tag:theconversation.com,2011:/africa/topics/exercise-physiology-15140/articlesExercise physiology – The Conversation2022-08-04T12:20:41Ztag:theconversation.com,2011:article/1849172022-08-04T12:20:41Z2022-08-04T12:20:41ZWhat are muscle knots? An exercise physiologist explains what those tight little lumps are and how to get rid of them<figure><img src="https://images.theconversation.com/files/477467/original/file-20220803-25-nptdop.jpg?ixlib=rb-1.1.0&rect=386%2C25%2C4901%2C3682&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Those stiff, painful spots can take up to two weeks to go away on their own.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/self-acupressure-for-relaxing-shoulder-and-backache-royalty-free-image/480619308">Sophie Walster/iStock via Getty Images Plus</a></span></figcaption></figure><p>Imagine you’ve just completed a tough upper-body workout. Your muscles feel a bit tired, but all in all you’re able to go about the rest of your day just fine.</p>
<p>The next morning, you wake up and realize the back of your shoulder blade feels stiff. When you rub your shoulder muscles, it feels like you’re prodding a little gumball under your skin. Every time you try to move it around, the area feels tight, with slight pangs of pain.</p>
<p>Over the course of the next few days, your back slowly loosens up and eventually your shoulder returns to feeling normal. It’s probably something you’d like to avoid or minimize in the future if possible, though. So what was going on with that muscle knot?</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/471725/original/file-20220629-17-ds1l1k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Model of adult person's musculature with red dots showing potential locations for muscle knots" src="https://images.theconversation.com/files/471725/original/file-20220629-17-ds1l1k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/471725/original/file-20220629-17-ds1l1k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=551&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471725/original/file-20220629-17-ds1l1k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=551&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471725/original/file-20220629-17-ds1l1k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=551&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471725/original/file-20220629-17-ds1l1k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=692&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471725/original/file-20220629-17-ds1l1k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=692&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471725/original/file-20220629-17-ds1l1k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=692&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Knots frequently crop up in the skeletal muscles of the shoulder area.</span>
<span class="attribution"><span class="source">3D Human Anatomy/Zachary Gillen</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p><a href="https://scholar.google.com/citations?user=gn8ZiLMAAAAJ&hl=en&oi=ao">I’m an exercise physiologist</a>. The goal of much of my research is to understand how different movements and forms of exercise place stress on the muscles. Figuring out programs to maximize performance, regardless of training goal, goes beyond what to do during the workout – it’s also about how best to prepare for and recover from the stress exercise places on the body.</p>
<p>Some of the most common questions I’ve heard during my years as a personal trainer and researcher in this field involve muscle knots. What are they and how can you get rid of them when they happen?</p>
<h2>What are muscle knots?</h2>
<p>The knots you detect in your muscle, which may feel as small as a marble or even as large as a golf ball, are called <a href="https://doi.org/10.1016/j.pmrj.2015.01.024">myofascial trigger points</a>. The fascia is the thin layer of connective tissue that surrounds the muscle.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/477236/original/file-20220802-19-e1o9uh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="diagram of skeletal muscle with a closeup of bands of fibers with lumpy spots" src="https://images.theconversation.com/files/477236/original/file-20220802-19-e1o9uh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/477236/original/file-20220802-19-e1o9uh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=845&fit=crop&dpr=1 600w, https://images.theconversation.com/files/477236/original/file-20220802-19-e1o9uh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=845&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/477236/original/file-20220802-19-e1o9uh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=845&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/477236/original/file-20220802-19-e1o9uh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1061&fit=crop&dpr=1 754w, https://images.theconversation.com/files/477236/original/file-20220802-19-e1o9uh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1061&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/477236/original/file-20220802-19-e1o9uh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1061&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Inflammation is what causes the muscle fibers to feel as if a little pea is stuck inside.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Trigger_Point_Complex.jpg">Davidparmenter/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>When your muscle gets damaged – even just a little – it can cause inflammation in the bands of muscle and the fascial layer above. And that clump of inflamed tissue is a myofascial trigger point. The little lumps are typically tender to the touch and can limit your range of motion or lead to pain during various movements. Muscle knots don’t show up on medical imaging scans, and researchers are still trying to figure out the exact physiological mechanisms within the muscle that cause this reaction.</p>
<p>Myofascial trigger points tend to develop when a muscle is irritated by a new or more-strenuous-than-usual repetitive motion. For example, you may develop knots in the muscles you stressed the most during a particularly intense day of exercise. They can also crop up if you introduce a new movement pattern to your daily workout. Imagine adding a couple of days of running to your typical weekly routine of just lifting weights. Since running is a new movement, you may notice some knots in your calves, which you asked to do a lot of new work.</p>
<p>You don’t need to be a gym rat, though, to be familiar with muscle knots. For instance, if you are consistently hunched over a computer all day, you may notice knots developing in your upper back and shoulders. Most people wouldn’t consider sitting at a desk strenuous, but holding one position for hours at a time places stress on your muscles. Enter muscle knots.</p>
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<a href="https://images.theconversation.com/files/477468/original/file-20220803-12-nl5yjl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="young woman at laptop reaches up to her neck in discomfort" src="https://images.theconversation.com/files/477468/original/file-20220803-12-nl5yjl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/477468/original/file-20220803-12-nl5yjl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=436&fit=crop&dpr=1 600w, https://images.theconversation.com/files/477468/original/file-20220803-12-nl5yjl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=436&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/477468/original/file-20220803-12-nl5yjl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=436&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/477468/original/file-20220803-12-nl5yjl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=548&fit=crop&dpr=1 754w, https://images.theconversation.com/files/477468/original/file-20220803-12-nl5yjl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=548&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/477468/original/file-20220803-12-nl5yjl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=548&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Holding a position for too long can stress muscles.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/portrait-of-asian-woman-having-shoulder-pain-while-royalty-free-image/1357627187">Boy_Anupong/Moment via Getty Images</a></span>
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<h2>How do you get rid of muscle knots?</h2>
<p>One of the simplest solutions to the problem of muscle knots is to just wait. It takes time for the muscles to adapt to a new motion or recover from stress. Usually within a week or two a muscle knot <a href="https://doi.org/10.1179/106698106790819991">will resolve on its own</a>.</p>
<p>You can also help speed the process of recovery. Some options include <a href="https://doi.org/10.1155/2011/561753">massages</a>; <a href="https://doi.org/10.1080/10669817.2020.1822618">dry needling</a>, which involves injecting a very thin needle into the trigger point to attempt to break up some of the tissue and increase blood flow to the area; and even <a href="https://doi.org/10.1016/j.jbmt.2021.06.016">electrical stimulation</a>. The goal of each technique is to decrease the tautness of the fascia and muscle in the area and <a href="https://doi.org/10.1016/j.jmpt.2012.10.005">increase blood flow</a>. <a href="https://doi.org/10.1089/acm.2014.0160">More blood passing through</a> <a href="https://doi.org/10.1152/ajpendo.00373.2001">provides nutrients and oxygen</a> to the damaged tissue, <a href="https://doi.org/10.1123/ijspp.2015-0779">enhancing recovery</a>. </p>
<p>While these techniques <a href="https://doi.org/10.1097/PHM.0000000000000728">are worth considering</a>, there are other more cