-choudhury-yoga-founder-abuse-netflix-documentary">assault against Choudhury</a>. This has led to <a href="https://www.latimes.com/local/lanow/la-me-ln-bikram-yoga-lawsuit-20160126-story.html">legal action</a> and been the focus of a 2019 Netflix documentary: <a href="https://www.netflix.com/gb/title/80221584">Bikram: Yogi, Guru, Predator</a>.</p>
<p>Even before the <a href="https://www.refinery29.com/en-gb/2019/11/8874728/bikram-yoga-founder-scandal-new-netflix-documentary">Bikram scandal</a>, not everyone in the yoga community backed the idea of hot yoga. This is because traditional yoga practice involves a series of postures known as sun salutations, which are performed early in the morning (when it’s cooler), not during the midday heat. </p>
<h2>What the science says</h2>
<p>Although <a href="https://hfjc.library.ubc.ca/index.php/HFJC/article/view/220">comprehensive scientific reviews</a> are <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609431/">still lacking</a>, some studies have indicated potential health benefits from hot yoga. Modified Bikram yoga performed regularly has been <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609431/">associated with</a> increased aerobic fitness and improved cardiovascular function. </p>
<p>Hot yoga has <a href="https://journals.lww.com/nsca-jscr/Fulltext/2018/10000/Efficacy_of_Hot_Yoga_as_a_Heat_Stress_Technique.23.aspx">shown promise</a> in terms of <a href="https://www.liebertpub.com/doi/full/10.1089/acm.2012.0709">heart health</a>, by lowering “bad cholesterol” levels and <a href="https://pubmed.ncbi.nlm.nih.gov/24138995/">improving glucose tolerance</a>. Glucose intolerance may indicate an increased risk of metabolic conditions, such as diabetes.</p>
<p>It has <a href="https://journals.lww.com/nsca-jscr/fulltext/2013/03000/bikram_yoga_training_and_physical_fitness_in.35.aspx?casa_token=6VxlqbNhg6YAAAAA:Q1t8bes2-X1blvLrO0vMe7AdpxJyZ4xtU69WSWoLbTtwTb7kHur2Lv5XjeIsy7OIRntbCb5Le1ciqCsWq60MElzJaEqJWDQ">also been linked</a> to an increase in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609431/">strength</a>, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7241641/">flexibility</a> <a href="https://scielo.isciii.es/pdf/inter/v31n2/1132-0559-inter-31-2-0067.pdf">and enhanced mental health</a>, including improved stress management and sleep quality.</p>
<figure class="align-center ">
<img alt="Women in hot yoga studio sweating." src="https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531979/original/file-20230614-21-cbnbgo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Getting a sweat on for that mind-body connection.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fitness-asian-female-group-doing-namaste-527129368">Southtownboy Studio/Shutterstock</a></span>
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<p>Yoga is classified as a “light-intensity exercise” by the <a href="http://www.alternative-therapies.com/openaccess/ATHM_20_4_pate.pdf">American College of Sports Medicine</a> but <a href="https://www.researchgate.net/profile/Rajasree-Nambron-2/publication/281017791_Unilateral_spontaneous_adrenal_hemorrhage_in_pregnancy/links/55d14c3a08ae6a881385ec32/Unilateral-spontaneous-adrenal-hemorrhage-in-pregnancy.pdf#page=6">studies</a> show that hot yoga sessions can result in high heart rates, increased core temperatures of 38˚C-40˚C and substantial sweat losses – <a href="https://pubmed.ncbi.nlm.nih.gov/33230967/">up to 1.5 litres per session</a> – making it a more <a href="https://cdnsciencepub.com/doi/abs/10.1139/apnm-2017-0495">intense exercise</a>.</p>
<p>When it comes to hot yoga classes, <a href="https://www.lboro.ac.uk/microsites/lds/EEC/ICEE/textsearch/13proceedings/Environmental%20Ergonomics%20XV_Proceedings%20for%20Webpage_V1.pdf#page=153">research</a> has also found that novices and experienced practitioners exhibit similarities in heart rate but can differ in sweat rate and core temperature changes. The more experienced you are, the more you sweat and the hotter you may get. This is likely because more experienced hot yogis will be better adapted to the heat and so able to push harder.</p>
<p>It’s often claimed that practising yoga in a heated environment may help with “<a href="https://www.yogajournal.com/practice/does-yoga-detox-your-body/">detoxification</a>” and the release of <a href="https://www.cbsnews.com/news/reality-check-yoga-does-not-release-toxins-from-the-body/">toxins from the body</a> due to excessive sweating. But this is rubbish – that’s what our kidneys are for. The reality is that those who practice hot yoga will probably lose more <a href="https://physoc.onlinelibrary.wiley.com/doi/full/10.14814/phy2.14647#:%7E:text=Abstract,cation%20of%20the%20extracellular%20fluid.">sodium</a> (or salt) and so are more likely to become dehydrated through increased sweat loss compared to yoga in cooler conditions. </p>
<p>Given this, hot yoga may be of benefit to those wishing to adapt to heat stress. For example, athletes preparing for elite sports such as <a href="https://pubmed.ncbi.nlm.nih.gov/29979281/">hockey</a> – if performed safely. </p>
<h2>And the risks?</h2>
<p>Because hot yoga can be physically demanding, <a href="https://www.hindawi.com/journals/ecam/2015/428427/">it may not be suitable for everyone</a>, especially for those with certain medical conditions or sensitivity to heat. Plus, some of the research looking at the benefits of hot yoga <a href="https://pubmed.ncbi.nlm.nih.gov/22592178/">hasn’t been replicated</a> – essentially meaning that further investigations are required to fully understand the true value of hot yoga in terms of physical fitness.</p>
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<p>So while it does seem that there are some potential benefits, it’s important to be mindful of the potential risks associated with hot yoga, too. The heated environment, for example, can increase the risk of dehydration, heat exhaustion and potentially heat stroke, especially if <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5433110/">proper hydration practices</a> are not followed.</p>
<p>People with certain medical conditions, such as heart disease or high blood pressure, or those who are pregnant may need to exercise caution or consult their doctor before participating in hot yoga. And it’s vital that students listen to their bodies, take breaks when needed and stay hydrated throughout their practice.</p>
<p>With hot and humid conditions, on top of excessive sweating, hygiene and cleanliness is also important for you and your mat. So don’t forget your towel and wipe your mat down afterwards too.</p><img src="https://counter.theconversation.com/content/198342/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Sweating it out can be beneficial for maintaining fitness and good mental health, but it’s not right for everyone.Ash Willmott, Senior Lecturer in Sport and Exercise Science, Anglia Ruskin UniversityJessica Mee, Senior Lecturer in Sport and Exercise Science, University of WorcesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1990852023-02-10T01:50:05Z2023-02-10T01:50:05ZIs my medicine making me feel hotter this summer? 5 reasons why<figure><img src="https://images.theconversation.com/files/508796/original/file-20230208-24-lf74uh.jpg?ixlib=rb-1.1.0&rect=2%2C1%2C995%2C664&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/overheated-woman-sitting-on-couch-waving-1707953323">Shutterstock</a></span></figcaption></figure><p>If you’re really feeling the heat this summer, it might be down to more than the temperature outside.</p>
<p>Some types of medicines can increase your core body temperature or make you feel hotter than you really are. Some can affect your body’s ability to cool down.</p>
<p>Here’s what you need to know about heat intolerance and medicines.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-cope-with-extreme-heat-days-without-racking-up-the-aircon-bills-128857">How to cope with extreme heat days without racking up the aircon bills</a>
</strong>
</em>
</p>
<hr>
<h2>What is heat intolerance?</h2>
<p>Some people simply dislike the feeling of feeling hot, while others feel hot at temperatures most people find comfortable. Both are examples of
<a href="https://www.medicalnewstoday.com/articles/325232#symptoms">heat intolerance</a>.</p>
<p>Typical symptoms during warm weather include excessive sweating (or not sweating enough), exhaustion and fatigue, nausea, vomiting or dizziness, and changes in mood.</p>
<p>A number of factors can cause heat intolerance.</p>
<p>This includes the disorder <a href="https://my.clevelandclinic.org/health/diseases/6004-dysautonomia">dysautonomia</a>, which affects people’s autonomic nervous system – the part of the body that regulates the automatic functions of the body, including our response to heat. </p>
<p>Conditions such as diabetes, alcohol misuse, <a href="https://theconversation.com/what-causes-parkinsons-disease-what-we-know-dont-know-and-suspect-57579">Parkinson’s disease</a>, the autoimmune disease <a href="https://theconversation.com/explainer-what-is-guillain-barre-syndrome-and-is-it-caused-by-the-zika-virus-53884">Guillain-Barré syndrome</a> and <a href="https://theconversation.com/explainer-what-are-mitochondria-and-how-did-we-come-to-have-them-83106">mitochondrial disease</a> can cause dysautonomia. People in old age, those with some neurological conditions, or people less physically fit may also have it.</p>
<p>But importantly, medications can also contribute to heat intolerance.</p>
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<p>
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Read more:
<a href="https://theconversation.com/5-reasons-to-check-on-your-elderly-neighbour-during-a-heatwave-196218">5 reasons to check on your elderly neighbour during a heatwave</a>
</strong>
</em>
</p>
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<h2>1. Your body temperature rises</h2>
<p>Some medicines directly increase your body temperature, which then increases the risk of heat intolerance. </p>
<p>These include <a href="https://bpspubs.onlinelibrary.wiley.com/doi/epdf/10.1111/bph.15465">stimulant medications</a> to treat ADHD (attention deficit hyperactivity disorder), such as methylphenidate, dexamfetamine and lisdexamfetamine.</p>
<p><a href="https://www.healthdirect.gov.au/antipsychotic-medications">Antipsychotic medications</a> (such as clozapine, olanzapine and quetiapine) used to treat mental health conditions, such as schizophrenia and bipolar disorder, are other examples. </p>
<p>These ADHD and antipsychotic medicines raise your temperature by acting on the hypothalamus, the region of the brain essential for cooling.</p>
<p>The drug levothyroxine, used to treat an under-active thyroid, also increases your body temperature, this time by <a href="https://www.ncbi.nlm.nih.gov/books/NBK500006/">increasing your metabolism</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/508840/original/file-20230208-28-ki6965.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Medical illustration of hypothalamus region of brain" src="https://images.theconversation.com/files/508840/original/file-20230208-28-ki6965.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/508840/original/file-20230208-28-ki6965.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/508840/original/file-20230208-28-ki6965.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/508840/original/file-20230208-28-ki6965.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/508840/original/file-20230208-28-ki6965.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/508840/original/file-20230208-28-ki6965.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/508840/original/file-20230208-28-ki6965.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Some medicines raise your body temperature directly by acting on the hypothalamus region of the brain.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/3d-rendered-medically-accurate-illustration-hypothalamus-1292650669">SciePro/Shutterstock</a></span>
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<h2>2. Your blood flow is affected</h2>
<p>Other medicines constrict (tighten) blood vessels, decreasing blood flow to the skin, and so prevent heat from escaping this way. This means your body can’t regulate its temperature as well in the heat. </p>
<p>Examples include <a href="https://www.healthdirect.gov.au/beta-blockers">beta-blockers</a> (such as metoprolol, atenolol and propranolol). These medications are used to treat conditions such as high blood pressure, angina (a type of chest pain), tachycardia (fast heart rate), heart failure, and to prevent migraines. </p>
<p><a href="https://www.nhs.uk/conditions/decongestants/">Decongestants</a> for blocked noses (for example, pseudoephedrine and phenylephrine), triptans for migraines (such as sumatriptan and zolmitriptan) and the ADHD medications mentioned earlier can also act to decrease blood flow to the skin.</p>
<hr>
<p>
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</strong>
</em>
</p>
<hr>
<h2>3. You can get dehydrated</h2>
<p>Other medicines can cause dehydration, which then makes you more susceptible to heat intolerance. The best examples are <a href="https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/in-depth/diuretics/art-20048129">diuretics</a> such as furosemide, hydrochlorothiazide, acetazolamide and aldosterone.</p>
<p>These are used to control high blood pressure and heart failure by forcing your kidneys to remove more fluid from your body. </p>
<p>Laxatives, such as senna extract and bisacodyl, also remove water from your body and so have a similar effect.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-how-do-i-tell-if-im-dehydrated-107437">Health Check: how do I tell if I'm dehydrated?</a>
</strong>
</em>
</p>
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<h2>4. You can sweat less</h2>
<p>Other medicines have a drying effect. This can be needed for medicines to do their job (for instance, to dry up a runny nose). For others, it is an unwanted side effect. </p>
<p>This drying reduces the amount you sweat, making it harder to lose heat and regulate your core temperature. A number of medicines have these effects, including:</p>
<ul>
<li>some antihistamines (such as promethazine, doxylamine and diphenhydramine)</li>
<li>certain antidepressants (such as amitriptyline, clomipramine and dothiepin)</li>
<li>medicines used to treat <a href="https://www.healthdirect.gov.au/urinary-incontinence#:%7E:text=Urinary%20incontinence%2C%20or%20poor%20bladder%20control%2C%20is%20very%20common%20in,to%20cure%20or%20improve%20it.">urinary incontinence</a> (for example, oxybutynin and solifenacin) </li>
<li>nausea medicine (prochlorperazine)</li>
<li>medicines for stomach cramps and spasms (for instance, hyoscine) </li>
<li>the antipsychoptics chlorpromazine, olanzapine, quetiapine and clozapine.</li>
</ul>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-do-men-really-sweat-more-than-women-73903">Health Check: do men really sweat more than women?</a>
</strong>
</em>
</p>
<hr>
<h2>5. You don’t feel thirsty</h2>
<p>Finally, some medicines, such as the antipsychotics haloperidol and droperidol, can aggravate heat intolerance by reducing your ability to feel thirsty. </p>
<p>If you don’t feel thirsty, you drink less and are therefore at risk of dehydration and feeling hot.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/508849/original/file-20230208-31-oak7ni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Woman staring at glass of water on counter" src="https://images.theconversation.com/files/508849/original/file-20230208-31-oak7ni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/508849/original/file-20230208-31-oak7ni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/508849/original/file-20230208-31-oak7ni.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/508849/original/file-20230208-31-oak7ni.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/508849/original/file-20230208-31-oak7ni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/508849/original/file-20230208-31-oak7ni.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/508849/original/file-20230208-31-oak7ni.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">People taking some medications just don’t feel thirsty.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/upset-young-woman-looking-through-glass-754782025">Shutterstock</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-how-can-extreme-heat-lead-to-death-91480">Health Check: how can extreme heat lead to death?</a>
</strong>
</em>
</p>
<hr>
<h2>What can you do about it?</h2>
<p>If you are feeling hot this summer and think your medicine may be contributing, it’s very important you keep taking your medicine.</p>
<p>Speak to your pharmacist or doctor about your symptoms. They will offer advice and discuss alternatives.</p><img src="https://counter.theconversation.com/content/199085/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Associate Professor Wheate in the past has received funding from the ACT Cancer Council, Tenovus Scotland, Medical Research Scotland, Scottish Crucible, and the Scottish Universities Life Sciences Alliance. He is a Fellow of the Royal Australian Chemical Institute, a member of the Australasian Pharmaceutical Science Association, and a member of the Australian Institute of Company Directors. Nial is the chief scientific officer of Vairea Skincare LLC and a Standards Australia panel member for sunscreen agents.</span></em></p><p class="fine-print"><em><span>Jessica Pace does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>If you think your medicine may be contributing to overheating, it’s very important you keep taking your medicine. Discuss your symptoms with your pharmacist or doctor.Nial Wheate, Associate Professor of the Sydney Pharmacy School, University of SydneyJessica Pace, Associate Lecturer, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1845612022-08-17T04:09:20Z2022-08-17T04:09:20ZWhy do my feet smell? And what can I do about it?<figure><img src="https://images.theconversation.com/files/479559/original/file-20220817-20-7olb0l.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1000%2C666&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>“Smelly” might be the first word that comes to mind when you think of feet.</p>
<p>Why do some people’s feet have no smell, yet other feet are so pungent they could almost <a href="https://youtu.be/jAT4zNSB838">knock you out</a>? </p>
<p>Let’s go through what causes smelly feet, what you can do about it, and when to seek professional advice.</p>
<h2>Sweaty feet</h2>
<p>Sweaty feet can lead to smelly feet.</p>
<p>Feet can become sweaty in hot weather, especially if we wear a closed-in shoe or boot and the sweat doesn’t evaporate.</p>
<p>Anxiety and emotional stress also increase the <a href="https://psychcentral.com/anxiety/anxiety-sweat#link">activity</a> of sweat glands due to the release of stress hormones such as adrenaline, causing sweaty hands and feet. </p>
<p>Sweaty feet are common, but some people have an excessive sweating condition called “<a href="https://www.racgp.org.au/afp/2013/may/hyperhidrosis-and-bromhidrosis">hyperhidrosis</a>”. It’s very distressing and can lead to social awkwardness, reduced self-confidence and poor mental health. </p>
<p>But sweat usually doesn’t have a smell by itself. It’s the bacteria that feast on sweat that cause the bad smell.</p>
<h2>Bacteria and sweat</h2>
<p>Humans have around 1,000 species of <a href="https://health.howstuffworks.com/wellness/men/sweating-odor/bacteria-cause-body-odor.htm">bacteria</a> living on our skin. Bacteria thrive in moist environments such as our armpits, groin and also in between our toes. The bacteria living on our skin are mostly harmless (and some are even good for us), but they can also cause odour when they interact with sweat.</p>
<p><a href="https://pubmed.ncbi.nlm.nih.gov/16699586/">Foot odour</a> is associated with several types of bacteria. When these bacteria eat the sugars and fats in sweat, they produce chemicals with a <a href="https://www.bing.com/videos/search?q=why+does+my+body+smell+you+tube&view=detail&mid=A840EA2AFFA0616EB2F5A840EA2AFFA0616EB2F5&FORM=VIRE">noxious smell</a>. </p>
<p>The most common chemical compounds are:</p>
<ul>
<li><p>“isovaleric acid”, which has a distinctive cheesy, sweaty feet <a href="https://www.discovermagazine.com/planet-earth/bacteria-give-feet-4-distinct-odors">odour</a></p></li>
<li><p>“propionic acid”, which <a href="https://www.healthline.com/health/feet-smell-like-vinegar#:%7E:text=Foot%20sweat%20on%20some%20people,odor%20that%20smells%20like%20vinegar.">smells sour</a>. </p></li>
</ul>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-do-my-armpits-smell-and-would-using-glycolic-acid-on-them-really-work-183354">Why do my armpits smell? And would using glycolic acid on them really work?</a>
</strong>
</em>
</p>
<hr>
<p>A type of bacteria called “<a href="https://thecheesewanker.com/cheese-science/why-some-cheeses-smell-like-feet/#:%7E:text=Brevibacterium%20linens%3A%20The%20bacteria%20behind%20it%20all%20The,a%20harmless%20bacterium%20that%20lives%20on%20our%20skin.">brevibacteria</a>” also cause foot odour. They eat dead skin on our feet, producing a gas which has a distinctive sour smell.</p>
<p><a href="https://thecheesewanker.com/cheese-science/why-some-cheeses-smell-like-feet/#:%7E:text=Brevibacterium%20linens%3A%20The%20bacteria%20behind%20it%20all%20The,a%20harmless%20bacterium%20that%20lives%20on%20our%20skin.">Cheesemakers</a> will often add this bacteria to the surface of cheese to develop texture and flavour. This explains why many cheeses smell like feet, and feet smell like cheese!</p>
<p>Biologist Bart Knols received an “Ig Nobel” Prize (for unusual scientific achivements) in 2006 for demonstrating that a type of mosquito known for transmitting malaria has an equal preference for <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(05)65812-6/fulltext">Limburger cheese</a> and the smell of human feet.</p>
<figure class="align-center ">
<img alt="Woman smells man's smelly feet" src="https://images.theconversation.com/files/479087/original/file-20220815-20-73f28m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/479087/original/file-20220815-20-73f28m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/479087/original/file-20220815-20-73f28m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/479087/original/file-20220815-20-73f28m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/479087/original/file-20220815-20-73f28m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/479087/original/file-20220815-20-73f28m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/479087/original/file-20220815-20-73f28m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">There’s a reason feet sometimes smell like cheese.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>What else can cause smelly feet?</h2>
<p>Foot odour is made worse by socks and shoes that don’t allow sweat to evaporate from the skin. When sweat can’t evaporate from the skin, the temperature and relative humidity rise inside footwear, particularly in shoes such as <a href="https://www.researchgate.net/publication/303487588_THE_MICROCLIMATE_IN_PROTECTIVE_FIRE_FIGHTER_FOOTWEAR_FOOT_TEMPERATURE_AND_AIR_TEMPERATURE_AND_RELATIVE_HUMIDITY">work boots</a>.
Bacteria prefer a warm, damp environment.</p>
<p>A bacterial skin infection called “<a href="https://dermnetnz.org/topics/pitted-keratolysis">pitted keratolysis</a>” may also cause bad foot odour. It typically affects the soles of the feet and in between toes, and makes the skin white and soggy, often with clusters of small punched-out craters or “pits”. These pits are caused by bacteria digesting the skin and producing sulphur compounds. </p>
<p>It’s more common in men than women and is associated with sweaty feet, poor foot hygiene, diabetes and <a href="https://dermnetnz.org/topics/immunodeficiency">immunodeficiency</a>. Pitted keratolysis will respond to <a href="https://dermnetnz.org/topics/pitted-keratolysis">treatment</a> with antiseptic agents and topical antibiotics.</p>
<p>Foot odour can also be caused by tinea, a fungal skin infection often called athlete’s foot, which a podiatrist will be able to diagnose. It can be treated with an anti-fungal cream or lotion. </p>
<h2>What you can do to manage sweaty and smelly feet</h2>
<p>The first things to consider if you have smelly feet are foot hygiene and footwear. </p>
<p>Feet don’t wash themselves in the shower. In fact, bacteria from the rest of your body are washed down to your feet. So, it’s important to wash your feet with soap – including between your toes!</p>
<p>Drying your feet thoroughly after bathing is also important to prevent the build-up of sweat and bacteria.</p>
<p>It’s ideal to alternate your footwear so that shoes and boots have a chance to dry out before you wear them again. Damp footwear is the perfect place for bacteria to thrive and create those smelly chemicals.</p>
<p>Regular washing and drying of anything your wear on your feet will remove bacteria and stale sweat.</p>
<p>Bamboo has a natural antimicrobial effect (meaning it may have some ability to slow bacteria or mould growing), and socks made from this fibre <a href="https://www.tandfonline.com/doi/abs/10.1080/00405000.2011.614742">may be helpful</a>, but it’s <a href="https://consumer.ftc.gov/articles/bamboo-fabrics">unclear</a> whether the benefits <a href="http://mistrafuturefashion.com/bamboo-fibers-anti-bacterial-quality-a-misconception/">translate to bamboo clothing products</a>.</p>
<p>There’s <a href="https://www.taylorfrancis.com/chapters/edit/10.1201/9781003141426-4/axillary-odour-formation-retention-role-textiles-fibers-fabric-structure-rathinamoorthy-thilagavathi">conflicting</a> <a href="https://www.sciencedirect.com/science/article/pii/S1110016818301327">views</a> <a href="https://www.researchgate.net/publication/342480090_Influence_of_Moisture_Management_Properties_on_Socks_Made_from_Recycled_Polyester_Virgin_Cotton_and_its_Blends_FIBRES_TEXTILES_in_Eastern">on</a> the best material for shoes and socks to improve smelly feet, so more research is needed. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1519552835553468416"}"></div></p>
<h2>Treatments for sweaty and smelly feet</h2>
<p>If your feet are stubbornly sweaty and smelly even with good foot hygiene and attention to footwear, you may need to consider some other options.</p>
<p>An expert opinion from a podiatrist will help you make an appropriate treatment choice and ensure more serious issues aren’t missed.</p>
<p>Most of the available treatments for body odour target sweat production:</p>
<ul>
<li><p>a strong <a href="https://www.racgp.org.au/afp/2013/may/hyperhidrosis-and-bromhidrosis">antiperspirant</a> containing aluminium chloride hexhydrate, which can be purchased from a pharmacy without a prescription and applied directly to your feet </p></li>
<li><p>“<a href="https://dermnetnz.org/topics/iontophoresis">iontophoresis</a>” is a procedure offered at specialist clinics to reduce sweating in the hands and feet. A mild electrical current is passed through skin soaked in tap water. <a href="https://dermnetnz.org/topics/iontophoresis">One study</a> found around 75–80% of participants had reduced foot sweating after 20 days of this treatment</p></li>
<li><p><a href="https://www.racgp.org.au/afp/2013/may/hyperhidrosis-and-bromhidrosis">Botox</a> treatments are highly effective in reducing foot sweating. Botox works by blocking the nerves that activate sweat glands. However, injections into the sole of your foot can be very uncomfortable</p></li>
<li><p>a topical cream containing a small amount of “glycopyrronium bromide” <a href="https://dermnetnz.org/topics/anticholinergic-medications">can help</a> to control excessive sweating.</p></li>
</ul>
<hr>
<p><em>Caroline Robinson would like to thank Anna Horn from Charles Sturt podiatry, for her contribution to researching this article.</em></p><img src="https://counter.theconversation.com/content/184561/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Caroline Robinson is affiliated with the Australasian Council of Podiatry Deans and the Australian Podiatry Association.
She'd like to thank Anna Horn from Charles Sturt podiatry, for her contribution to researching this article.</span></em></p>Fresh sweat doesn’t have a smell. It’s the bacteria that feast on sweat that cause the bad smell.Caroline Robinson, Associate Professor Podiatry, Charles Sturt UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1876552022-08-01T12:26:47Z2022-08-01T12:26:47ZHow to keep high school athletes safe from heat illness in a brutally hot summer<figure><img src="https://images.theconversation.com/files/475877/original/file-20220725-21-xc8tzu.jpg?ixlib=rb-1.1.0&rect=17%2C27%2C2268%2C1510&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Staying hydrated is part of staying safe during summer workouts.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/james-opio-and-lucas-harbaugh-in-background-drink-some-news-photo/1025049102">Shawn Patrick Ouellette/Portland Portland Press Herald via Getty Images</a></span></figcaption></figure><p><em>As temperatures rise, heat illnesses are becoming an increasing risk for athletes, particularly in the first few weeks of practice. <a href="https://scholar.google.com/citations?user=PrD8j0oAAAAJ&hl=en">Susan Yeargin</a>, an associate professor of athletic training at the University of South Carolina and co-author of the National Athletic Trainers Association’s <a href="https://doi.org/10.4085/1062-6050-50.9.07">position statement on heat illness</a>, explains the risks and what coaches and players need to remember to keep kids safe.</em></p>
<h2>Why are athletes particularly vulnerable to heat during the first few weeks of training?</h2>
<p>When an athlete of any age begins to exercise or train for a sport in hot conditions, the body needs time to adapt. In a natural outdoor environment, this is called heat acclimatization.</p>
<p>In the first three days of heat exposure, the body hasn’t started to adapt, which is why those are <a href="https://doi.org/10.4085/1062-6050-542-18">the riskiest days</a> for heat illness. Most acclimatization happens by the 10th day, but it takes <a href="https://doi.org/10.4085/1062-6050-50.9.07">about two weeks</a> for the body to reach its peak heat acclimatization.</p>
<figure class="align-center ">
<img alt="High school football players in shorts and minimal pads at a summer practice." src="https://images.theconversation.com/files/476738/original/file-20220729-7118-pcmrpl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476738/original/file-20220729-7118-pcmrpl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476738/original/file-20220729-7118-pcmrpl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476738/original/file-20220729-7118-pcmrpl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476738/original/file-20220729-7118-pcmrpl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476738/original/file-20220729-7118-pcmrpl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476738/original/file-20220729-7118-pcmrpl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">There are good reasons that players start the first few weeks of preseason practice slowly.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/during-a-muhlenberg-high-school-football-team-heat-news-photo/1333572436">Ben Hasty/MediaNews Group/Reading Eagle via Getty Images</a></span>
</figcaption>
</figure>
<p>The most important change within the body is <a href="https://doi.org/10.3389/fphys.2019.01379">plasma volume expansion</a>, giving the body more blood to help dissipate heat and supply exercising muscles. In short, it allows the cardiovascular system to work more efficiently. </p>
<p>The <a href="https://doi.org/10.1016/j.jtherbio.2020.102697">rate of sweating</a> also increases, allowing more heat to dissipate from the body. The body increases its retention of salt, which is good because it allows for better electrolyte balance within the body to maintain hydration and keep muscles working optimally. The heart rate decreases, so there is less strain on the cardiovascular system. And the core body temperature decreases, representing a lower risk for exertional heat stroke.</p>
<p>But even with all of these adaptations, the body isn’t fully protected from heat illness, which is why other prevention strategies are needed.</p>
<p>Also, just because athletes have been training over the summer doesn’t mean they are fully adapted to heat under the conditions that a sport season imposes. The sports season brings new exercise intensity, often higher heat than earlier in the summer, and heavier equipment, like pads and helmets, and an increased pressure to perform.</p>
<h2>At what point do temperatures start getting dangerous for young athletes?</h2>
<p>That <a href="https://ksi.uconn.edu/prevention/wet-bulb-globe-temperature-monitoring/">varies across the country</a>. Athletes who live in milder climates should not be practicing in environmental conditions over 86.2 degrees Fahrenheit (30.1 degrees Celsius), based on <a href="https://www.weather.gov/tsa/wbgt">wet bulb globe temperature</a>. For those in traditionally hotter climates, like Texas, the recommended cutoff temperature for canceling practice is 92 F (32.2 C).</p>
<p>The risk is about more than the temperature – it’s also about humidity, sun and wind. Humidity hinders sweat evaporation, the body’s primary heat dissipation mechanism. So when humidity is high, no matter the air temperature, that creates a heat safety concern.</p>
<figure class="align-center ">
<img alt="A young man with a bag of ice on his head." src="https://images.theconversation.com/files/476737/original/file-20220729-18-j81vln.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476737/original/file-20220729-18-j81vln.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=358&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476737/original/file-20220729-18-j81vln.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=358&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476737/original/file-20220729-18-j81vln.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=358&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476737/original/file-20220729-18-j81vln.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=450&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476737/original/file-20220729-18-j81vln.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=450&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476737/original/file-20220729-18-j81vln.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=450&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An athlete cools off in California during an August practice.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/norco-high-football-player-takes-a-break-from-practice-to-news-photo/1235000496">Terry Pierson/MediaNews Group/The Press-Enterprise via Getty Images</a></span>
</figcaption>
</figure>
<p>Athletic trainers often use wet bulb globe temperature – which takes all four of those variables into account – to determine when teams should shorten or cancel practice and how often rest and cooling breaks should be required. It’s a better gauge of risk than the heat index, which uses only air temperature and humidity.</p>
<p><iframe id="llrYv" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/llrYv/3/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Anyone can check their area’s projected wet bulb globe temperature using a <a href="https://digital.mdl.nws.noaa.gov/?zoom=4&lat=37&lon=-96.5&layers=F000BTTTFTT&region=0&element=8&mxmz=false&barbs=false&subl=TFFFFF&units=english&wunits=nautical&coords=latlon&tunits=localt">National Weather Service</a> website.</p>
<h2>How can you tell when someone is suffering from heat illness?</h2>
<p>There are several conditions that fall within the realm of “heat illnesses,” but these are the primary ones:</p>
<ul>
<li><p>Heat cramps, also referred to as exercise-associated muscle cramps, are caused either by dehydration and electrolyte losses or tired muscle groups. They’re easy to spot when a muscle group tightens and knots. Heat cramps can typically <a href="https://ksi.uconn.edu/emergency-conditions/heat-illnesses/heat-cramps/">be treated with</a> rest, stretching and hydration with electrolytes. If someone is complaining of cramps but the muscles are not knotted and tight to the touch, then that person could be experiencing <a href="https://ksi.uconn.edu/emergency-conditions/exertional-sickling/">an emergency condition</a> related to sickle cell trait called exertional sickling.</p></li>
<li><p><a href="https://ksi.uconn.edu/emergency-conditions/heat-illnesses/heat-exhaustion/">Heat exhaustion</a> can occur when a person is dehydrated and exercising in warm conditions. Eventually, the body is unable send enough blood to both the working muscles and the skin for heat dissipation. It will prioritize the heat dissipation, and the person either collapses or can’t continue exercising. This should be treated by placing the person in shade or air conditioning, giving them something to drink, and cooling them with fans or cold towels. If they don’t respond quickly, they may need medical attention.</p></li>
<li><p><a href="https://www.cdc.gov/niosh/topics/heatstress/heatrelillness.html">Exertional heat stroke</a> is a medical emergency in which a person’s body temperature is over 105 F (40.6 C). Unfortunately, traditional temperature devices like oral and forehead thermometers don’t measure body temperature accurately in these situations. If a person has been exercising in warm conditions and their personality changes, they start acting weird or different or become confused, you should suspect exertional heat stroke. First responders should place the heat stroke victim in a cold water immersion tub up to their shoulders and make the water as cold as possible with ice. If that’s not available, any kind of water immersion like a baby pool, creek, tarp filled with water, or dousing should be used. EMS should be called immediately. </p></li>
</ul>
<p>An important clue in all of these heat illnesses is that the person is almost always sweating. It is a myth that the person will stop sweating; this rarely happens.</p>
<h2>What do athletic trainers recommend for keeping athletes safe in the heat, particularly in those first weeks?</h2>
<p>Teams should follow <a href="https://doi.org/10.4085/1062-6050-596-20">heat acclimatization guidance</a> to gradually increase the length of training sessions and the intensity of workouts. For example, an expert group that reviewed research on youth sports <a href="https://doi.org/10.4085/1062-6050-596-20">recommended always keeping training or practice sessions under two hours</a> and only once a day in the first week. Conditioning, such as repetitive running and timed drills, should be held in an air-conditioned area or not integrated for the first two weeks. </p>
<p>In addition, teams should pay attention to <a href="https://ksi.uconn.edu/prevention/wet-bulb-globe-temperature-monitoring/">wet bulb globe temperature</a> tables for their part of the country and avoid exercising in the hottest part of the day, generally 10 a.m. to 6 p.m.</p>
<p>The <a href="https://doi.org/10.4085/1062-6050-50.9.07">National Athletic Trainers Association also recommends</a>: using “<a href="https://doi.org/10.4085/1062-6050-0373.19">weight charts</a>” to help players understand how much they need to drink to stay hydrated; having on-site athletic trainers with treatment resources, such as cold-water tubs; encouraging good sleep and nutrition; and providing a safe work-to-rest ratio during conditioning and practice sessions. Breaks should be in the shade, ideally with cooling devices such as fans, misters and cold towels. If a hard or intense drill is completed, players should have an equally long break.</p>
<p>A buddy system is also beneficial. With a buddy, someone is more likely to notice when an athlete isn’t feeling well or is starting to act out of character and needs to be stopped for evaluation.</p><img src="https://counter.theconversation.com/content/187655/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Susan Yeargin is affiliated with Korey Stringer Institute Medical and Science Advisory Board and the NATA Foundation Research and Pronouncements Committees. </span></em></p>The first two weeks of preseason training are the toughest as players’ bodies acclimatize to running hard in the heat. An exercise scientist explains the risks.Susan Yeargin, Associate Professor of Athletic Training, University of South CarolinaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1833542022-05-24T03:10:02Z2022-05-24T03:10:02ZWhy do my armpits smell? And would using glycolic acid on them really work?<figure><img src="https://images.theconversation.com/files/464442/original/file-20220520-25-f6x9om.jpg?ixlib=rb-1.1.0&rect=0%2C8%2C5760%2C3819&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>You showered this morning, are wearing fresh clothes and having an otherwise normal day, when suddenly you notice <em>that</em> stench. </p>
<p>Why do our armpits smell, and why more at some times than others? </p>
<p>It all comes down to an oily secretion from special glands beneath our skin, which are very prevalent under the armpits, and more active at certain times.</p>
<p>And despite what you might have heard on Instagram or TikTok, wiping under your arms with glycolic acid is not the best long-term solution.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-why-do-i-sweat-so-much-and-how-can-i-stop-it-22060">Explainer: why do I sweat so much and how can I stop it?</a>
</strong>
</em>
</p>
<hr>
<h2>The oily paste</h2>
<p>The main sweat glands (called “eccrine” sweat glands) covering most of our body secrete primarily water, which is odourless and evaporates to cool us down.</p>
<p>However, our body is also equipped with a second type of sweat gland, called “apocrine sweat glands”.</p>
<p>They’re mostly around areas with lots of hair follicles, such as the armpits and groin. These glands secrete an oily compound, and become more active in response to stress, fear, anxiety, pain, and sexual stimulation. </p>
<p>Initially odourless, this oily secretion provides great food for bacteria living on our skin.</p>
<p>The bacteria convert this sweat into <a href="https://asm.org/Articles/2021/December/Microbial-Origins-of-Body-Odor">fatty acids</a>, and compounds that produce scents, giving off an odour with smell traces reminiscent of onion, cumin, and rotten meat. </p>
<p>The type of bacteria is relatively consistent between people, but the balance between each type can be different.</p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0022202X1534687X">Genetics</a> play a prominent role in how we smell.</p>
<p>And because our apocrine glands respond to emotions, our thoughts and lifestyle can influence on their activity.</p>
<p>Even some foods, such a lot of <a href="https://academic.oup.com/chemse/article/31/8/747/364338">red meat</a>, can alter the smell.</p>
<p>For both men and women, underarm hair can also cause a more prominent <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4793925/">smell</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/464438/original/file-20220520-18-bg50yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/464438/original/file-20220520-18-bg50yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464438/original/file-20220520-18-bg50yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464438/original/file-20220520-18-bg50yc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464438/original/file-20220520-18-bg50yc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464438/original/file-20220520-18-bg50yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464438/original/file-20220520-18-bg50yc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464438/original/file-20220520-18-bg50yc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Our apocrine glands respond to emotions.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-do-our-toes-and-fingers-get-wrinkly-in-the-bath-120229">Curious Kids: why do our toes and fingers get wrinkly in the bath?</a>
</strong>
</em>
</p>
<hr>
<h2>But what’s the role of this smell?</h2>
<p>Apocrine sweat glands don’t generally activate until puberty, which is why body odour isn’t really a concern when we’re young.</p>
<p>The scent also changes with the production of hormones.</p>
<p>For example, during the menstrual cycle, the most “attractive” smell occurs around the time of <a href="https://academic.oup.com/beheco/article/15/4/579/205993">ovulation</a>, when women are <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1439-0310.2006.01125.x">most fertile</a>. However, the sexual function of body odour doesn’t appear to play a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6773238/">major role</a> in humans.</p>
<p>Nonetheless, there may be some social relevance to our unique scent. Newborn babies can recognise their mother’s armpit smells a few weeks <a href="https://pubmed.ncbi.nlm.nih.gov/4075877/">after delivery</a>, and mothers can distinguish the smell of their own baby by about <a href="https://academic.oup.com/chemse/article/31/8/747/364338">three weeks</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-causes-dry-lips-and-how-can-you-treat-them-does-lip-balm-actually-help-161264">What causes dry lips, and how can you treat them? Does lip balm actually help?</a>
</strong>
</em>
</p>
<hr>
<h2>How to avoid the odour?</h2>
<p>Our sweat gland secretions are odourless, so the longer the bacteria on our skin have to process the oils, the more scented compounds they can produce. </p>
<p>That’s why showering every day helps reduce odour.</p>
<p>Antiperspirants reduce the amount of sweat released by the glands. This is usually due to ingredients such as aluminium, which form a temporary blockage in the glands.</p>
<p>Deodorants work to mask the odours with stronger, pleasant scents. They often also contain alcohols or ingredients that can turn your skin slightly acidic, or make the area less hospitable to bacteria.</p>
<p>Choose clothing wisely. If your skin is moist for a long time it gives bacteria a chance to grow. Clean clothes that allow for good airflow can help keep you smelling fresher for longer during the <a href="https://www.health.qld.gov.au/news-events/news/whats-the-go-with-body-odour">day</a>. </p>
<p>Caffeine, some medications, as well as some illicit drugs such as methamphetamine, MDMA, heroin and cocaine can increase sweating, which will affect body odour.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/463858/original/file-20220518-16-50xwdr.jpg?ixlib=rb-1.1.0&rect=0%2C37%2C4991%2C3659&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/463858/original/file-20220518-16-50xwdr.jpg?ixlib=rb-1.1.0&rect=0%2C37%2C4991%2C3659&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/463858/original/file-20220518-16-50xwdr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=445&fit=crop&dpr=1 600w, https://images.theconversation.com/files/463858/original/file-20220518-16-50xwdr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=445&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/463858/original/file-20220518-16-50xwdr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=445&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/463858/original/file-20220518-16-50xwdr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=559&fit=crop&dpr=1 754w, https://images.theconversation.com/files/463858/original/file-20220518-16-50xwdr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=559&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/463858/original/file-20220518-16-50xwdr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=559&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Our sweat gland secretions are odourless, so the longer the bacteria on our skin has to process the oils, the more scented compounds it can produce.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-do-we-have-eyebrows-157047">Curious Kids: why do we have eyebrows?</a>
</strong>
</em>
</p>
<hr>
<h2>What about antiperspirants and glycolic acid?</h2>
<p>You may have heard antiperspirants containing aluminium could cause cancer. The Cancer Council has <a href="https://www.cancer.org.au/iheard/can-deodorants-and-antiperspirants-with-aluminium-cause-cancer">called</a> this a myth and a rumour, with <a href="https://www.cancer.gov/about-cancer/causes-prevention/risk/myths/antiperspirants-fact-sheet">no scientific studies</a> specifically linking the use of these products to <a href="https://www.cancer.org.au/iheard/can-deodorants-and-antiperspirants-with-aluminium-cause-cancer">cancer</a>.</p>
<p>Nonetheless, it is wise to consider the cosmetics or chemicals we put on our skin. If you find your antiperspirant or deodorant is causing irritation or rashes, try a product with different ingredients or consult a doctor.</p>
<p>A recent <a href="https://www.refinery29.com/en-au/tiktok-the-ordinary-glycolic-acid-natural-deodorant">trend</a> on Tik Tok and Instagram suggests using glycolic acid (often used as an exfoliant for the face) on the armpits to reduce smell.</p>
<p>Theoretically, adding this chemical to your armpit will alter the environment under the arms. This can inhibit bacteria growth, and assist to reduce body odour. However, it could irritate the skin, particularly under the arms where there is a lot of friction, and especially if the area was recently shaved.</p>
<p>It will also not inhibit the amount you sweat.</p>
<p>Glycolic acid straight from the bottle will not act for long, as sweat from the armpits will dilute and neutralise its activity. This means even if it works temporarily, you’ll likely be back to your odorous ways pretty soon.</p>
<p>If you’re aiming to avoid chemical products, the best steps to an odour-free life are the obvious ones. Shower daily with soap (and dry off thoroughly), wear breathable fabrics (like cotton, linen or moisture-wicking sportswear), keep your clothes clean, reduce stress and limit your caffeine intake.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-know-hand-dryers-can-circulate-germs-through-the-air-why-are-they-still-used-everywhere-157410">We know hand dryers can circulate germs through the air. Why are they still used everywhere?</a>
</strong>
</em>
</p>
<hr>
<p><em>Thank you to PhD Candidate Charlotte Phelps for her assistance with this article.</em></p><img src="https://counter.theconversation.com/content/183354/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christian Moro does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>It all comes down to an oily secretion from special glands beneath our skin, which are very prevalent under the armpits, and more active at certain times.Christian Moro, Associate Professor of Science & Medicine, Bond UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1774542022-04-22T01:35:23Z2022-04-22T01:35:23ZWhat is toe jam? From harmless gunk to a feast for bugs<figure><img src="https://images.theconversation.com/files/456809/original/file-20220407-14-flir0u.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1000%2C664&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-girls-toes-healthy-beautiful-wellgroomed-1371423317">Shutterstock</a></span></figcaption></figure><p><a href="https://www.healthline.com/health/all-about-toe-jam">Toe jam</a> can be a source of fascination, disgust or barely noticed. It can be a sign you need to wash your feet or rethink your choice of footwear. It can also lead to major health issues.</p>
<p>Toe jam, the gunk and debris between your toes, has even made it to a Beatles song.</p>
<p>But it was unlikely John Lennon was thinking about foot hygiene when he wrote the lyrics to the second verse of <a href="https://genius.com/The-beatles-come-together-lyrics">Come Together</a>:</p>
<blockquote>
<p>He wear no shoeshine, he got toe-jam football</p>
<p>He got monkey finger, he shoot Coca-Cola</p>
<p>He say, ‘I know you, you know me’</p>
<p>One thing I can tell you is you got to be free.</p>
</blockquote>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/uSM5MpKSnqE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Yes, The Beatles really mentioned toe jam in Come Together (YouTube).</span></figcaption>
</figure>
<h2>What is toe jam, actually?</h2>
<p>Toe jam isn’t a medical term. There is no formal medical term to describe the dead skin cells, sweat, sock lint and dirt that combine in the small and often cramped spaces between our toes.</p>
<p>Toe jam can have the consistency of soft cheese or cake crumbs. It can smell or be odourless. And its colour can range from white to grey-brown.</p>
<p>You’re more likely to create toe jam if you wear closed-in shoes when it’s hot, or gumboots that don’t allow sweat to evaporate.</p>
<p>Poor foot hygiene will certainly make it more likely you’ll develop toe jam. That’s because sweaty debris accumulates in between the toes if you don’t pay attention to cleaning these areas in the shower or bath.</p>
<p>Toe jam may also be more likely if your feet sweat a lot for other reasons. For instance, we know <a href="https://www.racgp.org.au/afp/2009/september/sweaty-smelly-hands-and-feet">sweaty feet</a> can be a problem for children and adolescents, who have more active sweat glands. And some people have a serious medical condition called <a href="https://www.sweathelp.org/index.php">hyperhidrosis</a>, where they sweat excessively.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/anhidrosis-why-some-people-apparently-like-prince-andrew-just-cant-sweat-127280">Anhidrosis: why some people – apparently like Prince Andrew – just can't sweat</a>
</strong>
</em>
</p>
<hr>
<h2>Is toe jam like athlete’s foot?</h2>
<p>The collection of sweat and dead skin between toes provides bacteria living naturally on our skin the chance to thrive. </p>
<p>These bacteria, which include ones in the genus <em>Brevibacterium</em>, feed on sweat, releasing molecules that give the characteristic “cheesy” <a href="https://theconversation.com/why-do-feet-stink-by-the-end-of-the-day-125037">smell of sweaty feet</a>. Brevibacterium is also used to ripen some cheeses.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/457034/original/file-20220408-19484-ox4ymj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Soft cheese, cut in slices" src="https://images.theconversation.com/files/457034/original/file-20220408-19484-ox4ymj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/457034/original/file-20220408-19484-ox4ymj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=436&fit=crop&dpr=1 600w, https://images.theconversation.com/files/457034/original/file-20220408-19484-ox4ymj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=436&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/457034/original/file-20220408-19484-ox4ymj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=436&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/457034/original/file-20220408-19484-ox4ymj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=547&fit=crop&dpr=1 754w, https://images.theconversation.com/files/457034/original/file-20220408-19484-ox4ymj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=547&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/457034/original/file-20220408-19484-ox4ymj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=547&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">No wonder your feet smell cheesy if you don’t wash them properly.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cheeseboard-sliced-yellow-limburger-cheese-top-1343151806">Shutterstock</a></span>
</figcaption>
</figure>
<p>This warm and damp environment is also a perfect site for <a href="https://www.healthdirect.gov.au/tinea">tinea pedis</a>, a fungal skin infection you might know as athlete’s foot. </p>
<p>Signs of tinea might be soggy white skin between your toes, which can be itchy, and red areas, a sign of skin damage. <a href="https://dermnetnz.org/topics/athletes-foot">Damaged skin</a> between toes might develop small fluid-filled blisters and may also bleed if the weak skin is torn.</p>
<p>So while toe jam isn’t the same as tinea, it might provide the perfect conditions for the fungus to grow.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-do-feet-stink-by-the-end-of-the-day-125037">Why do feet stink by the end of the day?</a>
</strong>
</em>
</p>
<hr>
<h2>How serious is toe jam?</h2>
<p>Generally, toe jam is a minor health problem. You can <a href="https://www.racgp.org.au/getattachment/233c1fdf-8802-471e-9828-f792110c30d1/Sweaty-smelly-hands-and-feet.aspx">manage it</a> with good foot hygiene. And if you develop tinea, you can use a short course of an anti-fungal treatment you can buy from a pharmacy (see below).</p>
<p>It is quite a different prospect, however, for a person living with a chronic disease such as diabetes, someone who has poor vision (so can’t see toe jam or its complications developing), or who may be unable to reach their feet due to limited mobility.</p>
<p>Diabetes not well controlled with diet and exercise, or drugs, increases the <a href="https://www.diabetesfeetaustralia.org/">risk</a> of a person having reduced blood flow (peripheral arterial disease) and reduced feeling in their feet (sensory neuropathy). </p>
<p>Broken skin between the toes caused by tinea can become infected rapidly, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3248359/">increasing the risk</a> of:</p>
<ul>
<li><p>infection spreading to the foot and leg (cellulitis)</p></li>
<li><p>infection of the bone (osteomyelitis)</p></li>
<li><p>gangrene (dead tissue caused by lack of blood flow)</p></li>
<li><p>amputation of a toe, part of the foot or leg. </p></li>
</ul>
<p>So early identification of tinea in a vulnerable person is especially important to prevent complications.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/life-on-us-a-close-up-look-at-the-bugs-that-call-us-home-25754">Life on Us: a close-up look at the bugs that call us home</a>
</strong>
</em>
</p>
<hr>
<h2>4 ways to avoid problems</h2>
<p>Here are our four tips to avoid problems with toe jam, including developing tinea and its complications:</p>
<ol>
<li><p>wash the spaces between your toes and dry them carefully after a shower or bath, and after swimming. Gyms and swimming pools are a common place to pick up a fungal infection on your feet so it’s a good idea to wear thongs to reduce the risk of tinea</p></li>
<li><p>if possible, avoid wearing footwear that doesn’t allow sweat to evaporate (such as closed-in shoes made of synthetic material and gumboots). Going barefoot, when there is no risk of injury, will also allow sweat to evaporate</p></li>
<li><p>treat sweaty feet by using an <a href="https://www.racgp.org.au/afp/2009/september/sweaty-smelly-hands-and-feet">anti-perspirant</a> containing aluminium chloride. More severe cases of hyperhidrosis may be managed using drugs, such as <a href="https://www.dermcoll.edu.au/atoz/plantar-hyperhidrosis/">Botox</a> injections to the feet. Fungal infections (<a href="https://dermnetnz.org/topics/tinea-pedis">tinea</a>) should be treated using over-the-counter antifungal creams such a terbinafine or clotrimazole. Resistant infections might require a course of prescribed antifungal medicines</p></li>
<li><p>pay attention to <a href="https://www.healthline.com/health/all-about-toe-jam#when-to-see-a-doctor">signs</a> indicating an infection is spreading from the foot. These could be pain and swelling in the toes, or red streaks along the foot and up the leg. This requires an urgent visit to a podiatrist or doctor.</p></li>
</ol>
<h2>Footnote</h2>
<p>Lennon mentions a “walrus gumboot” in verse three of Come Together. The final line of verse two says “you got to be free”. The cover of The Beatles album Abbey Road shows Paul McCartney walking barefoot (second from the left).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/457039/original/file-20220408-18-vvxes4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Beatles album Abbey Road propped up behind turntable playing a record" src="https://images.theconversation.com/files/457039/original/file-20220408-18-vvxes4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/457039/original/file-20220408-18-vvxes4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/457039/original/file-20220408-18-vvxes4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/457039/original/file-20220408-18-vvxes4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/457039/original/file-20220408-18-vvxes4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/457039/original/file-20220408-18-vvxes4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/457039/original/file-20220408-18-vvxes4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Maybe The Beatles were onto something.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/naples-italy-10032019-fabulous-beatles-depicted-1334880947">Imma Gambardella/Shutterstock</a></span>
</figcaption>
</figure>
<p>Maybe the Beatles did know a thing or two about toe jam and foot health.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/beatles-abbey-road-at-50-is-a-marker-of-how-pop-music-grew-up-in-the-1960s-124433">Beatles: Abbey Road at 50 is a marker of how pop music grew up in the 1960s</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/177454/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Caroline Robinson is affiliated with the Australasian Council of Podiatry Deans and the Australian Podiatry Association.</span></em></p><p class="fine-print"><em><span>Luke Donnan is affiliated with the Australasian Council of Podiatry Deans and the Australian Podiatry Association.</span></em></p>Toe jam was mentioned in a song by The Beatles. Maybe they knew a thing or two about foot hygiene.Caroline Robinson, Associate Professor Podiatry, Charles Sturt UniversityLuke Donnan, Lecturer in Podiatry, Charles Sturt UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1763652022-02-16T01:09:01Z2022-02-16T01:09:01ZHow humid is it? 3 things to keep you cool in a hot and sticky summer (and 3 things that won’t)<figure><img src="https://images.theconversation.com/files/445592/original/file-20220210-24693-kz2jtl.jpg?ixlib=rb-1.1.0&rect=1%2C0%2C997%2C663&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/portrait-woman-front-fan-suffering-heat-1745759825">Shutterstock</a></span></figcaption></figure><p><a href="http://www.bom.gov.au/climate/updates/articles/a020.shtml">La Niña</a> has resulted in <a href="https://www.smh.com.au/environment/weather/sydney-smashes-january-humidity-records-as-la-nina-nears-its-peak-20220118-p59p3m.html">a humid summer</a> for much of eastern Australia.</p>
<p>This climate pattern typically causes warm, humid air to rise from the western Pacific Ocean, ultimately leading to greater cloud formation, increased rainfall, and higher humidity along Australia’s eastern seaboard and tropical north.</p>
<p>So what’s the best way to cope with what’s left of a hot and humid La Niña summer?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/back-so-soon-la-nina-heres-why-were-copping-two-soggy-summers-in-a-row-173684">Back so soon, La Niña? Here's why we're copping two soggy summers in a row</a>
</strong>
</em>
</p>
<hr>
<h2>In praise of sweat (and evaporation)</h2>
<p>Sweating (and the heat loss that goes with it) is by far the most effective way our bodies use to cool us down. But it’s not sweating <em>alone</em> that does the trick. It’s the evaporation of sweat that is key.</p>
<p>For every gram of sweat you evaporate, a little over <a href="https://journals.physiology.org/doi/abs/10.1152/jappl.1972.32.4.456">2.4 kilojoules</a> of heat energy is taken with it.</p>
<p>That’s a bit difficult to visualise. So let’s think of it in terms of boiling water.</p>
<p>Evaporating roughly 140 grams of sweat results in enough energy (heat) “loss” to bring a litre of 20°C water to boiling point (at sea level).</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1487831263931088897"}"></div></p>
<p>We were treated to some interesting facts during this year’s notoriously sweaty Australian Open tennis tournament.</p>
<p>Champion player Rafael Nadal was reported to have evaporated <a href="https://www.theguardian.com/sport/2022/jan/28/tug-tuck-wipe-repeat-nadals-rituals-help-defy-his-breaking-body">over 4 kilograms of sweat</a> during his <a href="https://ausopen.com/match/2022-denis-shapovalov-vs-rafael-nadal-ms502">4 hour 8 minute quarter-final win</a> over Denis Shapovalov.</p>
<p>That’s the equivalent of brewing a 250 millilitre cup of tea via the energy of his own sweat-liberated-heat – every 2.2 minutes of the match.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-how-to-exercise-safely-in-the-heat-37286">Health Check: how to exercise safely in the heat</a>
</strong>
</em>
</p>
<hr>
<h2>So how is this all related to humidity?</h2>
<p>Sweat evaporation is dictated primarily by the wetness of the skin, and the absolute humidity of the air. <a href="https://www.weather.gov/lmk/humidity">Absolute humidity</a> is a function of the amount of water vapour in the air. </p>
<p>This is not to be confused with <a href="http://www.bom.gov.au/watl/humidity/">relative humidity</a> which is the term usually used in weather reports. This tells us how much water vapour the air is holding (as a percentage) relative to how much it could possibly hold, which goes up with temperature.</p>
<p>The bigger the difference between the wetness of the skin and the absolute humidity, the more readily sweat evaporates.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-do-i-sweat-so-much-131135">Why do I sweat so much?</a>
</strong>
</em>
</p>
<hr>
<p>In arid climates, such as central Australia, where the absolute humidity is low, sweat evaporates so rapidly you can barely feel it on your skin.</p>
<p>Whereas in humid conditions, such as in northern Australia and more recently much of eastern Australia, sweat evaporation is hindered. </p>
<p>This is why on humid days we think we’re much sweatier, when in reality we may not be sweating that much more than any other warm day. It’s just more sweat is staying on our skin (rather than evaporating), forming patches on our clothes and making us feel sticky.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/445856/original/file-20220211-238-8kkvvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Man sweating in blue shirt" src="https://images.theconversation.com/files/445856/original/file-20220211-238-8kkvvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/445856/original/file-20220211-238-8kkvvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/445856/original/file-20220211-238-8kkvvj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/445856/original/file-20220211-238-8kkvvj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/445856/original/file-20220211-238-8kkvvj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/445856/original/file-20220211-238-8kkvvj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/445856/original/file-20220211-238-8kkvvj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hot and sticky with all this humidity?</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/man-hyperhidrosis-sweating-very-badly-under-767078800">Shutterstock</a></span>
</figcaption>
</figure>
<h2>What can we do about it?</h2>
<p>These three simple strategies will actually keep you cool on a humid day (without aircon):</p>
<p><strong>1. Use a fan</strong></p>
<p>Use a fan to <a href="https://jamanetwork.com/journals/jama/article-abstract/2110959">increase air flow</a> and accelerate sweat evaporation. These tend to work <a href="https://www.sciencedirect.com/science/article/pii/S2542519621001364">to at least 39°C</a>.</p>
<p>Misting fans <a href="https://www.sciencedirect.com/science/article/pii/S1440244021001092?casa_token=VfKIET08fTEAAAAA:2n8OqjI1xPzZB-ASMkeyIhrZplzkjItRSooTTT1OdrewatuuDbDiDzwYDiRCBYO5anHUyvBnKg">also work</a> well as water settles on the skin and subsequently evaporates, taking body heat with it. Alternatively, you can spray your skin with water and <a href="https://www.sciencedirect.com/science/article/pii/S0048969720347094">sit in front of a fan</a>.</p>
<p><strong>2. Use ‘ice towels’</strong></p>
<p>Wrap <a href="https://journals.lww.com/acsm-msse/fulltext/2017/05000/In_Play_Cooling_Interventions_for_Simulated.16.aspx">crushed ice in a damp towel</a> and wrap it around your neck. Professional tennis players regularly do this to keep cool. This circumvents the need for evaporation by taking heat straight from the body via conduction.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1476878329516937218"}"></div></p>
<p><strong>3. Wet your clothes</strong> </p>
<p>Soaking your t-shirt with water and putting it back on <a href="https://journals.physiology.org/doi/full/10.1152/japplphysiol.00786.2019">reduces the increase in core temperature</a> the same way as the evaporation of sweat. But it has the added bonus of not dehydrating the body. Alternatively, directly wetting the skin with a spray or wet sponge provides <a href="https://jamanetwork.com/journals/jama/article-abstract/2752456">the same benefit</a>.</p>
<h2>What won’t work</h2>
<p>Here are three strategies commonly recommended for beating the heat that won’t always work.</p>
<p><strong>1. Evaporative cooling</strong></p>
<p><a href="https://www.choice.com.au/home-and-living/cooling/air-conditioners/articles/evaporative-cooler-vs-air-conditioner">Evaporative coolers</a> work by passing hot air across a wet membrane to cool it. These work really well on hot, dry days. But on humid days, the air can hold less extra water, so evaporation is reduced and therefore, air is cooled far less.</p>
<p><strong>2. Drinking chilled drinks</strong></p>
<p>Although cold drinks may feel like they cool you down, it is mainly in your mind. Your body warms up the cold fluids or ice. At the same time, this triggers a <a href="https://journals.physiology.org/doi/full/10.1152/japplphysiol.01059.2013">reduction in sweating</a>, which reduces the amount of heat you lose via evaporation. One cancels out the other.</p>
<p>This results in the <a href="https://link.springer.com/article/10.1007/s40279-017-0842-8?platform=hootsuite_1&error=cookies_not_supported&code=890690fa-dc5b-493a-8ad7-9ccef673e811">same body temperature</a> irrespective of how cold (or hot) the drink is.</p>
<p>We’re not suggesting abandoning drinks altogether. In fact, you do need to replenish water that you sweat, to avoid dehydration. But don’t expect cold drinks to perform any better than warm ones. Just drink fluid at the temperature you find most palatable.</p>
<p>Similarly, eating cold food, such as ice cream or other frozen or chilled snacks, does not result in any net cooling effect. By all means, eat them if they make you feel better, but don’t expect them to actually cool you down.</p>
<p><strong>3. Sunscreen</strong></p>
<p>While it is very important to protect you skin from UV, there is no evidence wearing sunscreen makes any difference to how hot you get or how hot you feel.</p><img src="https://counter.theconversation.com/content/176365/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ollie Jay receives funding from National Health and Medical Research Council (NHMRC), Wellcome Trust (UK), MS Research Australia, NSW Dept of Industry and Environment, Tennis Australia, Cricket Australia, National Rugby League (NRL). He also serves as a consultant on research projects for the National Institutes of Health and US Dept of Defence. He served on Board of Trustees for the American College of Sports Medicine (ACSM) from 2018-21</span></em></p><p class="fine-print"><em><span>Connor Graham does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>On a hot and humid day, the fan is your friend. But ice cream won’t make the difference you think it will.Connor Graham, Research Fellow, Thermal Ergonomics Laboratory, University of SydneyOllie Jay, Professor of Heat & Health; Director of Heat & Health Research Incubator; Director of Thermal Ergonomics Laboratory, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1747702022-01-31T15:49:59Z2022-01-31T15:49:59ZHow sweat sensors could play a critical role in monitoring our health<figure><img src="https://images.theconversation.com/files/443001/original/file-20220127-22-9eyjrs.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6000%2C3988&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sweat contains information on the condition of our bodies.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Sweat is a biological fluid — like blood, saliva and urine — that contains metabolites, electrolytes, proteins and hormones. The levels of these vary depending on a person’s health. Wearable sweat sensors have been developed to <a href="https://doi.org/10.1007/s42242-021-00171-2">track users’ health condition and monitor the levels of these substances (known as analytes) in sweat</a>. </p>
<p>Lactate is considered an important biomarker thanks to its involvement in anaerobic metabolism. The undesired accumulation of lactate in muscles can result in fatigue, so changes in the concentration of lactate in sweat can be used to monitor fatigue. At Simon Fraser University’s Additive Manufacturing Laboratory, we have developed <a href="https://doi.org/10.1038/srep30565">a flexible sensor for sweat lactate</a>. </p>
<p>The benefit of using wearable sweat sensors is the capability for real-time, non-invasive and continuous monitoring of sweat. However, there are still challenges that must be overcome for practical biomedical applications such as diagnosis of health conditions.</p>
<h2>Sweat challenges</h2>
<p>One of the first hurdles in developing a reliable sweat sensor is the difficulty of collecting and routing of sweat. There are various methods for sampling sweat for sensing. One of the most representative approaches for collecting sweat is using <a href="https://doi.org/10.1021/acssensors.0c02446">microfluidic systems with channels that deliver sweat</a>. </p>
<p>Absorbent materials like cloth can also be <a href="https://doi.org/10.1007/s10570-019-02396-y">used for sweat sampling for sensing</a>. However, sampling sweat takes time, and how to handle the sweat sample and supply it in the sensing region in a continuous and stable manner remains a challenge for real-time measurement through continuous sensing of freshly generated sweat. </p>
<p>One of the most recent demonstrations used an <a href="https://doi.org/10.1038/s41467-020-18238-6">integrated microfluidic system with thermo-responsive hydrogels</a>. This system demonstrated significant potential for programmable control of sweat routing and sensing, which will improve the sweat handling for future sweat sensors.</p>
<p>Secondly, there is no single representative analyte in sweat. <a href="https://doi.org/10.1039/c9lc00103d">Sweat sensors can detect analytes</a> such as <a href="https://doi.org/10.1039/c9lc01045a">ammonia, ethanol</a>, ions, glucose, lactate, sweat chloride, pH, urea and creatinine, but there isn’t a single analyte that can independently provide a significant picture of an individual’s health. This means that sweat sensors must be able to measure many different substances in sweat to provide a useful report.</p>
<p>There are several sweat sensor products coming to market <a href="https://newsroom.ucla.edu/releases/adhesive-turns-smartwatch-into-biomedical-system">that measure analytes like the protein cytokine</a> and <a href="https://www.epicorebiosystems.com/">glucose and lactate</a>. </p>
<p>A third challenge is the reliability and accuracy of sweat sensors. If we measure the level of a target analyte from sweat, can we determine how reliable the result is in terms of judging the level of the same analyte in subject’s blood?</p>
<p>We still need to determine the relationship between <a href="https://doi.org/10.1039/c8lc01082j">levels of analyte in sweat and blood</a>, and <a href="https://doi.org/10.1126/sciadv.aaw9906">the relationship between sweats from different parts of body</a>. This recent study demonstrated that sweat bio-sensing can provide blood-correlated ethanol concentration data, which gives us hope that it may be possible to find blood-correlated concentrations for other analytes as well.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A woman wearing a red t-shirt checks her blood glucose level" src="https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=409&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=409&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=409&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=514&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=514&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=514&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">People living with diseases like diabetes can benefit from non-invasive and real-time monitoring.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Powerful solutions</h2>
<p>Users can specifically monitor targeted analytes in real-time by non-invasive sweat sensing. This can save time, energy and resources by helping people avoid painful and inconvenient invasive tests, improving health and living standards, and receiving medical assistance in a timely manner. </p>
<p>Wearable sweat sensors are a powerful solution for monitoring daily health, and could support the prevention, diagnosis, treatment and prognosis of diseases. Technological applications may come earlier than we expected through close collaboration between clinical doctors, scientists and engineers.</p><img src="https://counter.theconversation.com/content/174770/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr. Woo Soo Kim at Simon Fraser University received funding from Natural Sciences and Engineering Research Council of Canada (NSERC). </span></em></p><p class="fine-print"><em><span>Taeil Kim does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Sensors that measure sweat could be coming to the market soon, but for them to be useful, we’ll need to understand more about this fluid that our body produces.Woo Soo Kim, Associate Professor, Mechatronic Systems Engineering, Simon Fraser UniversityTaeil Kim, Postdoctoral fellow, Applied Sciences, Simon Fraser UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1699412021-11-24T03:31:44Z2021-11-24T03:31:44ZHow to wear a mask in the heat<figure><img src="https://images.theconversation.com/files/433580/original/file-20211123-20-1cxhigv.jpg?ixlib=rb-1.1.0&rect=2%2C1%2C995%2C664&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/family-attractive-pineapples-wearing-face-mask-1685952682">Shutterstock</a></span></figcaption></figure><p>Summer is on its way and you might be wondering how you’re going to wear a mask as the weather gets warmer.</p>
<p>Which mask is best? Is there anything you can do to prevent “<a href="https://www.dailycardinal.com/article/2021/02/how-to-handle-macne?ct=content_open&cv=cbox_latest">macne</a>”? How can you stop the ear loops from chafing? How do you prevent your sunglasses fogging up? </p>
<p>Here are some practical tips to keep you comfortable while helping you stay safe.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/which-mask-works-best-we-filmed-people-coughing-and-sneezing-to-find-out-143173">Which mask works best? We filmed people coughing and sneezing to find out</a>
</strong>
</em>
</p>
<hr>
<h2>Which mask is best in the heat?</h2>
<p><a href="https://www.bmj.com/content/372/bmj.n432">Disposable surgical masks</a> are more effective at filtering out viruses than cloth masks but to remain effective they should only be used once. Cloth masks are not quite as effective but can be washed and reused. </p>
<p>According to the World Health Organization, cloth masks <a href="https://www.bmj.com/content/372/bmj.n432">should have three layers</a>. The inner layer should be soft cotton as this is <a href="https://theconversation.com/how-do-i-know-if-my-mask-actually-works-what-about-the-candle-test-144124">more comfortable on the face</a>. This is also more absorbent, and less irritating, than synthetic materials. <a href="https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/types-of-masks.html">Cloth masks</a> with synthetic material in the inner layer will also increase sweating, so avoid these.</p>
<p>All masks become less effective when damp – from the damp air you exhale and from your sweat. The best mask to wear in the heat is the one you are most likely to wear.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/433595/original/file-20211124-21-10ufex3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Cloth masks laid out on a yellow background" src="https://images.theconversation.com/files/433595/original/file-20211124-21-10ufex3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/433595/original/file-20211124-21-10ufex3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/433595/original/file-20211124-21-10ufex3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/433595/original/file-20211124-21-10ufex3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/433595/original/file-20211124-21-10ufex3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/433595/original/file-20211124-21-10ufex3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/433595/original/file-20211124-21-10ufex3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">If you choose a cloth mask, make sure the inner layer is made from soft cotton.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/flat-lay-design-colorful-fashion-face-1683124312">Shutterstock</a></span>
</figcaption>
</figure>
<h2>Sweating, wearing masks and macne</h2>
<p>Wearing a mask can affect your skin in a number of ways. It <a href="https://pubmed.ncbi.nlm.nih.gov/32605056/">increases skin temperature</a> and sweating, which can worsen acne or other skin conditions. That’s where the term “macne” or “<a href="https://www.wired.com/story/mascne-causes-and-treatments/">mascne</a>” comes from.</p>
<p>Mask wearing also <a href="https://pubmed.ncbi.nlm.nih.gov/33217053/">increases production of sebum</a> (skin oil), which can clog pores. </p>
<p>Masks can cause friction if they don’t fit well. They can also cause sensitivity reactions if the innermost layer is made from synthetic fibres, and depending on how you wash them.</p>
<p>While it might seem odd, your skin also <a href="https://pubmed.ncbi.nlm.nih.gov/33813749/">gets drier</a> under a mask. That’s possibly because the humidity under the mask disrupts the normal skin barrier. </p>
<p><strong>What to do</strong></p>
<p>If you want to wear a cloth mask, a soft cotton-lined one is recommended to reduce the risk of skin irritation. <a href="https://www.aad.org/public/everyday-care/skin-care-secrets/face/prevent-face-mask-skin-problems">Dermatologists also recommend</a> avoiding makeup, such as some foundation and face powder, when wearing a mask, to avoid clogging the pores.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1300116312371408898"}"></div></p>
<p>Dermatologists <a href="https://www.aad.org/public/everyday-care/skin-care-secrets/face/prevent-face-mask-skin-problems">also recommend</a> washing your mask regularly, preferably after each use. If you are prone to skin conditions use a laundry detergent for sensitive skin to wash your mask, as normal laundry detergents contain perfumes and chemicals that can cause skin reactions. Avoid using fabric softeners for the same reason. </p>
<p>Dermatologists also <a href="https://www.aad.org/public/everyday-care/skin-care-basics/care/face-washing-101">suggest</a> washing your face morning and night with lukewarm water and a mild cleanser and avoiding irritating solutions such as retinoids or aftershave. A <a href="https://www.aad.org/public/everyday-care/skin-care-secrets/face/prevent-face-mask-skin-problems">moisturiser</a> before and after mask wearing can help rehydrate the skin; ensuring your mask fits snugly will reduce friction.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/13-insider-tips-on-how-to-wear-a-mask-without-your-glasses-fogging-up-getting-short-of-breath-or-your-ears-hurting-143001">13 insider tips on how to wear a mask without your glasses fogging up, getting short of breath or your ears hurting</a>
</strong>
</em>
</p>
<hr>
<h2>Avoid sore ears</h2>
<p>When you wear a mask for extended periods, the elastic loops can cause painful pressure on the backs of your ears.</p>
<p>To prevent this, use <a href="https://www.usatoday.com/videos/tech/problemsolved/2021/01/05/use-paper-clips-save-your-ears-face-mask-loop-pressure/4130220001/">paper clips</a> to join the loops together at the back of your head, taking the pressure off your ears.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1251910401219940352"}"></div></p>
<p>Another nifty solution is to use a <a href="https://www.businessinsider.com.au/headband-that-holds-up-face-mask-healthcare-workers-2020-4">headband with buttons</a> or paper clips attached. You attach the ear loops to the buttons/paper clips rather than putting the loops over your ears.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1247989374194720769"}"></div></p>
<h2>How do you stop your sunnies fogging up?</h2>
<p>People who wear prescription glasses will be used to avoiding fogging while wearing a mask. The same advice applies to people wearing sunglasses.</p>
<p>Sunnies fog up when you wear a mask because the warm water vapour in your breath comes out the top of your mask <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3293317/">and condenses</a> on your lenses.</p>
<p>Prevent the moist air from reaching your sunnies by:</p>
<ul>
<li><p>resting them on the mask rather than above the mask. The pressure of the sunnies reduces the chance of vapour exiting the top of the mask</p></li>
<li><p>pinching the top of the surgical mask to improve the fit around the top of your nose. If using a cloth mask, insert a pipe cleaner in the top to shape the mask over the nose</p></li>
<li><p>using soft tape suitable for skin to tape down the top of the mask. If you do this, test the tape somewhere else on your body first to make sure you don’t have a reaction to it.</p></li>
</ul>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1461730641125548033"}"></div></p>
<p>Other anti-fogging strategies include:</p>
<ul>
<li><p>using anti-fogging wipes or spray on the lenses, which you can buy over the counter from your local pharmacy or at an optometrist</p></li>
<li><p>making your own anti-fogging effect by rubbing a thin layer of liquid soap or shaving cream across the inside of each lens.</p></li>
</ul>
<p>Use anti-fogging solutions with care, though, as some may damage any anti-glare or anti-UV films on the lens. Check with your optometrist if unsure.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/cant-get-your-kid-to-wear-a-mask-here-are-5-things-you-can-try-166648">Can't get your kid to wear a mask? Here are 5 things you can try</a>
</strong>
</em>
</p>
<hr>
<h2>In a nutshell</h2>
<p>Whether you choose to wear a cloth or surgical mask this summer, these simple tips will help this become more comfortable as the temperatures rise, you sweat more and your skin may become more irritated.</p>
<p>But make sure you wear your mask correctly. Wearing it <a href="https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/types-of-masks.html">under your nose</a> makes it completely ineffective. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/its-easy-to-judge-but-some-people-really-cant-wear-a-mask-143258">It's easy to judge. But some people really can't wear a mask</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/169941/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Thea van de Mortel teaches into the Griffith University postgraduate Infection Prevention and Control program. </span></em></p>Here are some practical tips to keep you comfortable while helping you stay safe.Thea van de Mortel, Professor, Nursing and Deputy Head (Learning & Teaching), School of Nursing and Midwifery, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1646882021-07-21T12:26:07Z2021-07-21T12:26:07ZHeat stroke is a danger, but cardiovascular stress causes more heat wave deaths<figure><img src="https://images.theconversation.com/files/411997/original/file-20210719-15-rxda7x.JPG?ixlib=rb-1.1.0&rect=101%2C173%2C3676%2C2071&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A Salvation Army emergency vehicle is set up as a cooling station during a heatwave in Calgary, Alta. on June 30. </span> <span class="attribution"><span class="source">THE CANADIAN PRESS/Jeff McIntosh</span></span></figcaption></figure><p>Every summer we invariably deal with at least one heat wave. With global warming, they are becoming <a href="https://climateatlas.ca/map/canada/hwnum_2030_45#z=4&lat=48.84&lng=-90.26">longer, more intense and more frequent</a>. Heat waves are now among the most dangerous global natural hazards we face, accounting for more fatalities on average than any other extreme weather event, according to the <a href="https://www.weather.gov/hazstat/">United States National Weather Service</a>. </p>
<p>Canada is not immune, as evidenced by the recent heat wave across the Pacific Northwest that included a <a href="https://www.cbc.ca/news/canada/british-columbia/bc-alberta-heat-wave-heat-dome-temperature-records-1.6084203">Canadian record-breaking temperature of nearly 50 C</a> in Lytton, B.C. near the end of June. During the week of the heat wave, the province had <a href="https://www2.gov.bc.ca/assets/gov/birth-adoption-death-marriage-and-divorce/deaths/coroners-service/news/bccs-chief-coroner-updated-statement2.pdf">tripled the number of reported deaths</a> that normally occur during that period. </p>
<p>While the sharp rise in mortality rate during a heat wave is apparent, the cause of those deaths may not always be. Heat stroke is not the only issue. The biggest factor is the stress that extreme heat places on the cardiovascular system (the heart and blood vessels).</p>
<h2>Heat stroke</h2>
<p>Heat stroke, perhaps the most obvious consequence of a heat wave, is the progression of <a href="https://www.mayoclinic.org/diseases-conditions/heat-exhaustion/symptoms-causes/syc-20373250">heat exhaustion</a>, a milder condition that causes symptoms such as heavy sweating, clammy skin, fatigue, feeling faint or dizzy, nausea and headache. </p>
<p><a href="http://doi.org/10.1056/NEJMra1810762">Heat stroke</a> is serious and can be life-threatening. It is subclassified as either classic (occurring when someone is at rest) or exertional (occurring through strenuous physical activity). Both forms result in a series of reactions that cause excessive inflammation, leading to central nervous system dysfunction (confusion, seizures or loss of consciousness) and multiple organ failure.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/412000/original/file-20210719-19-a0839w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A man walking on a park path with the Calgary skyline in the distance, with a haze of smoke" src="https://images.theconversation.com/files/412000/original/file-20210719-19-a0839w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/412000/original/file-20210719-19-a0839w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/412000/original/file-20210719-19-a0839w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/412000/original/file-20210719-19-a0839w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/412000/original/file-20210719-19-a0839w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/412000/original/file-20210719-19-a0839w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/412000/original/file-20210719-19-a0839w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Following the western heat wave, a haze of wildfire smoke from British Columbia hangs over downtown Calgary in July 2021.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Jeff McIntosh</span></span>
</figcaption>
</figure>
<p>In classic heat stroke, it is poor heat-dissipating mechanisms or simply excessive heat exposure that is the culprit. With exertional heat stroke, it is the excessive metabolic heat during exercise that exceeds the body’s ability to maintain its temperature through heat-loss mechanisms like sweating. The common characteristic of both forms is a core temperature exceeding 40.5C (normal is 37C). </p>
<p>While heat stroke during a heat wave is certainly a risk, it alone provides a narrow scope of the true health impact. Most often, excess mortality during a heat wave is actually a result of increased cardiovascular burden and amplification of existing health conditions.</p>
<h2>Cardiovascular burden of heat</h2>
<p>When core and skin temperature rise, thermosensors across the body respond by shunting a large proportion of blood to the periphery (skin). This has two primary effects: </p>
<ol>
<li>It increases the skin blood flow allowing an increased sweat rate, and in turn, heat loss via evaporation.</li>
<li>It increases the skin temperature to enable more heat transfer from the body to the environment (heat loss primarily via convection).</li>
</ol>
<p>This process of increasing blood flow to the skin to regulate body temperature (thermoregulation) is taxing on the cardiovascular system. The blood vessels near the skin need to dilate, and the heart needs to pump harder and faster. </p>
<p>That is where the major problem lies: A large fraction of the population has some form of cardiovascular disease. Nearly 10 per cent of Canadian adults suffer from <a href="https://www.canada.ca/en/public-health/services/publications/diseases-conditions/report-heart-disease-Canada-2018.html">heart disease</a>, and nearly two-thirds of Canadians are prone to impaired heart and metabolic function <a href="https://www150.statcan.gc.ca/n1/pub/82-625-x/2019001/article/00005-eng.htm">by being overweight</a>. Not surprisingly, <a href="https://dx.doi.org/10.1249%2FMSS.0000000000000325">rates of cardiovascular events are notably increased</a> during a heat wave.</p>
<h2>Populations at risk</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/411998/original/file-20210719-15-1n6mvpx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A boy running through a fountain" src="https://images.theconversation.com/files/411998/original/file-20210719-15-1n6mvpx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411998/original/file-20210719-15-1n6mvpx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411998/original/file-20210719-15-1n6mvpx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411998/original/file-20210719-15-1n6mvpx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411998/original/file-20210719-15-1n6mvpx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411998/original/file-20210719-15-1n6mvpx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411998/original/file-20210719-15-1n6mvpx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Children are at risk for heat stroke because of their small size and immature thermoregulation system.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Jeff McIntosh</span></span>
</figcaption>
</figure>
<p>Invariably those who cannot escape the heat, namely outdoor workers and those with poor access to air-conditioning, are most at risk. Young children are also at risk because of their small body size and underdeveloped thermoregulatory system. However, advanced aging and cadiovascular disease is proving to be the biggest factor.</p>
<ul>
<li><p><strong>The elderly</strong>: Advanced aging is associated with a reduced capacity to thermoregulate, primarily attributable to a progressively compromised cardiovascular system. Interestingly, <a href="https://dx.doi.org/10.1080%2F23328940.2017.1379585">behavioral thermoregulation</a> — which includes actions like seeking shade or air conditioning — is also compromised in the elderly, such that cooling strategies are sought out less frequently compared to young adults.</p></li>
<li><p><strong>Disease</strong>: Pre-existing conditions — particularly those involving the cardiovascular system, such as heart disease and diabetes — dramatically increase the risk of heat-related illness. Often, <a href="https://doi.org/10.1111/jcpt.12294">many medications</a> used to treat these diseases can further interfere with the thermoregulatory responses to heat (for example, beta-blockers used to treat high blood pressure can inhibit the heart rate response, and diuretics can exacerbate dehydration).</p></li>
</ul>
<h2>Reducing the risk</h2>
<figure class="align-center ">
<img alt="A sign for an emergency cooling centre in Toronto" src="https://images.theconversation.com/files/411999/original/file-20210719-23-1qqvyj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/411999/original/file-20210719-23-1qqvyj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=427&fit=crop&dpr=1 600w, https://images.theconversation.com/files/411999/original/file-20210719-23-1qqvyj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=427&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/411999/original/file-20210719-23-1qqvyj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=427&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/411999/original/file-20210719-23-1qqvyj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=537&fit=crop&dpr=1 754w, https://images.theconversation.com/files/411999/original/file-20210719-23-1qqvyj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=537&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/411999/original/file-20210719-23-1qqvyj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=537&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Seeking relief from the heat is one way to help prevent heat stroke.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Frank Gunn</span></span>
</figcaption>
</figure>
<p>The primary prevention of heat illness is through immediate behaviour. Seeking air-conditioned environments, <a href="https://doi.org/10.1016/j.apergo.2014.07.013">increasing air flow through electric fans</a>, wearing light, breathable and loose-fitting clothing, keeping hydrated and avoiding strenuous activities (especially in the sun) should be the first line of defence, particularly in vulnerable populations. </p>
<p>However, assuring that the cardiovascular system is ready to take on the heat will be an integral step in curtailing the rates of heat illness. If daily exercise is not an option (or too difficult), an alternative may be to safely fight fire with fire — that is, through <a href="https://doi.org/10.1152/japplphysiol.00141.2020">heat therapy</a>. </p>
<p>Supervised heat therapy is emerging as a therapeutic tool for cardiovascular disease by improving heart and blood vessel function. It may also lead to moderate <a href="https://doi.org/10.1111/sms.12408">heat acclimation</a>, which can make it easier to deal with the heat by improving the body’s thermoregulatory response system. </p>
<p>In the end, exercise, a healthy diet, and perhaps also heat therapy (if done safely) will not only reduce the incidence for the leading cause of death worldwide (heart disease), it will also reduce the excess deaths during a heat wave. </p>
<p>Indeed, excess mortality during a heat wave is only marginally explained by incidences of outright heat stroke. Most often it is secondary from the increased cardiovascular burden associated with thermoregulatory responses to the heat.</p><img src="https://counter.theconversation.com/content/164688/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anthony Bain does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Heat stroke is a danger in extreme temperatures, but a major risk factor for dying during a heat wave is cardiovascular disease and other pre-existing health conditions.Anthony Bain, Assistant Professor, Kinesiology, University of WindsorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1637002021-07-08T12:36:51Z2021-07-08T12:36:51ZKnowing how heat and humidity affect your body can help you stay safe during heat waves<figure><img src="https://images.theconversation.com/files/410012/original/file-20210706-25-13zbvfw.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5593%2C3124&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Record-breaking triple-digit heat in Olympia, Wash., on June 28, 2021.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/PacificNorthwestHeatWave/52ee9fd2284b4ac3ab5a0f441da4a08f/photo">AP Photo/Ted S. Warren</a></span></figcaption></figure><p>Less than a month into North America’s official summer, heat waves are blistering much of the West. California and the Southwest are facing <a href="https://www.washingtonpost.com/weather/2021/07/06/california-west-heat-wave/">excessive heat watches</a> for the second time, after a <a href="https://www.climate.gov/news-features/event-tracker/record-breaking-june-2021-heatwave-impacts-us-west">mid-June heat wave</a> pushed temperatures above 100 F (38 C). </p>
<p>And in late June an intense heat dome settled over the <a href="https://www.climate.gov/news-features/event-tracker/astounding-heat-obliterates-all-time-records-across-pacific-northwest">Pacific Northwest</a> for four days, setting all-time temperature records in Oregon, Washington and British Columbia. The effects were most evident in Lytton, British Columbia, which reported a temperature of <a href="https://www.washingtonpost.com/weather/2021/06/27/heat-records-pacific-northwest/">121 F (49.5 C) on June 29</a>, far above its average high for the date of 76 F (24.4 C). A day later, the town was <a href="https://www.cnn.com/2021/07/01/americas/canada-town-evacuation-extreme-heat/index.html">engulfed by a wildfire</a>.</p>
<p>As an <a href="https://scholar.google.com/citations?user=wqDX7PUAAAAJ&hl=en">exercise physiologist</a>, I know that the human body is an amazing machine. But like all machines, it functions effectively and safely only under certain conditions. </p>
<p>People frequently debate whether wet heat in places like Florida or dry heat in desert locations like Nevada is worse. The answer is that either setting can be dangerous. Hot desert climates are stressful due to extreme temperatures, while humid subtropical climates are stressful because the body has trouble removing heat when sweat doesn’t evaporate readily. As recent events have shown, hot is hot.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1412139233565843456"}"></div></p>
<h2>The influence of humidity</h2>
<p>North America has a wide range of climates, but when people talk about heat, they often compare the Southwest and the Southeast. Some communities in the Southwest’s hot desert climates, such as Las Vegas, have average summer high temperatures over 100 F (38 C), with <a href="https://www.ncdc.noaa.gov/ghcn/comparative-climatic-data">relative humidity</a> typically around 20%. This means the air is holding about one-fifth of the maximum amount of moisture it can hold at that temperature and pressure. </p>
<p>In contrast, Southeast locations like Orlando, Florida, typically have average temperatures around 90 F (32.2 C), with humidity regularly approaching 80%. Looking only at temperature, the desert clearly is hotter on average. </p>
<p>However, it’s also important to consider how heat affects the body. Weather reports often do this using the <a href="https://www.weather.gov/ama/heatindex">heat index</a>, which calculates how the human body perceives conditions factoring in humidity as well as heat. </p>
<p>Sweating is your body’s primary way of cooling you off. When sweat evaporates away from your skin, it <a href="https://www.weather.gov/oun/safety-summer-heathumidity">takes heat with it</a>. But when humidity is high, the air already holds a lot of moisture, so the sweat remains on your skin. As it saturates clothing and drips from the body, it can remove only a small amount of heat compared with the cooling that comes with the evaporation of sweat. </p>
<p>As a result, when we account for humidity, the heat exposures people experience in Las Vegas and Orlando are very similar. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Table showing hazardous heat/humidity combinations." src="https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=351&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=351&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=351&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=441&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=441&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=441&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The National Weather Service’s Heat Index shows the risk of activity based on heat plus humidity.</span>
<span class="attribution"><a class="source" href="https://dps.mn.gov/divisions/hsem/weather-awareness-preparedness/Pages/severe-weather-heat.aspx">NOAA</a></span>
</figcaption>
</figure>
<h2>Adapting people and places to heat stress</h2>
<p>As people go through their daily lives, their bodies work continuously to maintain a temperature close to a normal level of about 98.6 F (37 C). In regions that regularly experience high heat stress, such as the Southeast and Southwest, most buildings and homes now have air conditioning, which helps people maintain healthy temperatures.</p>
<p>But in areas where heat is unusual, such as the Pacific Northwest, many buildings and residences <a href="https://www.seattletimes.com/seattle-news/health/with-more-heat-waves-expected-in-the-future-seattles-long-term-care-facilities-weigh-the-need-for-air-conditioning/">lack cooling</a>. As a result, people are exposed to higher heat for longer periods of time during events like the region’s late June heat wave than they would be in regions where hot weather is the norm.</p>
<p>Just as buildings and residences in areas chronically exposed to heat are equipped with ceiling fans and air conditioning, bodies that are regularly exposed to heat can <a href="https://www.cdc.gov/niosh/mining/userfiles/works/pdfs/2017-124.pdf">acclimatize</a>, or adapt and improve their ability to cool. This starts to occur with the first heat exposure – for example, the beginning of fall sports practices in August – but take weeks of regular exposure to reach maximal levels. </p>
<p>One of the first things our bodies do in adapting to heat is to <a href="http://dx.doi.org/10.1111/sms.12408">produce more plasma</a> – the watery portion of blood. This enables our circulatory systems to move heat to the skin more effectively so that sweating can remove it from the body.</p>
<p>We also begin sweating earlier than people who are not acclimatized to heat, and our <a href="https://doi.org/10.3390/nu13061807">maximal sweat rate increases</a>. These adaptations improve our bodies’ ability to dissipate heat to the environment. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Workplace flyer with tips for acclimatizing to heat." src="https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1285&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1285&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1285&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1615&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1615&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1615&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Outdoor workers should build up to a full day in the heat to allow their bodies to acclimatize to it.</span>
<span class="attribution"><a class="source" href="https://www.cdc.gov/niosh/topics/heatstress/pdf/NIOSH_HeatStressInfographic_print-508.pdf">CDC</a></span>
</figcaption>
</figure>
<p>Behavior changes are another way of adapting to heat stress. Since midday is typically the hottest part of the day, it makes sense to avoid physical work and exercise then. When people are active, their bodies break down nutrients – carbohydrates, fats and protein – into energy. This powers movement and also generates metabolic heat, which adds to the body’s heat stress.</p>
<p>Taking advantage of shade is another important strategy. Heat radiating from the Sun adds to the stress produced by warm air temperatures. Staying in the shade can significantly reduce the external heat load on <a href="https://blogs.cdc.gov/niosh-science-blog/2021/05/07/heat-stress-2021/">people who have to be outdoors during hot spells</a>.</p>
<p>Many of the <a href="https://doi.org/10.1136/bmj.n1696">hundreds of deaths and hospitalizations</a> that experts have attributed to the recent heat dome in the Northwest probably reflect that buildings there were less equipped to keep people cool than in hotter regions, and residents were less acclimatized to heat.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Q2RQjtucG3M?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">2020 was Phoenix’s hottest year on record, with 53 days reaching at least 110 F.</span></figcaption>
</figure>
<h2>The old and young are most vulnerable</h2>
<p>A healthy adult body can acclimatize to heat, but older people and children are less able to adjust. As people age, their cardiovascular systems change in ways that cause them to <a href="https://www.physio-pedia.com/Cardiovascular_Considerations_in_the_Older_Patient">pump blood less effectively</a>. This reduces the body’s ability to move heat to the skin to be transferred to the environment. </p>
<p>[<em>The Conversation’s science, health and technology editors pick their favorite stories.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-favorite">Weekly on Wednesdays</a>.]</p>
<p><a href="http://dx.doi.org/10.1080/02640414.2015.1055291">Children</a> and <a href="https://www.nih.gov/news-events/news-releases/heat-related-health-dangers-older-adults-soar-during-summer">older adults</a> may also have less active sweat responses, which can reduce their potential to cool off through sweating. </p>
<p>Humans can tolerate most areas of the Earth, but extreme heat requires extra steps. If there’s a heat wave in your local forecast, seek out shade and begin to acclimatize by increasing your activity gradually when things get too hot. Drink more fluids to account for <a href="https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/water/art-20044256">increased fluid loss from sweat</a>, while also making sure <a href="https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/water/art-20044256">not to overhydrate</a>. And avoid outdoor activity during the hottest hours of the day if possible. </p>
<p>Whether heat waves are humid or dry, they are health threats that everyone should take seriously.</p><img src="https://counter.theconversation.com/content/163700/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>JohnEric W. Smith does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Which is worse, dry heat or wet heat? Both, says an exercise physiologist.JohnEric W. Smith, Associate Professor of Exercise Physiology, Mississippi State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1396812020-06-04T06:34:21Z2020-06-04T06:34:21ZHeading back to the gym? Here’s how you can protect yourself and others from coronavirus infection<figure><img src="https://images.theconversation.com/files/339674/original/file-20200604-130929-iutdtd.jpg?ixlib=rb-1.1.0&rect=8%2C0%2C5455%2C3637&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>With coronavirus restrictions gradually lifting across the country, we’re now able to resume many of our regular activities. </p>
<p>A lot of us might have been particularly keen to get back to the gym, which is <a href="https://www.9news.com.au/national/coronavirus-south-australia-reopening-restrictions-ease-pubs-gyms-cafes/abc6eaee-0c30-4eb8-9b20-bcc637c15c5e">now an option</a> in some Australian states, and <a href="https://www.abc.net.au/news/2020-06-02/nsw-coronavirus-restrictions-on-gyms-to-be-lifted-from-june-13/12310984">not far off</a> in others. </p>
<p>So, how can we protect ourselves and other people from COVID-19 infection when we return to the gym? </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/working-out-at-home-works-for-women-so-well-they-might-not-go-back-to-gyms-138111">Working out at home works for women – so well they might not go back to gyms</a>
</strong>
</em>
</p>
<hr>
<h2>How are gyms unique?</h2>
<p>First it’s important to understand gyms are a bit different to other places where people might gather.</p>
<p>Gyms are generally indoors, which means they don’t have the luxury of open air. We know SARS-CoV-2, the coronavirus that causes COVID-19, is more likely to spread <a href="https://www.businessinsider.com.au/coronavirus-risk-higher-tight-indoor-spaces-with-little-air-flow-2020-5?r=US&IR=T">indoors than outdoors</a>.</p>
<p>So there may be a need for individual gyms to consider specific limitations on the number of people in a given space, especially if the ventilation is poor. </p>
<p>The huffing and puffing associated with vigorous exercise may cause you to <a href="https://www.health.nsw.gov.au/Infectious/covid-19/Pages/high-risk-interventions-respiratory-physiotherapy.aspx">cough or splutter</a>, which can see infectious particles propelled, contaminating the environment. So keeping your distance from others is especially important in gyms.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/339676/original/file-20200604-130903-o38epw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/339676/original/file-20200604-130903-o38epw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/339676/original/file-20200604-130903-o38epw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/339676/original/file-20200604-130903-o38epw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/339676/original/file-20200604-130903-o38epw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/339676/original/file-20200604-130903-o38epw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/339676/original/file-20200604-130903-o38epw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Gym classes will be smaller for the time being.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>SARS-CoV-2 appears to survive for longer periods on <a href="https://www.thelancet.com/journals/lanmic/article/PIIS2666-5247(20)30003-3/fulltext">smooth, hard surfaces</a>, such as stainless steel, compared to paper or cardboard, for example. Gyms tend to have a lot of equipment with these smooth surfaces. This makes cleaning equipment very important.</p>
<p>People in the gym are likely to be sweating more than the average person. While SARS-CoV-2 is primarily spread through <a href="https://theconversation.com/coronavirus-why-should-we-stay-1-5-metres-away-from-each-other-134029">respiratory droplets</a>, when you sweat, you often touch your face. </p>
<p>You may be carrying the infectious droplets you’ve picked up from surfaces on your hands, and could risk infecting yourself in this way – or infecting others if you are infected.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/from-spit-to-scrums-how-can-sports-players-minimise-their-coronavirus-risk-139034">From spit to scrums. How can sports players minimise their coronavirus risk?</a>
</strong>
</em>
</p>
<hr>
<p>Finally, shared amenities in gyms such as drinking fountains, change rooms, showers and even hair-dryers can also increase the risk of virus transmission.</p>
<p>Drinking fountains generally have a smooth surface and you need to use your hands to operate them, providing a potential <a href="https://www.coronavirus.tas.gov.au/keeping-yourself-safe/food-and-drinks">route for transmission</a>. Likewise, objects in change rooms and showers may be frequently touched. And hair-dryers have the potential to propel droplets, much like fans or <a href="https://wwwnc.cdc.gov/eid/article/26/7/20-0764_article">air-conditioners</a>.</p>
<h2>Responsibilities for gyms</h2>
<p>Several indoor sports facilities were implicated in a COVID-19 outbreak in South Korea which saw 112 people infected. An <a href="https://wwwnc.cdc.gov/eid/article/26/8/20-0633_article">investigation</a> suggested large class sizes, small spaces, and intensity of the workouts may have contributed to the outbreak. </p>
<p>We obviously don’t want that to happen here. So as gyms reopen, staff should ensure the number of patrons doesn’t exceed what’s allowed. Different states have slightly different rules around this. </p>
<p>For example, in <a href="https://www.abc.net.au/news/2020-05-30/what-coronavirus-restrictions-are-changing-june-1-by-state/12296664">South Australia</a>, gyms reopened this week to a maximum of 80 patrons, but only ten in a group fitness class.</p>
<p>When gyms reopen in <a href="https://www.abc.net.au/news/2020-06-03/nsw-coronavirus-restrictions-on-gyms-explained/12312108">New South Wales</a> on June 13, a maximum of 100 people will be allowed in a large gym, and similarly a maximum of ten in one class.</p>
<p>Gyms have been encouraged to take bookings to ensure people don’t need to be turned away at the door.</p>
<p>Gyms will also need to increase their cleaning practices and collect contact details from patrons to ensure they can follow up in the event of a positive case of COVID-19.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-keep-a-coronavirus-safe-distance-when-youre-jogging-or-cycling-136235">How to keep a coronavirus-safe distance when you're jogging or cycling</a>
</strong>
</em>
</p>
<hr>
<h2>What you can do</h2>
<p>There are a number of things you can do to protect yourself and others when you’re back in the gym. The obvious top three are not going to the gym if you’re unwell (any cold or flu like symptoms), hand hygiene and maintaining sufficient distance from others.</p>
<p>But here are some specific tips:</p>
<ul>
<li><p><a href="https://www.who.int/gpsc/tools/GPSC-HandRub-Wash.pdf?ua=1">wash your hands or use hand sanitiser</a> when you enter and leave the gym</p></li>
<li><p><a href="https://theconversation.com/how-to-clean-your-house-to-prevent-the-spread-of-coronavirus-and-other-infections-133912">clean</a> equipment before and after you use it. Wash or sanitise your hands after you’ve cleaned the equipment (gyms can help by making sure cleaning materials and hand sanitiser are readily available)</p></li>
<li><p>avoid <a href="https://pubmed.ncbi.nlm.nih.gov/20458095/">touching your face</a> or mouth during your workout</p></li>
<li><p>increase the space between yourself and others to avoid accidentally getting closer while you exercise, especially during classes where your contact time with others may be longer</p></li>
</ul>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/339678/original/file-20200604-130951-1igbcnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/339678/original/file-20200604-130951-1igbcnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/339678/original/file-20200604-130951-1igbcnc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/339678/original/file-20200604-130951-1igbcnc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/339678/original/file-20200604-130951-1igbcnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/339678/original/file-20200604-130951-1igbcnc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/339678/original/file-20200604-130951-1igbcnc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">It’s a good idea to clean the gym equipment before and after you use it.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<ul>
<li><p>bring your own water bottle to avoid drinking from fountains or refilling water (water stations may be closed anyway)</p></li>
<li><p>change and shower at home if possible (shower facilities may be closed anyway)</p></li>
<li><p>go to the gym during off-peak or quieter times where possible.</p></li>
</ul>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-stay-fit-and-active-at-home-during-the-coronavirus-self-isolation-134044">How to stay fit and active at home during the coronavirus self-isolation</a>
</strong>
</em>
</p>
<hr>
<p>At present, community transmission in Australia is low. But everyone has a role to play in keeping numbers low, particularly as we start returning to “normal”. </p>
<p>Taking these measures will help reduce the risk as much as possible, and hopefully ensure gyms, and the rest of society, can remain open.</p><img src="https://counter.theconversation.com/content/139681/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brett Mitchell is affiliated with the University of Newcastle, Editor-in-Chief (Infection, Disease and Health), member of the Infection Control Expert Advisory Group (Advising AHHPC), member of the COVID Evidence Taskforce Leadership Group, Fellow of the Australian College of Nursing and Australasian College for Infection Prevention and Control. Brett Mitchell has received funding from the NHMRC, HCF Foundation, Australian College of Nursing, Rosemary Norman Foundation, Australasian College for Infection Prevention and Control, Cardinal Health, MSD, and the Commonwealth (Innovations Connections).</span></em></p><p class="fine-print"><em><span>Philip Russo is the President of the Australasian College for Infection Prevention and Control. He is a member of the COVID Evidence Taskforce Steering Committee, the Infection Control Expert Group to the Department of Health, the Australian Strategic and Technical Advisory Group on AMR, the Healthcare Associated Infection Advisory Committee to the Australian Commission on Safety and Quality in Health Care, and a member of the Australian College of Nursing. He is also the recipient of a NHMRC Early Career Fellowship, and has received research funding from the Rosemary Norman Foundation, Cardinal Health, Australian College of Nursing and the Cabrini Institute</span></em></p>If you’re itching to get back to the gym when it re-opens, here’s what you can do to protect yourself and others from COVID-19.Brett Mitchell, Professor of Nursing, University of NewcastlePhilip Russo, Associate Professor, Director Cabrini Monash University Department of Nursing Research, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1311352020-02-28T03:50:44Z2020-02-28T03:50:44ZWhy do I sweat so much?<figure><img src="https://images.theconversation.com/files/317699/original/file-20200228-24685-18o54ey.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1000%2C666&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-man-horror-looking-sweaty-shirt-447385717">Shutterstock</a></span></figcaption></figure><p>If you’re hot and sticky even before your daily commute, you might ask why you sweat so much.</p>
<p>Sweating is usually the body’s way of stopping you overheating. But for some people, sweating becomes a problem. Either they sweat for no obvious reason or (as <a href="https://www.theatlantic.com/health/archive/2019/11/prince-andrew-says-he-once-didnt-sweat-is-that-possible/602227/">Prince Andrew admitted last year</a>) not at all.</p>
<p>So why do some people sweat more than others? And what can you do about excess sweating?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/anhidrosis-why-some-people-apparently-like-prince-andrew-just-cant-sweat-127280">Anhidrosis: why some people – apparently like Prince Andrew – just can't sweat</a>
</strong>
</em>
</p>
<hr>
<h2>Remind me again, why do we sweat?</h2>
<p>Humans need to regulate their internal body temperature to keep it constant, even when the environmental temperature rises, perhaps on a hot day, sitting in a hot-tub or running for the bus.</p>
<p>That’s because a rise in internal body temperature can lead to our organs overheating, fatigue, heat exhaustion and heat stroke.</p>
<p>Preventing severe heat gain requires a careful balance between the heat our body produces (from everyday metabolism), heat from the environment and the heat our body loses.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-skin-is-a-very-important-and-our-largest-organ-what-does-it-do-91515">The skin is a very important (and our largest) organ: what does it do?</a>
</strong>
</em>
</p>
<hr>
<p>Our bodies are well-designed for this. We have special temperature sensors in our skin and central nervous system (brain and spinal cord) that send signals to the body’s thermostat in the brain to alert it to increases in body temperature.</p>
<p>The body’s largest organ, the skin, is also designed to remove heat from the body. The most noticeable way is losing heat via evaporating sweat.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-what-happens-in-the-body-when-we-sweat-85831">Curious Kids: What happens in the body when we sweat?</a>
</strong>
</em>
</p>
<hr>
<h2>How does sweating cool us down?</h2>
<p>When our skin or core body temperature rises sufficiently, the thermostat in the brain sends impulses via our central nervous system to increase blood flow to the skin. The thermostat also activates the sweat glands. </p>
<p>Our sweat glands release droplets onto our skin that become vapour when the blood flowing through the skin passes underneath. </p>
<p>As the sweat vaporises, energy (in the form of heat) passes into the environment, cooling the blood. This cooled blood gets circulated back to the heart and brain, and cools our core body temperature.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/317694/original/file-20200227-24651-ykhocw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/317694/original/file-20200227-24651-ykhocw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/317694/original/file-20200227-24651-ykhocw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=557&fit=crop&dpr=1 600w, https://images.theconversation.com/files/317694/original/file-20200227-24651-ykhocw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=557&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/317694/original/file-20200227-24651-ykhocw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=557&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/317694/original/file-20200227-24651-ykhocw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=700&fit=crop&dpr=1 754w, https://images.theconversation.com/files/317694/original/file-20200227-24651-ykhocw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=700&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/317694/original/file-20200227-24651-ykhocw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=700&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The body loses excess heat via evaporation.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/perspiring-anatomical-human-skin-layers-cross-1067095673">from www.shutterstock.com</a></span>
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</figure>
<p>This is why a day in the sun can feel so draining. Your body is working much harder and using much more energy to keep you cool.</p>
<p>By preventing our organs from overheating, sweat not only keeps us healthy, it also allows us to enjoy (or tolerate) the hot Australian summer. </p>
<p>So it’s important to stay hydrated on a hot day so your body can produce and replace the volume of sweat necessary to keep you cool.</p>
<h2>OK, but why do I sweat so much?</h2>
<p>You might find yourself sweating more or less than usual for a number of reasons, other than it being a hot day.</p>
<p><strong>Exercise</strong></p>
<p>Exercise improves our ability to produce sweat and keep cool. People who exercise regularly (particularly in the heat) can <a href="https://journals.physiology.org/doi/full/10.1152/japplphysiol.00495.2010">produce more sweat</a> during exercise. This helps our bodies perform longer, with less physiological strain.</p>
<p>So many of the Australian Olympic athletes will undergo a period of heat acclimatisation in the lead up to Tokyo 2020.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-is-japans-olympic-marathon-shifting-cities-to-avoid-the-heat-a-sports-physiologist-explains-126189">Why is Japan's Olympic marathon shifting cities to avoid the heat? A sports physiologist explains</a>
</strong>
</em>
</p>
<hr>
<p><strong>Stress</strong></p>
<p>Ever notice you become sweaty when you are stressed? A different type of sweat gland, the <a href="https://www.mayoclinic.org/diseases-conditions/hyperhidrosis/multimedia/sweat-glands/img-20007980">apocrine sweat glands</a>, are associated with hair follicles and often respond to <a href="https://www.ncbi.nlm.nih.gov/pubmed/31128655">emotional stress</a>. </p>
<p>This type of sweat combines with bacteria on your skin and causes body odour.</p>
<p><strong>Menopause</strong></p>
<p><a href="https://www.sciencedirect.com/science/article/abs/pii/S0025619611618119?via%3Dihub">Up to 75% of women</a> experience acute bouts of excessive sweating during menopause, called a hot flush.</p>
<p>The <a href="https://physoc.onlinelibrary.wiley.com/doi/epdf/10.1113/JP271456">amount of sweat</a> produced during a two to three minute hot flush can be similar to the amount produced during exercise.</p>
<p>Most people think hot flushes are caused by increases in core body temperature. But <a href="https://journals.lww.com/menopausejournal/fulltext/2019/09000/Is_core_temperature_the_trigger_of_a_menopausal.12.aspx">our research</a> suggests this might not be the case.</p>
<p><strong>Drinking alcohol</strong></p>
<p>Having a couple of drinks with friends may also <a href="https://www.sciencedirect.com/science/article/abs/pii/S0741832905001503?via%3Dihub">increase the sweat response</a>. Alcohol raises your heart rate and causes the blood vessels in your skin to relax and widen. This increases skin redness and your sweat rate, which can actually lead to decreases in body temperature.</p>
<h2>So, what can I do about it?</h2>
<p>Excessive sweating (<a href="https://www1.racgp.org.au/newsgp/clinical/what-is-hyperhidrosis">hyperhidrosis</a>) can happen in unusual situations such as in a cooler climate or with seemingly no cause.</p>
<p>Although it can be embarrassing and uncomfortable, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4012678/">there are ways to treat it</a>, which you can discuss with your doctor. </p>
<p>One option is to use an antiperspirant with aluminium or topical aluminium salts, which blocks the sweat glands from releasing sweat onto the skin.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-do-men-really-sweat-more-than-women-73903">Health Check: do men really sweat more than women?</a>
</strong>
</em>
</p>
<hr>
<p>A longer-term option may be <a href="https://www.ncbi.nlm.nih.gov/pubmed/19222249">injecting Botulinum toxin</a> (commonly known as Botox) into the skin. This paralyses the injected area (such as the armpits, hands and feet) and prevents the activation of sweat glands. </p>
<p>Other options include using low frequency electrical stimulation (<a href="https://dermnetnz.org/topics/iontophoresis/">iontophoresis</a>), prescription drugs and although controversial, surgery.</p>
<p>For menopausal women, <a href="https://www.ncbi.nlm.nih.gov/pubmed/27163520">we have shown</a> closely supervised exercise training can improve temperature regulation, leading to fewer and less severe hot flushes.</p>
<p>This training involved 16 weeks of supervised, progressive moderate-intensity aerobic exercise, such as treadmill and cycling exercise, for up to one hour for three to five days a week.</p>
<h2>In a nutshell</h2>
<p>In the end, sweating is usually our body’s natural way to protect us from overheating. But if excess sweating is a problem, see your doctor who will outline which treatment options are best for you.</p><img src="https://counter.theconversation.com/content/131135/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Sweating is usually our body’s way of stopping us from overheating. But if excess sweating is a problem for you, there’s help.Tom Bailey, Research Fellow, The University of QueenslandFaith Pizzey, PhD Student in Cerebrovascular Physiology, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1272802019-11-18T21:20:47Z2019-11-18T21:20:47ZAnhidrosis: why some people – apparently like Prince Andrew – just can’t sweat<figure><img src="https://images.theconversation.com/files/302295/original/file-20191118-66973-137v649.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Prince Andrew during the recent BBC interview.</span> <span class="attribution"><span class="source">BBC/Mark Harrison</span></span></figcaption></figure><p>Sweating is a controversial topic at the moment. In his <a href="https://www.independent.co.uk/news/uk/home-news/prince-andrew-interview-latest-jeffrey-epstein-bbc-paedophile-a9206661.html">extraordinary</a> recent <a href="https://www.bbc.co.uk/iplayer/episode/m000c1j4/newsnight-prince-andrew-the-epstein-scandal-the-newsnight-interview">BBC interview</a>, Prince Andrew <a href="https://www.youtube.com/watch?v=sE9iJPEuYHE">dismissed</a> some of the <a href="https://www.bbc.co.uk/news/uk-50446065">allegations</a> made against him by Virginia Giuffre (known previously as Virginia Roberts) on the grounds that he couldn’t sweat at the time – she had claimed he had been <a href="https://www.bbc.co.uk/news/uk-50451953">“profusely sweating”</a>. During the interview, Prince Andrew, who has <a href="https://www.bbc.co.uk/news/uk-50446065">categorically denied</a> all of the claims against him, said:</p>
<blockquote>
<p>I didn’t sweat at the time because I had suffered what I would describe as an overdose of adrenaline in the Falklands War, when I was shot at … it was almost impossible for me to sweat.</p>
</blockquote>
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<p>But what makes us sweat, why do we do it – and can some conditions prevent us from doing it at all?</p>
<p>The human body is an amazing entity and responds to thousands of internal and external signals every day. These responses enable us to survive in rapidly changing conditions.</p>
<p>The skin is the largest and heaviest organ of the human body. It is calculated to <a href="https://www.sciencedirect.com/science/article/pii/S0022202X15503679">weigh</a> approximately three to 4.5kg and, over the course of your life, you will lose about <a href="https://pubs.acs.org/doi/full/10.1021/es103894r">35kg</a> of skin. Skin constantly repairs and replaces itself and performs many functions. It protects the body against pathogens, provides insulation, synthesises vitamin D, provides sensation and most importantly regulates temperature.</p>
<p>The regulation of temperature is complex. Nerve fibres detect the temperature of whatever is in contact with the skin and relay this information to the brain, which makes a decision about what to do next – take off a jumper or put on a coat. But there are also more primitive and uncontrollable responses.</p>
<p>The skin is covered in most places by hair. When cold, the brain causes these hairs to stand on end, trapping a layer of insulating air next to the skin. Conversely, when it’s too hot, the body sweats, producing fluid from the approximately 4m sweat glands in the skin to help heat evaporate away from the body – cooling us down.</p>
<h2>What is sweating?</h2>
<p>Sweating is the release of a water-like fluid from special glands in the skin to help regulate body temperature. The fluid is approximately 99% water but also <a href="https://academic.oup.com/chemse/article/35/2/101/483325">contains</a> electrolytes, fatty acids, urea (as found in urine) and lactic acid. Many of these chemicals are now being <a href="https://journals.humankinetics.com/view/journals/ijsnem/18/5/article-p457.xml">analysed</a> to detect health and <a href="http://pdfs.semanticscholar.org/3c33/33413c4cb5674f56e3783a9105a6c7a2d773.pdf">hydration</a> levels, and assist in diagnosing diseases such as <a href="https://www.sciencedirect.com/science/article/pii/S0022347608003983">cystic fibrosis</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/from-perspiration-to-world-domination-the-extraordinary-science-of-sweat-62753">From perspiration to world domination – the extraordinary science of sweat</a>
</strong>
</em>
</p>
<hr>
<p>The body is composed of up to 75% water and the loss of as little as 1% of this can cause dehydration. A 10% loss, meanwhile, can lead to life-threatening changes to the body.</p>
<p>A sedentary adult loses approximately <a href="https://www.nature.com/articles/ejcn2009111">450ml</a> of water through invisible perspiration a day, while athletes in hot, dry environments can produce <a href="https://www.ncbi.nlm.nih.gov/books/NBK236237/">1,200ml</a> of sweat per hour. Total water loss can often be between two and three litres a day through sweating, breathing and other routes in a sedentary adult. But in warmer climates and with activity, these rates can increase hugely.</p>
<h2>How does sweating work?</h2>
<p>Sweating is usually initiated by an increase in body temperature from the normal 37C. When the body senses it is getting too hot, an area of the brain called the <a href="https://www.ncbi.nlm.nih.gov/books/NBK507838/">hypothalamus</a> controls the response. It does this through the sympathetic nervous system – also known as the “fight or flight” mechanism, because it also helps us fight for our lives or run away when we’re in danger. In this case, it triggers nervous impulses to release neurotransmitters (chemicals) that activate the sweat glands.</p>
<p>The main neurotransmitter involved in controlling sweating is called acetylcholine and its presence causes sweat glands to produce sweat – although a few also respond to a different neurotransmitter called adrenaline. The reason some respond to different neurotransmitters is to do with the receptors they have on their surface. Think of this as a lock and key – only the correct neurotransmitter (key) can fit in the receptor (lock) to cause the sweat gland to function.</p>
<p>In stressful situations, cold sweats are usually mediated by adrenaline. This is because the adrenaline causes the blood vessels to narrow and a few sweat glands to become active – producing a drop in skin temperature and a cold sweat. Most temperature-related sweating, however, is controlled by acetylcholine and the presence of adrenaline would not have any consequence on the function of these sweat glands.</p>
<h2>Does everyone sweat?</h2>
<p>Sweating is normal and just about everyone does it. Some people, however, do it more or less than others.</p>
<p>A complete absence of sweating is called anhidrosis. It can occur in particular areas of the body or be global – where more than 80% of the body has no ability to sweat. The causes are usually damage or pathology of the nervous system, or they may be inherited, such as in the case of <a href="https://www.nhs.uk/conditions/sjogrens-syndrome/">Sjogrens Syndrome</a>. Some individuals suffer from hypohidrosis which is a reduction in sweating and can be indicative of dehydration.</p>
<p>Regarding Prince Andrew’s claim, an excess or continual exposure to adrenaline is not widely recognised as causing a lack of sweating in humans. However, there is some data in <a href="https://www.ncbi.nlm.nih.gov/pubmed/6359664">horses</a> that has suggested that exposure to extreme temperatures may result in damage to the type of sweat glands that respond to adrenaline.</p>
<p>Similarly, the fact that the central nervous system, and parts of it that are linked to controlling the “fight or flight” response system, can also be involved or damaged in psychological trauma, means it is impossible to rule out this possibility without more information. There are a number of reports of individuals who have developed an idiopathic (unexplained) inability to sweat during <a href="https://pdfs.semanticscholar.org/f593/bab5d37b0f21754a17eb9ab28e29b8c231a9.pdf">military</a> and extreme training. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/302252/original/file-20191118-66957-1vnk0km.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/302252/original/file-20191118-66957-1vnk0km.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/302252/original/file-20191118-66957-1vnk0km.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/302252/original/file-20191118-66957-1vnk0km.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/302252/original/file-20191118-66957-1vnk0km.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/302252/original/file-20191118-66957-1vnk0km.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/302252/original/file-20191118-66957-1vnk0km.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hypohidrosis?</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sweaty-spot-on-shirt-because-heat-447385741">Shutterstock</a></span>
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<p>At the opposite end of the spectrum is hyperhidrosis, which is excessive sweating. This condition can be systemic (body-wide) or localised. It is known that axillary hyperhidrosis (excessive armpit sweating) affects approximately <a href="https://www.ncbi.nlm.nih.gov/pubmed/15280843">3%</a> of the US population. Interference of tumours and other <a href="https://casereports.bmj.com/content/2013/bcr-2013-009732">pathologies</a> with the central nervous system can result in this symptom.</p>
<p>While sweating is seen to have its primary role in reducing body temperature, it is becoming clear that what is contained in sweat is far more interesting. Sweat even appears to be able to convey a person’s emotional state.</p>
<p>Women who were exposed to <a href="https://academic.oup.com/chemse/article/31/5/415/395942">sweat samples</a> that were collected from donors who were exhibiting fear while watching videos, for example, performed better in word association tasks than those women who were exposed to sweat which was produced by people watching neutral videos or samples that had no sweat on them at all. The sweat appears to contain a “signal” that suggests the person was undertaking a task that produced a heightened emotional or fearful state.</p>
<p>We may never know the truth about Prince Andrew’s sweating, but it’s something we all do and rely on – and researchers will continue to unlock its secrets for years to come.</p><img src="https://counter.theconversation.com/content/127280/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam Taylor is affiliated with the Anatomical Society. </span></em></p>In his recent interview, Prince Andrew claimed that he had stopped sweating. Here’s what the research says about how and why our bodies do it.Adam Taylor, Professor and Director of the Clinical Anatomy Learning Centre, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1194472019-09-12T11:06:41Z2019-09-12T11:06:41ZAn artist’s journey into the science of sweat<figure><img src="https://images.theconversation.com/files/289506/original/file-20190826-8845-14ap2e1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sweat keeps the human body cool, but why does it stink?</span> <span class="attribution"><span class="source">AP Photo/Seth Wenig</span></span></figcaption></figure><p>During steamy days, a body’s physiological response may cause you to wrinkle your nose: the smell of what many people associate with sweat.</p>
<p>In reality, sweat itself doesn’t have much scent. Surprisingly, the distinctive smell of human sweat results from a cocktail of microorganisms, living in and on our bodies, that metabolize sweat into <a href="https://doi.org/10.1016/j.tim.2013.03.002">body odor</a>. Bacteria not only inhabit humans but, in some respects, <a href="https://doi.org/10.1158/0008-5472.CAN-16-2929">define us</a> because they play such an <a href="https://www.nih.gov/news-events/news-releases/nih-human-microbiome-project-defines-normal-bacterial-makeup-body">important role in our health</a>. Who we are as individuals may have a great deal to do with our personal collection of bacteria.</p>
<p><a href="http://www.paulvanouse.com">I’m an artist who focuses on science</a>. I became intrigued by sweat after considering the implications of <a href="https://www.nature.com/articles/nm.4517">the human microbiome</a>, the hundreds of microorganisms that inhabit our bodies. </p>
<p>For the last five years, I have worked on an elaborate <a href="https://www.burchfieldpenney.org/exhibitions/exhibition:01-11-2019-03-31-2019-paul-vanouse-labor/">scent-based art installation called “Labor”</a> to recreate the odor many people associate with sweat and give audiences a new way to “see” and understand smell. My art installation focuses on bodily secretions, bacteria that create odor and how those scents shape our perceptions of ourselves and each other.</p>
<h2>Work and sweat. Cause and effect</h2>
<p>There is an unusual laboratory in Helsinki, Finland, founded to host creative interdisciplinary practices called “bio-art.” As part of an artist’s residency, I worked at <a href="https://www.aalto.fi/en/biofilia">Biofilia</a> at Aalto University to recreate the scent people associate with sweat. For inspiration and perspiration, I used myself as a laboratory subject, spending plenty of time in the legendary Finnish saunas.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/289486/original/file-20190826-8880-1j4exjw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289486/original/file-20190826-8880-1j4exjw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289486/original/file-20190826-8880-1j4exjw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289486/original/file-20190826-8880-1j4exjw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289486/original/file-20190826-8880-1j4exjw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289486/original/file-20190826-8880-1j4exjw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289486/original/file-20190826-8880-1j4exjw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The art installation ‘Labor’ created the aroma of sweat without a human body.</span>
<span class="attribution"><a class="source" href="https://www.paulvanouse.com/labor.html">Burchfield Penny Art Center. Photo by Tullis Johnson.</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>In the human body, <a href="https://doi.org/10.1371/journal.pbio.1002533">bacterial cells far outnumber human cells</a>. They fill our guts, enable digestion, affect immune reactions and influence <a href="https://doi.org/10.1371/journal.ppat.1003726">appetites and emotional states</a>. </p>
<p>Specific bacteria metabolize sweat to produce an aroma or scent that results from warm temperatures, stress or physical effort. Sweat is a smell that can signal work, such as toiling in a “sweatshop,” or hard manual labor made even harder by poor working conditions. Idioms like “by the sweat of one’s brow” or “sweat equity” are some of the ways we define work, even as work can define <a href="https://doi.org/10.1007/s10869-019-09627-w">us and provide a sense of self-worth</a>. </p>
<p>During the Industrial Revolution, machines began to <a href="https://www.britannica.com/story/the-rise-of-the-machines-pros-and-cons-of-the-industrial-revolution">replace human workers in factories</a>. More recently, microbes have begun to replace and augment these machines. Today, microbes are <a href="https://www.uk-cpi.com/blog/10-everyday-uses-of-biotechnology">used to produce a wide range of products</a> including enzymes, foods, beverages, feedstocks, fuels and pharmaceuticals. </p>
<p>Three genus of bacteria are key in producing human scent – <a href="https://doi.org/10.1016/j.tim.2013.03.002"><em>Staphylococcus</em>, <em>Corynebacterium</em> and <em>Propionibacterium</em></a>. These bacteria metabolize sweat, a human byproduct, to produce a waste product, which has a distinct odor. Two types of glands – <a href="https://www.mayoclinic.org/diseases-conditions/hyperhidrosis/multimedia/sweat-glands/img-20007980">eccrine and apocrine</a> – produce sweat. Eccrine glands excrete a fluid, mainly water and salt, that helps to regulate body temperature. Apocrine glands excrete a denser, milky fluid often resulting from emotional stress. It is the bacterial breakdown of apocrine sweat that <a href="https://www.mayoclinic.org/diseases-conditions/sweating-and-body-odor/symptoms-causes/syc-20353895">produces the most pungent body odors</a>. </p>
<p><em>Staphylococcus</em> transforms amino acids in sweat into various acids, a smell I describe as “<a href="https://doi.org/10.1111/1574-6941.12054">high-pitched,” or the dirty sock smell of a locker room</a>. </p>
<p><em>Corynebacteria</em> alters scentless human steroids and other molecules in sweat to produce smelly steroids and sulfur compounds. I affectionately named these odors “white-collar labor.” Likewise, <em>Propionibacterium</em> metabolize amino acids to produce an acrid odor, funky and vinegary.</p>
<h2>The art and science of smell</h2>
<p>My research began by defining human skin bacteria associated with odors and learning how to grow them. The scientific literature is sparse, as much of this research is carried out by <a href="https://cen.acs.org/articles/90/i27/Deodorants-Antiperspirants.html">deodorant and antiperspirant</a> industries, which often don’t publish their results. </p>
<p>Next, I isolated my sweat by capturing bacteria from my armpits in sterile gauze, filtering it and incubating it in dozens of heat and atmospheric conditions. Then I designed a bioreactor, similar to fermenters that brew beer, except they are built to enable more varied types of biochemical reactions with microbes. Finally, I experimented with liquid cultures that encouraged bacteria to thrive and produce fragrant waste products. </p>
<p>The concept of my artwork “Labor” is that microorganisms create the “vulgar odors” of sweat, a byproduct of production and labor reminiscent of “sweatshops” and factories of the 19th and 20th centuries. The exhibit contains several large glass bioreactors, each populated with one of three strains of bacteria. The soup in each container produced the smell of sweat, odors that collected in a central glass enclosure where a white T-shirt hung. From there, the smell drifted into the room. </p>
<h2>The complexity of human aroma</h2>
<p>After five years working with skin bacteria, I am only beginning to fathom the complexity of human aroma. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/289505/original/file-20190826-8868-sxc03q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289505/original/file-20190826-8868-sxc03q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=840&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289505/original/file-20190826-8868-sxc03q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=840&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289505/original/file-20190826-8868-sxc03q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=840&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289505/original/file-20190826-8868-sxc03q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1056&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289505/original/file-20190826-8868-sxc03q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1056&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289505/original/file-20190826-8868-sxc03q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1056&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sweat-stained T-shirt in the ‘Labor’ exhibit.</span>
<span class="attribution"><a class="source" href="https://www.paulvanouse.com/labor.html">Tullis Johnson</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>For instance, while three main strains of bacteria may be responsible for the most common smells of sweat, it would be simplistic to imagine this is the end of the story. Many bacteria have a variety of metabolic options to thrive, and each produces different byproducts and chemical compounds. Some stink, some don’t. How do they interact together and with other bacteria or fungi on the skin to produce our distinct smell? </p>
<p>It has been said that deep human attraction is often <a href="https://www.psychologytoday.com/us/articles/200801/scents-and-sensibility">premised on our scents</a>. If bacteria are responsible for our scent, then are we attracted to a person or their bacteria? Perhaps bacteria help steer human sexual selection and evolution.</p>
<p>[ <em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/119447/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul Vanouse has previously received funding from several government-funded and foundation sources, including NEA, NYSCA, Rockefeller Foundation and Creative Capital Foundation.</span></em></p>What is the smell of sweat? An artist recreates the pungent body odor as an art installation.Paul Vanouse, Professor of Art, University at BuffaloLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1201472019-07-10T21:23:25Z2019-07-10T21:23:25ZHow to exercise in the summer without heat exhaustion<figure><img src="https://images.theconversation.com/files/283408/original/file-20190709-44487-zuosr4.jpg?ixlib=rb-1.1.0&rect=126%2C387%2C5754%2C3476&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Exercising in hot weather adds stress to the body and comes with risk of heat exhaustion.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>With a kilometre to go, <a href="https://olympics.nbcsports.com/2019/07/01/sarah-true-ironman-collapse/">triathlete Sarah True was pulled from the 2019 Ironman European Championship</a> in Frankfurt, Germany, due to heat exhaustion. She was in the lead by seven minutes after having swum, biked and run nearly 225 kilometres. The temperature was 38C.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/HLkREtZARQE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>With summer comes longer days and sunnier skies. It’s an opportunity to shed our winter clothes and get outside to go for a run, get on a bike or play pick-up sports with friends. Indeed, <a href="https://doi.org/10.1093/aje/153.2.172">summer is when we are most active</a>.</p>
<p>The other thing that comes with summer is heat and humidity. As Europe and North America grapple with <a href="https://techcrunch.com/2019/07/05/heat-waves-bring-record-breaking-temperatures-on-a-geological-scale/">recurring summer heatwaves</a>, we all need to take care when being active in the summer heat.</p>
<h2>The work of sweat and blood</h2>
<p>When we exercise, our body’s core temperature increases. To combat this, we have a number of built-in cooling methods. <a href="https://doi.org/10.1152/advan.00126.2014">The main way our body cools itself is through the evaporation of sweat on our skin</a>. For sweat to evaporate it needs to absorb heat. That absorption of heat cools us down.</p>
<p>In addition to sweat, blood is diverted to our skin’s surface to cool and recirculate throughout our body. It’s the reason why many of us become flushed in the face when we’re active. </p>
<p>How much each of these two methods contributes to cooling can vary from person to person. Some people are profuse sweaters while others turn red and hardly sweat at all.</p>
<p>The effectiveness of our body’s cooling also depends on the ambient conditions. The drier the conditions, the more effective sweat is at cooling us. But in high humidity, the air is saturated with water vapour causing our sweat to drip ineffectively off our body. In these situations, our body continues to produce more sweat in the hopes of cooling off.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1145544356914499586"}"></div></p>
<p>Exercising in hot weather adds stress to our body. Diverting blood to our skin to cool means less blood (and oxygen) going to the working muscles. </p>
<p>Sweating also reduces the amount of water in our body and if this lost fluid is not replenished, blood volume goes down. This can lead to lower blood pressure and increased heart rate. At the very least, this results in a decrease in performance. At the extreme end, it can lead to heat exhaustion and heat stroke as happened to Sarah True. </p>
<p>Symptoms can include <a href="https://www.mayoclinic.org/diseases-conditions/heat-exhaustion/symptoms-causes/syc-20373250">exhaustion, fatigue, poor mental functioning (dizziness, confusion, irritability), nausea, vomiting and fainting</a>. If severe heat exhaustion isn’t treated, it can lead to <a href="https://newsinhealth.nih.gov/2013/07/stay-cool">long-term disability and even death</a>.</p>
<h2>Young and elderly at greatest risk</h2>
<p>Even though education and awareness has increased over the years, <a href="https://dx.doi.org/10.1007%2Fs12178-014-9240-0">the prevalence of heat exhaustion may be on the rise</a>. And with record high temperatures being broken year after year due to climate change, the environmental exposure and risk may continue to increase.</p>
<p>Those at the greatest risk are the very young, the elderly and those with pre-existing medical conditions. During Québec’s heatwave in 2018, an <a href="https://www.npr.org/2018/07/10/627687639/estimated-70-deaths-linked-to-canadas-heat-wave">estimated 70 deaths were attributed to the heat</a>. Most of the deaths were in these high risk groups.</p>
<p>In addition, outdoor sports that involve wearing or carrying heavy equipment such as <a href="https://doi.org/10.4085/1062-6050-504-17">football pose an increased risk</a>. This is due to both the weight of the equipment and the layering which prevents sweat from evaporating.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/283407/original/file-20190709-44487-11w6a0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/283407/original/file-20190709-44487-11w6a0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=396&fit=crop&dpr=1 600w, https://images.theconversation.com/files/283407/original/file-20190709-44487-11w6a0p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=396&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/283407/original/file-20190709-44487-11w6a0p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=396&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/283407/original/file-20190709-44487-11w6a0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=497&fit=crop&dpr=1 754w, https://images.theconversation.com/files/283407/original/file-20190709-44487-11w6a0p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=497&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/283407/original/file-20190709-44487-11w6a0p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=497&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Kids cool off in water fountains to beat the heat during the heatwave in Montréal, July 2018.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Graham Hughes</span></span>
</figcaption>
</figure>
<h2>Six tips to avoid heat exhaustion</h2>
<p>When temperatures rise, a few simple precautions can help mitigate the risk:</p>
<ol>
<li><p>Know the weather conditions beforehand.</p></li>
<li><p>Wear sunscreen and light clothing.</p></li>
<li><p>Drink fluids regularly. </p></li>
<li><p>Avoid exercising at peak hours of heat, or exercise in an air-conditioned gym.</p></li>
<li><p>If you’re travelling to a warmer climate, whether in the summer or winter, allow your body to get acclimatized by slowly increasing your activity. </p></li>
<li><p>If you are completing an athletic event during the day and you usually train during the early morning or evening, you should also acclimatize your body to the midday heat.</p></li>
</ol>
<p><em>Scott Lear writes the weekly blog <a href="https://drscottlear.com/">Feeling Healthy with Dr. Scott Lear</a>.</em></p><img src="https://counter.theconversation.com/content/120147/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Scott Lear receives funding from the Canadian Institutes of Health Research, the Heart and Stroke Foundation, Novo Nordisk, Hamilton Health Sciences and the Robert Wood Johnson Foundation.</span></em></p>You can stay fit during soaring summer temperatures — if you follow some simple precautions.Scott Lear, Professor of Health Sciences, Simon Fraser UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1139452019-04-12T09:45:11Z2019-04-12T09:45:11ZHyperhidrosis: the excessive sweating condition that could ruin your life<figure><img src="https://images.theconversation.com/files/268579/original/file-20190410-2931-1akbpcw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/man-hyperhidrosis-sweating-very-badly-under-767078806?src=h1QK-SSyyTvRqKN8eUTuIQ-1-14">Koldunova Anna/Shutterstock.com</a></span></figcaption></figure><p>Most people sweat when they exercise or the weather is hot. But some people sweat far more than this. Hyperhidrosis – excessive sweating – can be a devastating condition that has a huge impact on quality of life, and even prevent those who have it from carrying out everyday tasks. For some it has affected their relationships. Others are so embarrassed by their sweating that they feel unable to leave their house.</p>
<p>Sweating is a normal physiological process that helps the body to regulate its temperature. When we get too hot or exercise, sweat evaporates from the skin and has a cooling effect. People often also notice they sweat when they are anxious or are in a situation that makes them nervous. But for the roughly 3% of people who have <a href="http://www.bad.org.uk/shared/get-file.ashx?id=93&itemtype=document">hyperhidrosis</a>, sweating can be almost constant.</p>
<p>The most common areas of the body affected by hyperhidrosis are hands, feet, underarms, face, and head, although other areas can be affected too. Some people with hyperhidrosis sweat all over, rather than in just some parts of the body. People with hyperhidrosis often sweat in situations where other people don’t, for example, when the weather is cold. </p>
<p>It is not known what causes hyperhidrosis, although it is thought that the nerves that usually make us sweat become over-active. Hyperhidrosis often starts in childhood or adolescence, but can start at any time during life. There is probably a genetic element as well, as there is often a family history in people who have excessive sweating of the hands.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/268582/original/file-20190410-2924-zpb3nz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/268582/original/file-20190410-2924-zpb3nz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/268582/original/file-20190410-2924-zpb3nz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/268582/original/file-20190410-2924-zpb3nz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/268582/original/file-20190410-2924-zpb3nz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/268582/original/file-20190410-2924-zpb3nz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/268582/original/file-20190410-2924-zpb3nz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hyperhidrosis.</span>
<span class="attribution"><span class="source">Werayuth Tes/Shutterstock.com</span></span>
</figcaption>
</figure>
<h2>Few answers</h2>
<p>Without a clear understanding of what causes hyperhidrosis, it is more challenging to find effective treatments. That is why colleagues and I have been <a href="https://www.dmu.ac.uk/about-dmu/news/2018/january/dmu-begins-research-into-debilitating-condition-that-causes-excessive-sweating.aspx">researching the condition</a>. We asked people with hyperhidrosis and healthcare professionals who treat them what questions they would like research to answer. We had 268 people come forward to suggest nearly 600 research questions.</p>
<p>We found that hyperhidrosis has a wide range of severity. At the mild end of the spectrum, the effects may be minimal – a small inconvenience or minor embarrassment. But as severity increases, the impact on quality of life becomes much more substantial. And the condition can have a huge impact on quality of life, affecting people’s career choices and leading to social isolation. For example, some people have such sweaty hands that it makes it difficult to hold a pen or use a keyboard.</p>
<p>People with hyperhidrosis often have anxiety in work situations such as job interviews or meetings where they might be expected to shake hands. Their social life can also be affected, with many people feeling embarrassed by their sweating, and some people have avoided forming intimate relationships due to this. Some people have to change their clothes several times.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/268580/original/file-20190410-2909-mo5yt3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/268580/original/file-20190410-2909-mo5yt3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/268580/original/file-20190410-2909-mo5yt3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/268580/original/file-20190410-2909-mo5yt3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/268580/original/file-20190410-2909-mo5yt3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/268580/original/file-20190410-2909-mo5yt3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/268580/original/file-20190410-2909-mo5yt3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hyperhidrosis: a nightmare in business.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hyperhidrosis-wet-hand-sweat-syndrome-695565307?src=nwfeUFec8kiGYeTSdnthGg-1-0">Quality Stock Arts/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>Many people with hyperhidrosis don’t seek medical help due to the stigma of the condition. They may not even know it is a medical condition at all. Those that do often report difficulties in being taken seriously, lack of access to specialists, and treatment being considered a <a href="https://www.cambridgeshireandpeterboroughccg.nhs.uk/EasySiteWeb/GatewayLink.aspx?alId=9620">low priority</a>.</p>
<h2>Available treatment</h2>
<p>There are a <a href="https://hyperhidrosisuk.org/treatment-options/">number of treatments</a> available for hyperhidrosis, which depend upon the area of the body affected. Temporary treatments include:</p>
<ul>
<li>Strong anti-perspirants containing aluminium chloride </li>
<li>Iontophoresis, where the affected areas are placed in water and a low voltage electrical current passed through it</li>
<li>Botox, which works by blocking a chemical at the nerve endings, so it can’t activate the sweat glands</li>
<li>Oral medications, called anti-cholinergics, which also work by blocking the nerve endings, throughout the body</li>
</ul>
<p>But these are all temporary, and do not work for everyone. The anti-perspirants can cause skin irritation, and oral medication blocks nerve endings throughout the body, so can cause side effects such as a dry mouth and problems urinating. Botox and iontophoresis, meanwhile, need to be repeated regularly and can be expensive.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/268583/original/file-20190410-2898-1ogjs5n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/268583/original/file-20190410-2898-1ogjs5n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/268583/original/file-20190410-2898-1ogjs5n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/268583/original/file-20190410-2898-1ogjs5n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/268583/original/file-20190410-2898-1ogjs5n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/268583/original/file-20190410-2898-1ogjs5n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/268583/original/file-20190410-2898-1ogjs5n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The sweating can be constant, and occur in unusual places on the body.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-shot-african-black-womans-sweaty-1098119765?src=vj79qcWWls6TxR4fO82wUA-2-45">Red Confidential/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>There are also some more permanent solutions available. Some sufferers have had surgery to remove or destroy sweat glands in a localised area (such as the armpits) or endoscopic thoracic sympathectomy (ETS), where the nerves that control sweating are cut. ETS is effective in reducing the sweating of the areas intended, but can lead to very serious side effects such as damage to nerves or organs. Most patients end up with some level of sweating in other areas (<a href="https://www.ncbi.nlm.nih.gov/pubmed/15276490">compensatory sweating</a>) and this can be worse than the original problem, so this surgery is generally only used as a last resort. A newer <a href="https://hyperhidrosisuk.org/treatment-options/miradry/">permanent treatment</a> uses electromagnetic energy to destroy sweat glands.</p>
<p>Despite being a common skin condition, hyperhidrosis is not widely known about, and research is very poorly funded. Raising awareness is key if people are to feel comfortable enough to come forward to ask for help and advice.</p><img src="https://counter.theconversation.com/content/113945/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Louise Dunford receives funding from The UK Dermatology Clinical Trials Network. </span></em></p>For the roughly 3% of people who have this condition, sweating can be almost constant.Louise Dunford, Director of the Institute of Allied Health Sciences Research, De Montfort UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/858312018-03-19T04:30:57Z2018-03-19T04:30:57ZCurious Kids: What happens in the body when we sweat?<figure><img src="https://images.theconversation.com/files/193519/original/file-20171107-1046-h39fxt.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">When we get hot, sensors in the body tell the brain. The brain then tells the sweat glands to work, and we sweat.</span> <span class="attribution"><span class="source">Marcella Cheng/NY-CC-BD</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><em>This is an article from <a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a>, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!</em> </p>
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<p><strong>What exactly happens in the body when we sweat? – Bianca, age 9, Sydney</strong></p>
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<p>Hi Bianca, thank you for your question. </p>
<p>Sweat comes from special parts in our skin called glands. You might be able to see them if you have a very strong magnifying glass. </p>
<p>Try to find lines on your skin, and look where those lines meet. There you will find a sweat gland – we are born with about 2 million of them.</p>
<p>When we get hot, sensors in the body tell the brain. The brain then tells the sweat glands to work, and we sweat. That sweat is salty as it comes from the salty fluid found inside our bodies. We are 60-80% water. If that sweat can evaporate, we will cool down. This is why humans sweat. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/193520/original/file-20171107-1027-1lnufir.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/193520/original/file-20171107-1027-1lnufir.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/193520/original/file-20171107-1027-1lnufir.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1233&fit=crop&dpr=1 600w, https://images.theconversation.com/files/193520/original/file-20171107-1027-1lnufir.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1233&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/193520/original/file-20171107-1027-1lnufir.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1233&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/193520/original/file-20171107-1027-1lnufir.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1550&fit=crop&dpr=1 754w, https://images.theconversation.com/files/193520/original/file-20171107-1027-1lnufir.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1550&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/193520/original/file-20171107-1027-1lnufir.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1550&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Because dogs and cats do not sweat like humans, panting and fur licking helps them to stay cool.</span>
<span class="attribution"><span class="source">Marcella Cheng/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>Do you have a dog, Bianca? I bet you know what dogs do when they get hot; they pant. They take many small breaths and hang their tongues out. Gross! When they pant, water drops fall onto their fur. When those drops evaporate, they cool down. We often see cats licking their fur. Because dogs and cats do not sweat like humans, panting and fur licking helps them to stay cool. Cats always think they are cool.</p>
<p>All healthy humans sweat. We do this for two reasons: either because we are hot and need to cool down, or because we are stressed. </p>
<h2>How does sweat cool us down?</h2>
<p>Think about water, ice and steam. Did you know they are all just water? </p>
<p>Water looks different depending on its temperature. Ice is frozen or solid water. Steam is heated water that has turned into a gas called water vapour.</p>
<p>Try this experiment: lick the back of your hand and then gently blow air over the wet skin. What do you notice? It feels cool, right? </p>
<p>Blowing on your skin makes the water turn into water vapour. The word we use when this happens is “evaporation”. Evaporation helps take away heat.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-how-do-we-get-allergic-to-food-82503">Curious Kids: How do we get allergic to food?</a>
</strong>
</em>
</p>
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<h2>Why else do we sweat?</h2>
<p>So what about that other type of sweating I told you about?</p>
<p>Do you get nervous when you have to speak about something in front of your class at school? </p>
<p>In my job, I have to speak to other scientists at special meetings called conferences. I get nervous about that. Sometimes, I get so nervous that I get sweaty. </p>
<p>Some people get sweaty hands, some get sweaty under their arms and some just sweat all over. I am in the last group. We call this nervous sweating. </p>
<p>Sweating can also happen during an exam or when we are concentrating hard on something important. We don’t know much about this type of sweat, but we do know that it comes from the same sweat glands.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/193522/original/file-20171107-1014-3kzanu.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/193522/original/file-20171107-1014-3kzanu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/193522/original/file-20171107-1014-3kzanu.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=422&fit=crop&dpr=1 600w, https://images.theconversation.com/files/193522/original/file-20171107-1014-3kzanu.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=422&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/193522/original/file-20171107-1014-3kzanu.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=422&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/193522/original/file-20171107-1014-3kzanu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=531&fit=crop&dpr=1 754w, https://images.theconversation.com/files/193522/original/file-20171107-1014-3kzanu.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=531&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/193522/original/file-20171107-1014-3kzanu.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=531&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Sometimes, we get so nervous that we get sweaty.</span>
<span class="attribution"><span class="source">Marcella Cheng/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>Thank you again for your question Bianca, and I hope my answer is helpful.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mondays-medical-myth-you-lose-most-heat-through-your-head-10834">Monday's medical myth: you lose most heat through your head</a>
</strong>
</em>
</p>
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<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. You can:</em></p>
<p><em>* Email your question to curiouskids@theconversation.edu.au
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<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p><em>Please tell us your name, age and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/85831/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nigel Taylor receives, or has received, funding from Defence Science & Technology, Fire & Rescue NSW, the Australian Research Council, the National Health & Medical Research Council, the National Roads and Motorists’ Association and Coal Services Health and Safety Trust.</span></em></p>Sweat comes from special parts in our skin called glands. You might be able to see them if you have a very strong magnifying glass.Nigel Taylor, Associate Professor of Thermal Physiology, University of WollongongLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/897712018-01-12T03:39:37Z2018-01-12T03:39:37ZExtreme heat in sport: why using a fixed temperature cut-off isn’t as simple as it seems<p>Record-breaking temperatures during the Ashes cricket test match in Sydney on Sunday led many to wonder: how hot is too hot to continue playing sport safely? </p>
<p>Exertion-related heat illnesses are a very real concern, even for professional athletes in peak condition. In extreme cases, the heat can be deadly; Rugby League international Kato Ottio <a href="http://www.bbc.com/sport/rugby-league/42633548">died this week</a> after suffering complications from severe heat stroke following training.</p>
<p>While fatal cases of heat illness in sport are mercifully rare, a milder form, heat exhaustion – characterised by nausea, vomiting, and fainting/light-headedness – are much more common in many summer sports. </p>
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<p><em><strong>Read more – <a href="https://theconversation.com/health-check-how-to-exercise-safely-in-the-heat-37286">Health Check: how to exercise safely in the heat</a></strong></em> </p>
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<p>Some commentators <a href="http://www.news.com.au/sport/cricket/the-ashes/england-skipper-joe-root-hospitalised-with-severe-dehydration/news-story/f153f66ab6d4fb631184b1ee4b79c41c">have recommended</a> that play should be suspended when the mercury reaches a particular temperature, such as 41°C. </p>
<p>However, there are several factors that must be collectively considered when predicting heat stress risk of an athlete.</p>
<p>The “temperature” that most people are familiar with through weather forecasts is actually measured in the shade. But physiological strain (rise in heart rate, sweating, body temperature) is very different depending on whether an athlete is directly in the sun or not. </p>
<p>Black globe temperature, which is used to help measure the heat absorbed from the sun, can be as much as 12 to 15°C higher. In fact, our own measurements at the Sydney Cricket Ground on Sunday reached a peak value of <a href="https://twitter.com/ollie_jay13/status/949906353794904064">57.6°C</a> when the air temperature was 41.9°C.</p>
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<h2>What happens to sweat</h2>
<p>Humidity (the amount of moisture held in the air) directly impacts the effectiveness of the most important physiological mechanism that humans have for keeping cool in the heat – sweating. After all, it is the <a href="http://www.physiology.org/doi/abs/10.1152/jappl.1972.32.4.456">evaporation</a>, not the production, of sweat that allows the body to shed excess heat. </p>
<p>Evaporative drive becomes much lower with increasing humidity. This results in sweat either pooling or dripping off the skin, which contributes to dehydration without cooling the body. </p>
<p>In less humid but often hotter conditions, sweat freely evaporates from the skin, releasing large amounts of heat. But body water stores still deplete if they aren’t replaced. </p>
<p>Importantly, sweat evaporation is determined by “absolute” humidity. Yet “relative” humidity – the percentage of the total water-carrying capacity of air that is filled with water vapour – is most commonly reported. </p>
<p>Because the <a href="https://commons.wikimedia.org/wiki/File:PsychrometricChart-SeaLevel-SI.jpg">capacity of air to carry water vapour increases exponentially with air temperature</a>, absolute humidity can be high despite a seemingly low relative humidity (RH) during the hottest time of the day. For example, absolute humidity is higher at 45°C with 25% relative humidity than at 30°C with 50% relative humidity.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/electric-fans-may-not-help-the-elderly-in-a-heatwave-64834">Electric fans may not help the elderly in a heatwave</a>
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<p>Many people who have experienced heat with high humidity are familiar with the sweet relief of even the lightest breeze. This is because wind also promotes evaporation; it helps replace air directly above the skin that is saturated with water vapour with drier air. </p>
<p>The heat loss capacity of an athlete in hot or humid conditions is therefore oppressively low when it is still, but much higher when there is some wind.</p>
<h2>Not all sport is equal</h2>
<p>During exercise, muscle contractions can produce large amounts of heat. However, different sports, and even different positions within a particular sport, result in varying levels of heat production. </p>
<p>Actions requiring vigorous levels of activity that engage large muscle groups (such as running, jumping, squatting, kicking) produce a lot of heat. In contrast, sports with lighter levels of activity (such as standing, walking, light jogging) generate relatively small amounts of heat. </p>
<p>It is probably not surprising that <a href="http://onlinelibrary.wiley.com/doi/10.1002/clc.4960130809/abstract">the heat produced playing cricket</a> is two- to three-times lower than soccer or rugby. However, depending on the format, a cricket match typically lasts much longer.</p>
<p>Some sports require protective equipment that <a href="http://journals.lww.com/acsm-msse/Fulltext/2003/05000/Thermal_Insulation_and_Evaporative_Resistance_of.17.aspx">create a barrier to heat loss</a>, yet can result in a greater heat production to carry or wear them. Sweat rates are typically highest on the <a href="https://link.springer.com/article/10.1007%2Fs00421-010-1744-8">head, back, and shoulders</a>. So wearing a helmet and padding on the upper body probably has the greatest relative impact on the amount of evaporative cooling possible.</p>
<h2>A blanket maximum won’t work</h2>
<p>A simple universal cut-off temperature cannot be applied across all sports because exposure, equipment and activities vary so much. Even within a particular sport, a fixed critical temperature for suspending or modifying play isn’t appropriate as physiological strain can be so different depending on humidity, cloud cover, wind speed. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/its-time-for-australia-to-change-its-attitude-to-extreme-heat-22164">It's time for Australia to change its attitude to extreme heat</a>
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<p>Nevertheless, some sports associations, such as Football New South Wales, have adopted this approach, presumably because it can be easily employed. Other sports organisations, such as Sports Medicine Australia, use combinations of temperature and humidity, but this still does not account for the important effects of the sun and wind. </p>
<p>The Wet Bulb Globe Temperature (WBGT) index, when measured properly, provides a weighted average of the effects of the sun, air temperature, and humidity. Tennis Australia uses a threshold WBGT value of 34°C to recommend the suspension of play. </p>
<p>However, WBGT limits for many sports <a href="http://www.sciencedirect.com/science/article/pii/S1440244007002095">are not well supported by evidence</a>, and <a href="http://www.sciencedirect.com/science/article/pii/S1440244007001478?via%3Dihub">the WBGT index is particularly limited</a> in hot conditions with high humidity or low wind speeds. WBGT values are often inaccurately estimated instead of measured because the required device can be prohibitively expensive.</p>
<p>Accounting for all environmental and sport-related factors to accurately determine the real heat stress risk continues to be a challenge. However, <a href="http://www.bbc.com/sport/cricket/42637298">the needs are clear</a>, and relatively recent technological advances present opportunities to develop modern heat policies that ensure player welfare while preventing unnecessary interruptions of play.</p>
<h2>What athletes can do</h2>
<p>Before suspending play altogether, several strategies can be used to reduce the risk of elevated body temperature, known as hyperthermia. </p>
<p>Placing damp towels containing crushed ice around the neck, or wetting the arms, legs and neck with a damp cloth to promote evaporation are <a href="http://www.jsams.org/article/S1440-2440(17)30443-7/fulltext">more effective</a> in a tennis-related context for <a href="http://journals.lww.com/acsm-msse/Abstract/2017/05000/In_Play_Cooling_Interventions_for_Simulated.16.aspx">both hot/dry and warm/humid</a> conditions. </p>
<p>Such is the power of evaporation, cooling potential is <a href="http://www.tandfonline.com/doi/full/10.1080/23328940.2016.1185206">much greater</a> when pouring water over the body than drinking cold or even iced water.</p><img src="https://counter.theconversation.com/content/89771/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ollie Jay consults to Cricket Australia and National Rugby League. </span></em></p><p class="fine-print"><em><span>Samuel Chalmers receives funding from the Australian Football League. </span></em></p>It seems obvious that a game should be suspended if it’s too hot to play, but it’s not as easy as implementing a maximum temperature.Ollie Jay, Associate Professor, Exercise and Sport Science; Director, Thermal Ergonomics Laboratory, University of SydneySamuel Chalmers, Postdoctoral Fellow in Sport Physiology and Performance, Western Sydney UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/739032017-03-08T19:22:43Z2017-03-08T19:22:43ZHealth Check: do men really sweat more than women?<figure><img src="https://images.theconversation.com/files/159464/original/image-20170306-29005-11d1hkw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sweat creates evaporative cooling for your body, with the amount required determined by your size and shape, not your gender. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/123031771?src=zVUt0fcwBkXRF77EgvEGPg-2-51&size=huge_jpg">from www.shutterstock.com </a></span></figcaption></figure><p>Men are generally taller than women, but we do not define gender on the basis of stature. Similarly, our <a href="http://onlinelibrary.wiley.com/doi/10.1113/EP086112/full">latest research</a> shows we cannot define men and women according to their propensity to sweat (although some parents and partners might suggest otherwise). </p>
<p>When we studied men and women during exercise in warm, dry conditions, gender differences in heat loss responses (skin blood flow and sweating) could be explained almost entirely by individual variations in body size and shape. </p>
<p>The results refute the common saying “men sweat, while women glow”.</p>
<h2>How objects - and bodies - lose heat</h2>
<p>Heat loss from any object is dictated by the ratio of its surface area to its mass, described by the term “specific surface area”. Hot objects with a larger specific surface area cool more quickly than those with a smaller specific surface area. Doubling the radius (size) of a sphere increases its surface area four-fold but its mass eight-fold: this is known as “isometric growth”. Isometrically larger objects don’t lose heat as easily.</p>
<p>Shape (morphology) also has a powerful influence on heat loss, so a thin rectangular prism loses heat much faster than a sphere of the same composition and mass. In a <a href="https://theconversation.com/mondays-medical-myth-you-lose-most-heat-through-your-head-10834">previous article</a>, we explained you’re no more likely to lose heat from your head than other parts of your body.</p>
<p>Unlike geometric objects, animals do not grow isometrically; we retain a recognisable shape, but our proportions change (this is known as “allometric growth”). This is most evident in children, who have proportionally larger heads and shorter limbs than adults. </p>
<p>However, if you double your weight through building muscle and putting on fat (without changing height), this does not result in a doubling of your skin surface area. Such a weight change increases your surface area <a href="https://www.ncbi.nlm.nih.gov/pubmed/2520314">only by about 30%</a>, which translates into reduced specific surface area, and lower heat loss by these physical mechanisms. The larger a person is, the lower is their specific surface area and the less effective these mechanisms become. This is where the physiological mechanisms of heat loss, particularly sweating, come into play in preventing undesirable heat gains.</p>
<h2>Sweating and evaporative cooling</h2>
<p>Since humans evolved <a href="http://genome.cshlp.org/content/15/8/1161.full">in the heat of Africa</a>, we acquired an ability to transport heat from deep within our bodies to the skin surface for dissipation via skin blood flow. Similarly, we acquired an evaporative cooling mechanism that can function when the air is hotter than the skin: sweating. These physiological responses enable us to manage body heat, and they are activated when physical heat loss becomes insufficient.</p>
<p>To examine the influence of body shape and gender on these two physiological responses to manage body heat, <a href="http://onlinelibrary.wiley.com/doi/10.1113/EP086112/full">we studied</a> men and women (60 university students) of widely variable but overlapping body sizes. Subjects had very similar exercise habits, endurance fitness and amounts of body fat. </p>
<p>For each participant, we calculated a target exercise intensity related directly to their skin surface area. This resulted in comparable increases in body temperature across all participants, and equivalent heat-loss requirements. To the best of our knowledge, this was the first investigation to achieve those outcomes across a morphologically diverse sample of men and women. Previous researchers seem not to have fully appreciated these important experimental design criteria, leading to experiments that perpetuated the myth that all men sweat more than women. </p>
<p>Our analyses have shown that variations in skin blood flow and sweating between men and women are dependent not on gender, but on body morphology.</p>
<p>In answering our questions, we demonstrated that the lyrics of <a href="https://en.wikipedia.org/wiki/Down_Under_(song)">“Down under” (Men at Work)</a> require modification. </p>
<blockquote>
<p>Do you come from a land down under?</p>
<p>Where women glow and men plunder?</p>
</blockquote>
<p>While we do come from a land down under, and while some men may unfortunately still plunder, women do not glow. They sweat just like men, and for the same reason: to lower body temperature. </p>
<h2>Three different types of sweat</h2>
<p>To consider the question of how sweat relates to body odour, we need to go a bit broader. </p>
<p>The ubiquitous sweat glands humans possess for evaporative cooling are known as “eccrine” glands. However, we all have two other types of glands in our skin: <a href="https://www.ncbi.nlm.nih.gov/pubmed/3812728">“apocrine” and “apoeccrine” glands</a>.</p>
<p>While eccrine glands are found distributed throughout the body, apocrine and apoeccrine glands have a limited distribution, predominantly located in regions where adults grow longer - sometimes curlier - hair (regardless of whether we remove that hair). </p>
<p>The apocrine glands are found beside hair follicles, where they secrete a milky, oily fluid. The apoeccrine glands, which appear to develop after puberty, seem to be the dominant gland within the armpits. They secrete a watery fluid like the eccrine glands. </p>
<p>The odour we sometimes detect around sweaty people, or their clothes, comes mostly from secretions of the apocrine and apoeccrine glands. Those secretions are initially odourless, but bacterial action on that fluid leads to smelly men, and smelly women.</p><img src="https://counter.theconversation.com/content/73903/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sean Notley receives, or has received, funding from the University of Ottawa, Human and Environmental Research Unit, the Australian Research Council and the University of Wollongong.</span></em></p><p class="fine-print"><em><span>Nigel Taylor receives, or has received, funding from Defence Science & Technology, Fire & Rescue NSW, the Australian Research Council, the National Health & Medical Research Council, the National Roads and Motorists’ Association and Coal Services Health and Safety Trust. </span></em></p>They say ‘men sweat, while women glow’. But new research shows gender is not the reason for different levels of sweating.Sean Notley, Postdoctoral Fellow, L’Université d’Ottawa/University of OttawaNigel Taylor, Associate Professor of Thermal Physiology, University of WollongongLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/628542016-07-26T12:24:33Z2016-07-26T12:24:33ZDoes drinking hot tea in summer really cool you down?<figure><img src="https://images.theconversation.com/files/131406/original/image-20160721-32610-1rlsu1f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Refreshing – or a sentence to sweat?</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=tea%20summer&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=247474183">Shutterstock</a></span></figcaption></figure><p>I remember as a child, on the rare warm days that we used to get in Britain, my grandmother telling me to “have a cup of black tea … it will help cool you down”. As a seven-year-old, this seemed like a crazy idea, especially when all I wanted was a cold lemonade and another ice cream. But it appears that this old wives’ tale may actually be more Stephen Hawking than Stephen King.</p>
<p>The idea of drinking hot drinks in warm weather goes back hundreds of years. <a href="http://www.bbc.co.uk/news/magazine-27991440">Tea, or “chai” is one of the most popular drinks in India</a>, and many of the <a href="https://en.wikipedia.org/wiki/List_of_countries_by_tea_consumption_per_capita">leading consumers of tea per capita are in tropical or desert regions</a>. Recently, evidence has begun to emerge that drinking hot drinks may really help to <a href="http://www.ncbi.nlm.nih.gov/pubmed/22574769">cool you down</a>, too.</p>
<p>In 2012, <a href="http://sydney.edu.au/health-sciences/about/people/profiles/ollie.jay.php">Ollie Jay</a> published the <a href="http://www.ncbi.nlm.nih.gov/pubmed/22574769">first of a series</a> of papers to see if drinking a warm drink can actually lower the amount of heat stored by the body compared to a cold drink. In this first study, volunteers were asked to cycle at a relatively low intensity for 75 minutes in around 24°C heat, 23% relative humidity, while consuming water at either 1.5˚C, 10˚C, 37˚C or 50˚C. </p>
<p>The change in core temperature was slightly greater when 50˚C water was ingested compared to 1.5˚C and 10˚C water. However, when the authors considered the effect of drink temperature on body heat storage, which is a better indicator of total body temperature, the results were very different. Following the ingestion of the warm drink, overall body heat storage was actually lower following exercise than with cooler drinks. </p>
<h2>The sweat factor</h2>
<p>An explanation for these findings appears to be related to how sweating may be influenced by drink temperature. Sweating, and more importantly the evaporation of this sweat, is one of the <a href="https://theconversation.com/from-perspiration-to-world-domination-the-extraordinary-science-of-sweat-62753">key avenues for modulating body temperature and maintaining heat balance</a>. </p>
<p>Due to the increased heat load from drinking a warm drink, there is a compensatory increase in overall sweat output, which outweighs the internal heat gain from the warm drink. Consistently, a 50˚C drink results in a higher whole body sweat loss (around 570ml vs about 465ml for 1.5˚C). In practical terms, this means that more sweat is produced which is evaporated from the skin surface, increasing heat loss from evaporation and reducing body heat storage. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Cold water: should he drink it?</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=runner%20hot&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=154131425">Shutterstock</a></span>
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</figure>
<p>Importantly, however, this study was conducted under conditions that allowed complete evaporation of sweat – in other words dripping sweat was limited by maintaining a good airflow and keeping humidity low. The results would likely be different in conditions where sweat evaporation is limited, such as in hot and humid conditions. In fact, drinking cold drinks may be more favourable in these circumstances, minimising inefficient sweat losses – dripping sweat – and consequently aiding an individual’s hydration status. </p>
<h2>Mouth or stomach?</h2>
<p><a href="http://www.ncbi.nlm.nih.gov/pubmed/24577060">In a second study</a>, Jay aimed to establish the effect of drink temperature on local sweat rate, and to determine the location of thermoreceptors that may influence sweating. They demonstrated that with differing drink temperatures, colder drinks (1.5˚C) resulted in reductions in local sweat rate compared to when warm drinks were ingested (50˚C), despite identical changes in core and skin temperature.</p>
<p>Interestingly, however, differences in the sweat response were found when fluid was either swilled around the mouth or delivered directly to the stomach via a nasogastric tube. The data showed that only when cold drinks were delivered directly to the stomach did they result in reduced local sweat rate. This data indicates that the sensors responsible for influencing the sweat response, and therefore regulation of body temperature, reside somewhere in the abdominal cavity. </p>
<p>In a <a href="http://www.ncbi.nlm.nih.gov/pubmed/?term=Ice+Slurry+Ingestion+Leads+to+a+Lower+Net+Heat+Loss+during+Exercise">third study conducted in their lab</a>, the team asked people to consume either 37˚C fluid or ice during exercise. In agreement with their previous work, they showed that there was a reduction in heat loss following ice ingestion compared to fluid at 37˚C, as a result of reduced sweat evaporation from the skin surface. </p>
<p>This has implications for endurance performance in the heat. In essence, where changes in body temperature are known to <a href="http://www.ncbi.nlm.nih.gov/pubmed/10066720">influence performance, ice ingestion</a> could result in an increase in body heat, negatively influencing endurance capability. The ingestion of an iced drink prior to exercise and in hot and humid environments, however, should be beneficial. </p>
<p>So, depending on your environmental conditions, maybe reaching for that cup of tea isn’t such a crazy idea after all. Plus the moral of the story: listen to your grandmother’s advice – it’s based on years of experience.</p><img src="https://counter.theconversation.com/content/62854/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Here’s the science.Steve Faulkner, Research associate, Loughborough UniversityKaty Griggs, Research Assistant and PhD student, Loughborough UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/627532016-07-19T17:48:35Z2016-07-19T17:48:35ZFrom perspiration to world domination – the extraordinary science of sweat<figure><img src="https://images.theconversation.com/files/131129/original/image-20160719-7903-1ozfw05.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Per litre of sweat produced, we can dump around half a million calories of heat from our bodies.
</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&search_tracking_id=g9Sz3_xPH9hMxsIgn6_t8g&searchterm=sweating%20in%20the%20gym&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=428924680">Maridav/Shutterstock</a></span></figcaption></figure><p>I’m writing this on the UK’s hottest day of the year. There is a light breeze, but everyone I have seen today has beads of sweat on their forehead. Seeing someone wiping their brow is a fairly common sight in midsummer, but it reveals a simple and fascinating truth about our species: without sweat, we would not still be here. Without this absolutely amazing technology we would not have climbed our way to the top of the evolutionary pile. Many animals perspire, but no others use it as such an efficient and refined cooling technology. So how does it work and why do we owe it so much?</p>
<p>We often assume that it is our brain power that differentiates us from other animals. It is obvious that we are able to process more intellectual stimuli than other mammals, but any PC owner knows that computational power is completely useless if the cooling system fails. And this is what really sets us apart. It is our ability to maintain an effective working temperature, not just so that we can keep moving, but so that we can keep thinking while in motion, efficiently chasing down the quarry.</p>
<p>As a species, over short distances, we are hopeless runners. We might be able to go a long way but what use is that if we can’t catch anything? The truth is that we never could if it weren’t for several factors that make us identifiably human. And it is our ability to perspire which renders them all effective. So we may have perfect bodies for distance running, but those features that enable us to move so effectively are useless without correct temperature control.</p>
<h2>Two legs are better than four</h2>
<p>There are distinct thermoregulatory advantages to being a two-legged human. Being merely upright, for example, means that less of the sun hits you when it’s at its hottest. The bipedal human exposes only about <a href="http://www.sciencedirect.com/science/article/pii/004724849190002D">7% of their surface area to sunlight; it is triple this for a quadruped</a>. This fact alone means that being on two legs enables you to move with greater heat efficiency. </p>
<p>Also, by being upright, we can take advantage of the fact that our brains are further away from the harsher micro-climate at ground level. It is hotter there because it is heated by the sun and because there is less air movement. And with air movement comes evaporation, which is the real miracle technology. Evaporation is such an effective way to lose heat that if a litre of sweat is able to evaporate on the surface of your skin, you can lose about half a million calories of heat in the process.</p>
<p>While most quadrupeds sweat, they do so to maintain skin health and create scent (we do this, too), and even to create ear wax (<a href="https://www.ncbi.nlm.nih.gov/pubmed/9433684">which, amazingly, is a sort of sweat</a>). But for thermoregulation, most animals use interior air movement (panting) to cool down – where their bodies have to <a href="http://wiki.ggc.usg.edu/wiki/Panting_as_a_thermoregulation_strategy">actively work to lose heat</a>. So that means, on a hot day, we could chase down a quadruped, and when it stopped to shed some heat, we humans could keep going and close the gap a little. Eventually, the distance between predator and prey would close as their technology failed, and ours kept functioning. Sweat meant that <a href="http://www.sciencedirect.com/science/article/pii/004724849190002D">we were much better hunters than we appeared</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/131124/original/image-20160719-8062-yubw4r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/131124/original/image-20160719-8062-yubw4r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/131124/original/image-20160719-8062-yubw4r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/131124/original/image-20160719-8062-yubw4r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/131124/original/image-20160719-8062-yubw4r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/131124/original/image-20160719-8062-yubw4r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/131124/original/image-20160719-8062-yubw4r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In every bead of sweat there is sodium, potassium, calcium, magnesium, zinc, copper, iron, chromium, nickel and lead.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-359436725/stock-photo-forehead-sweat.html?src=FT9LP0i-3_3aACtxOhE7dA-1-0">Chaikom/Shutterstock</a></span>
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</figure>
<h2>Conflicting sweat signals</h2>
<p>It is decidedly odd that sweat is taboo in our society. Do it in the wrong place or from the wrong part of your body and the people around you will become uncomfortable, or at the very least make you feel so … and that will probably make you sweat.</p>
<p>Sweat in a gym and it’s aesthetic: it’s a badge of honour. It’s part of the training montage of any sports movie you might think of. But get it wrong – sweat in a job interview, a presentation, or in a social situation – and people will think you’ve lost control, or that it’s a stress response because you are deceiving them. But without it we would never have become who we are, have survived to the point when we could invent things, create art, make music, or surf the net.</p>
<p>So as you struggle through the next few days of hot weather, think of those beads of sweat on your forehead, and the fact that the exposed skin there, and its ability to perspire, is what keeps your brain functioning in the heat. In the past, it made you a lethal weapon out on the savanna, now it might allow you to reflect on what it has allowed you to achieve in the past, and that without those <a href="http://www.sweathelp.org/home/understanding-hyperhidrosis.html">2.5m sweat glands</a> on your skin working to maintain the correct temperature for thought, you would not be here, reading this.</p><img src="https://counter.theconversation.com/content/62753/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vybarr Cregan-Reid receives funding from Arts Council England. He is the author of 'Footnotes: how running makes us human' published by Ebury.</span></em></p>Our success as a species is 5% inspiration and 95% perspiration.Vybarr Cregan-Reid, Reader in English and Environmental Humanities and Author of Footnotes: How Running Makes us Human (Ebury, 2016), University of KentLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/495682015-11-03T11:08:30Z2015-11-03T11:08:30ZEleven body fluids we couldn’t live without<figure><img src="https://images.theconversation.com/files/99266/original/image-20151022-15414-1nhuve6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Blood is just one of the body fluids we need to survive. </span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-193429070/stock-photo-blood-donor-at-donation-with-a-bouncy-ball-holding-in-hand.html?src=57IVDqZZgssJrc82KtPa8A-1-23">Blood bag via www.shutterstock.com.</a></span></figcaption></figure><p>How is a human being like a fish? </p>
<p>Just as a fish never stops to think about the water in which it spends its entire life, so do many human beings rarely pause to consider the body fluids that make our lives possible. </p>
<p>Though not always fit for polite conversation, even the less pleasant among them play a crucial role in maintaining health. By learning a bit more about 11 of these body fluids, we can develop a deeper appreciation for the beauty and complexity of our own biology. What exactly are these fluids, and what often unheralded contributions do they make?</p>
<h2>1. Bile</h2>
<p>Bile is a brown to dark green fluid that is produced by the liver, stored in the gallbladder (a synonym for bile is gall), and released into the intestines when we eat. It is partly responsible for the color of vomitus and stool. Its most important ingredient is bile salts, which function like soap to break down dietary fats, enabling them and fat-soluble vitamins such as A, D and E to be absorbed. They also help to prevent the cholesterol-containing bile in the gallbladder from forming gallstones.</p>
<p>Curiously, about 15 grams of bile salts are excreted into the intestine each day, yet the human body contains only about five grams in total. How is this possible? The answer is that bile salts are recycled, being reabsorbed into the blood through the small intestine and then secreted again by the liver. </p>
<p>Some intestinal diseases, such as Crohn’s disease, can damage the part of the small bowel where bile salts are reabsorbed, predisposing patients to gallstones.</p>
<h2>2. Blood</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/99263/original/image-20151022-15421-la6k9h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/99263/original/image-20151022-15421-la6k9h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/99263/original/image-20151022-15421-la6k9h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/99263/original/image-20151022-15421-la6k9h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/99263/original/image-20151022-15421-la6k9h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/99263/original/image-20151022-15421-la6k9h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/99263/original/image-20151022-15421-la6k9h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/99263/original/image-20151022-15421-la6k9h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Give a little.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-193429070/stock-photo-blood-donor-at-donation-with-a-bouncy-ball-holding-in-hand.html?src=57IVDqZZgssJrc82KtPa8A-1-23">Blood donation via www.shutterstock.com.</a></span>
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<p>Perhaps the most important body fluid of all is blood. The average adult contains about six liters of blood, which functions to transport oxygen to cells, carry metabolic waste products such as carbon dioxide away from cells and transport infection-fighting white blood cells, glucose, hormones and other essential substances throughout the body. Blood also contains cell fragments called platelets and clotting factors that help to seal leaks that may develop in blood vessels.</p>
<p>An adult’s body contains about 25 trillion red blood cells – about one-third of all the body’s cells. Red blood cells survive on average about 120 days, which means that every second of every day, an adult human produces about two million red blood cells. If lined up end to end, the tiny blood vessels in which gas is actually exchanged, the capillaries, would reach a length of about 60,000 miles, long enough to encircle the earth more than twice.</p>
<h2>3. Menstrual fluid</h2>
<p>The average woman menstruates every 28 days over 42 years of her life, for a total of about 520 menstrual periods. The average volume of menstrual fluid is approximately 40 milliliters, or about 2.5 tablespoons in total. The fluid itself is about one-half blood, and also contains tissue from the inner lining of the uterus, mucus and secretions from the vagina. If the amount of bleeding is abnormally high, it can result in anemia, a deficit of red blood cells.</p>
<p>Along with blood and semen, menstrual fluid is one of the body fluids with the strongest psychological and cultural overtones. Traditionally, the onset of menstruation is associated with the transition from childhood to adulthood, and the onset of each menstrual cycle has long provided the best evidence that a woman is not pregnant. Some societies and faith traditions have sequestered menstruating women, although menstrual fluid is no more biologically hazardous than blood.</p>
<h2>4. Mucus</h2>
<p>Mucus sounds unpleasant, but none of us would be here without it. A slippery, clear liquid produced by mucous glands, it lines the cells of the bronchi in the lungs, the stomach and intestines, the urinary and reproductive tracts, and the eyes and ears. Mucus contains a variety of important substances, including antiseptic enzymes, antibodies and mucins that give mucus its gel-like properties. The average adult produces about one liter of mucus per day.</p>
<p>Mucus keeps the lining of the respiratory system from drying out and also filters out dust and infectious agents in the air we breathe. Microscopic hair-like projections from the cells lining the lung’s air passages help to propel the mucus back up toward the mouth at a speed of about one millimeter per minute, where it can be swallowed or expectorated. </p>
<p>Patients with cystic fibrosis have a genetic mutation that makes their mucus too thick, undermining this important defense against infection.</p>
<h2>5. Pus</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/99253/original/image-20151021-15426-22wldr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/99253/original/image-20151021-15426-22wldr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/99253/original/image-20151021-15426-22wldr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=787&fit=crop&dpr=1 600w, https://images.theconversation.com/files/99253/original/image-20151021-15426-22wldr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=787&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/99253/original/image-20151021-15426-22wldr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=787&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/99253/original/image-20151021-15426-22wldr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=989&fit=crop&dpr=1 754w, https://images.theconversation.com/files/99253/original/image-20151021-15426-22wldr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=989&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/99253/original/image-20151021-15426-22wldr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=989&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Any pus? Watercolour by J. Cats, 1787, after B. Maton.</span>
<span class="attribution"><span class="source">Wellcome Library, London</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Pus sounds even more disagreeable but serves as a sign that the immune system is working. A white, yellow or brown viscous fluid that accumulates at sites of infection, pus usually consists of bacteria, white blood cells, and other proteins and cell debris. Pus under the skin is often found in a pimple, but deeper in the body a larger collection is known as an abscess. Pimples and abscesses represent the body’s attempt to contain the spread of an infection.</p>
<p>For many centuries, one of the dictums of the barber-surgeon was, “Where there is pus, evacuate it,” thereby purging the infection from the body. Until several decades ago, drainage required a surgical procedure. Today, however, many abscesses are drained using just a needle and catheter, with ultrasound or CT imaging for guidance. This less invasive approach reduces the need for anesthesia, recovery time and cost.</p>
<h2>6. Semen</h2>
<p>Semen, the fluid released by males at ejaculation, generally contains spermatozoa, the gametes that fertilize the female egg, though this is not the case for males who have undergone the most common sterilization procedure, vasectomy. </p>
<p>In addition to providing a medium through which sperm can “swim,” semen also contains fructose, a sugar that nourishes the sperm, as well as alkaline secretions that help to neutralize the normally acidic environment of the vagina.</p>
<p>Females are born with all the eggs they will ever have, but males continuously produce gametes from puberty onward, and the average healthy male’s ejaculate of about five milliliters contains approximately 300 million spermatozoa. </p>
<p>Why such large quantities are produced when only one sperm can fertilize an egg is a bit of a puzzle, but one explanation may be that the competition between sperm helps to select for the fittest.</p>
<h2>7. Saliva</h2>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/99269/original/image-20151022-15426-1r7lqcw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/99269/original/image-20151022-15426-1r7lqcw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=750&fit=crop&dpr=1 600w, https://images.theconversation.com/files/99269/original/image-20151022-15426-1r7lqcw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=750&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/99269/original/image-20151022-15426-1r7lqcw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=750&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/99269/original/image-20151022-15426-1r7lqcw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=943&fit=crop&dpr=1 754w, https://images.theconversation.com/files/99269/original/image-20151022-15426-1r7lqcw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=943&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/99269/original/image-20151022-15426-1r7lqcw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=943&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Drool, baby, drool.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-3227780/stock-photo-cute-baby-drooling.html?src=G0E1zC4Cs22yU0iEkGYcTw-1-0">Baby via www.shutterstock.com</a></span>
</figcaption>
</figure>
<p>Saliva is secreted by salivary glands in and around the mouth. The average adult produces about a liter of saliva per day, with peak secretion at meals. Like mucus, saliva contains antibacterial enzymes and antibodies, as well as mucus itself. Saliva helps to moisten food, which is important to lubricate chewing and swallowing. It also enhances taste, because if the chemicals in food were not in a liquid medium, they could not be detected by taste receptors. </p>
<p>Some of the enzymes in saliva also begin to break down substances in food, such as starches, which are broken down by amylase. Because such enzymes are generally neutralized within seconds after reaching the highly acidic secretions in the stomach, they probably function mainly to break down food particles trapped between teeth, helping to prevent cavities. </p>
<p>Patients who lack sufficient saliva have much higher rates of tooth decay and gum disease.</p>
<h2>8. Sweat</h2>
<p>Sweat, like saliva, consists almost entirely of water, though it also contains minerals that account for its salty taste. Sweat production can vary widely between one-tenth of a liter and eight liters per day, and during intense exercise, an adult may produce two liters per hour or more. The body’s three million sweat glands come in two types. Eccrine glands are found all over the body, with the highest density in palms and souls. Apocrine glands are located most prominently in the armpits.</p>
<p>Sweat’s most important role is thermoregulation, helping to cool the body when it begins to overheat. By comparison, dogs, which lack sweat glands, must pant to dissipate heat through evaporation. The brain stimulates sweating through nerves, and the rate is increased in response not just to heat but also emotional states. In contrast to heat-based sweating, the emotional type is associated with perspiration in only the palms, soles and armpits.</p>
<h2>9. Tears</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/99257/original/image-20151021-15414-j4e9eq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/99257/original/image-20151021-15414-j4e9eq.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/99257/original/image-20151021-15414-j4e9eq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=638&fit=crop&dpr=1 600w, https://images.theconversation.com/files/99257/original/image-20151021-15414-j4e9eq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=638&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/99257/original/image-20151021-15414-j4e9eq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=638&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/99257/original/image-20151021-15414-j4e9eq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=801&fit=crop&dpr=1 754w, https://images.theconversation.com/files/99257/original/image-20151021-15414-j4e9eq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=801&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/99257/original/image-20151021-15414-j4e9eq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=801&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Engraving of the lacrimal gland.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Gray896.png">Henry Vandyke Carter, via Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>Tears are produced by the lacrimal glands above and lateral to the eye, and are spread over the eye’s surface by blinking. They are drained into the nasal cavity, which explains why people often get a runny nose when they cry. Tears serve three functions: to lubricate the eye, to remove irritants such as smoke (and a sulfuric acid-producing chemical from cut onions) and in association with emotional states such as sorrow and joy.</p>
<p>Dry eye syndrome, the most common eye disease, affects as many as one-third of elderly people, though it can occur at any time in life. The most common cause is decreased tear production, which in most patients occurs for no known reason, though it is associated with a variety of diseases and medications. The most common treatment involves, naturally enough, the use of eye drops.</p>
<h2>10. Urine</h2>
<p>The average adult produces about 1.5 liters of urine per day. Produced by the kidneys and stored by the bladder, urine contains many substances that must be removed from the body to maintain a state of health. These include the breakdown products of protein metabolism, which would become toxic if they were allowed to accumulate in the blood. Urine also serves as the principal means for removing excess salt and water from the body. </p>
<p>A common diagnostic procedure in medicine is urinalysis. Finding glucose in urine could indicate that a patient is suffering from diabetes mellitus, a disease that got its name in part from the fact that the urine of diabetic patients tastes sweet. Likewise, finding bacteria suggests that the patient is suffering from a urinary tract infection. Interestingly, most of the amniotic fluid that cushions a fetus in utero is made up of urine produced by the fetus’ kidneys.</p>
<h2>11. Vomitus</h2>
<p>Vomitus differs from the other body fluids discussed here because it is not produced under everyday circumstances. Everyone vomits at some point in their life in response to one of several types of stimuli. The balance center of the inner ear can induce vomiting, as in motion sickness. Another cause is irritation of the gastrointestinal tract by infections and poisons.</p>
<p>In some cases, vomiting purges the body of toxins, but in other cases vomitus contains only food. In either case, the fluid is usually highly acidic, because of the acids normally secreted by the stomach. In individuals who vomit frequently, such as patients with bulimia, this acid can erode the surface of the teeth and cause dangerous changes in the pH balance of the blood. The presence of blood in vomitus is generally a sign of bleeding from the esophagus or stomach.</p>
<p>This list of bodily fluids only scratches the surface. For every fluid that is regularly visible to the eye, there is another that, at least in health, we see only rarely. These include amniotic fluid, cerebrospinal fluid and the fluids that lubricate the surface of the heart and lungs, the abdominal organs and the joints, among many others. To get to know these fluids better is to gain deep insights into the biology of the human body in both health and disease.</p><img src="https://counter.theconversation.com/content/49568/count.gif" alt="The Conversation" width="1" height="1" />
By learning a bit more about these body fluids, we can develop a deeper appreciation for the beauty and complexity of our own biology.Richard Gunderman, Chancellor's Professor of Medicine, Liberal Arts, and Philanthropy, Indiana UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/220602014-11-30T18:55:15Z2014-11-30T18:55:15ZExplainer: why do I sweat so much and how can I stop it?<figure><img src="https://images.theconversation.com/files/46653/original/gj9s6b6r-1397715491.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hyperhidrosis or excessive sweating affects around 3% of the population.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/aheram/2718432939">Jayel Aheram</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Everybody sweats, some more than others. It’s a physiological reaction to heat and the body’s mechanism to regulate core temperate. </p>
<p>Individual sweat rates vary and are influenced by factors such as ambient temperature, humidity, air movement, exercise intensity, clothing and body size. Daily fluid loss from sweat may be as little as 100ml per day for a sedentary person in a cool climate or as much as nine litres per day for elite athletes training in hot and humid climates. </p>
<p>The body has two main types of sweat glands. Eccrine glands are found all over the body. These are supplied by sympathetic nerves and activated in response to heat and stress. Apocrine glands are found mainly in the armpits and groin and contribute to body odour rather than moisture. </p>
<p>Body odour is produced when bacteria break down the protein secreted in apocrine sweat. High salt levels in the eccrine gland sweat inhibit bacterial growth, making eccrine sweat odourless.</p>
<p>The human <a href="http://www.health.harvard.edu/newsletters/Harvard_Mental_Health_Letter/2011/March/understanding-the-stress-response">stress response</a>, also known as the fight-or-flight response, involves secretion of adrenaline by the adrenal gland. The adrenaline released travels in the circulation to the skin and activates eccrine sweating. Many people are familiar with the sensation of sweaty palms at moments of stress or anxiety.</p>
<h2>Deodorants</h2>
<p>Roll-on and spray antiperspirants are sufficient for all but the most severe sweaters. The main ingredients, aluminium chloride and aluminium chlorohydrate, have stood the test of time as a <a href="http://www.ncbi.nlm.nih.gov/pubmed/16045991">safe</a> and effective way to control underarm perspiration. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/64195/original/ryzwv82x-1415675051.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/64195/original/ryzwv82x-1415675051.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/64195/original/ryzwv82x-1415675051.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=814&fit=crop&dpr=1 600w, https://images.theconversation.com/files/64195/original/ryzwv82x-1415675051.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=814&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/64195/original/ryzwv82x-1415675051.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=814&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/64195/original/ryzwv82x-1415675051.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1023&fit=crop&dpr=1 754w, https://images.theconversation.com/files/64195/original/ryzwv82x-1415675051.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1023&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/64195/original/ryzwv82x-1415675051.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1023&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ban Roll-on Deodorant magazine advertisement from 1957.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/29069717@N02/11483232083">Classic Film/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
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</figure>
<p>Antiperspirants can be used anywhere on the body. The aluminium reacts with the electrolytes in the sweat to form a gel plug that blocks the sweat duct. This blockage feeds back to the sweat gland and inhibits sweat secretion. </p>
<p>The first commercial deodorant, <a href="http://www.mum-deo.com/about-mum/history/">Mum</a>, was developed and patented by a US inventor in 1888. </p>
<p>Bristol Myers bought the company in 1932 and in the late 1940s developed a roll-on applicator based on the newly invented ball-point pen. In 1952, the company began marketing the product under the name Ban Roll-On in the United States. It is still sold under the name Mum in the United Kingdom and Australia.</p>
<p>Long-acting high-intensity preparations containing <a href="http://www.racgp.org.au/afp/2013/may/hyperhidrosis-and-bromhidrosis/">aluminium chloride hexahydrate</a> have become increasingly available in recent years and many heavy sweaters can gain control with these agents. Some products are sold in pharmacies over the counter, without the need for a prescription.</p>
<h2>Hyperhidrosis</h2>
<p><a href="http://www.racgp.org.au/afp/2013/may/hyperhidrosis-and-bromhidrosis/">Approximately 3%</a> of the population suffer from some form of excessive sweating, called hyperhidrosis. About half of those affected have axillary (or underarm) hyperhidrosis. </p>
<p>If over-the-counter products don’t give you relief, it might be time to visit a specialist. In the assessment, the dermatologist will take a history to establish the nature and severity of the sweating and the impact it is having on your life. </p>
<p>The specialist will examine the skin for irritation or a rash. They will also take blood tests to exclude conditions such as thyroid disease and diabetes, which can sometimes cause excessive sweating. Some antidepressants can also make sweating worse. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/64192/original/599fg4p8-1415674593.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/64192/original/599fg4p8-1415674593.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/64192/original/599fg4p8-1415674593.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/64192/original/599fg4p8-1415674593.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/64192/original/599fg4p8-1415674593.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/64192/original/599fg4p8-1415674593.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/64192/original/599fg4p8-1415674593.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Thyroid disease, diabetes and some antidepressants can cause excessive sweating.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/modenadude/3517954234">Asim Bharwani/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
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</figure>
<p>If you have hyperhidrosis, or excessive eccrine sweating, the dermatologists <a href="http://www.racgp.org.au/afp/2013/may/hyperhidrosis-and-bromhidrosis/">may prescribe</a> tablets to reduce the nerve activation of sweat glands. Or they may recommend <a href="http://www.racgp.org.au/afp/2013/may/hyperhidrosis-and-bromhidrosis/">iontophoresis treatment</a>, which uses water and a mild electrical current to deal with sweaty palms and soles.</p>
<p>Another option is to use Botox to paralyse the eccrine glands and stop the sweating dead. Botox is listed on the Medicare Benefits Schedule for underarm sweating in those who have tried everything else without success. </p>
<p>Botox is injected into the skin of the armpit superficially. While the injections are moderately uncomfortable, no local anaesthesia is required. The armpits will then remain completely dry for somewhere between six and nine months. </p>
<p>Botox can also be used for sweating elsewhere on the body, but without the Medicare rebate. The cost can be close to A$1,000, depending on the size of the area to be treated and the amount of Botox required.</p>
<p>Hyperhidrosis was traditionally treated with <a href="http://www.hopkinsmedicine.org/healthlibrary/test_procedures/neurological/sympathectomy_135,25/">sympathectomy surgery</a>, which involves cutting the nerves that trigger sweating, but this is becoming a thing of the past. While some people get good results, compensatory hyperhidrosis can cause breakout sweating in previously unaffected areas of the body. Some people also find the effects wear off over five to ten years. </p>
<p>Fortunately, compensatory hyperhidrosis is rare after Botox. In fact, there are few complications. </p>
<p>If you are concerned about excessive sweating, consult your GP, who can refer you to a specialist if required.</p><img src="https://counter.theconversation.com/content/22060/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rodney Sinclair does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Everybody sweats, some more than others. It’s a physiological reaction to heat and the body’s mechanism to regulate core temperate. Individual sweat rates vary and are influenced by factors such as ambient…Rodney Sinclair, Professor Dermatology, Honorary, Epworth Hospital, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.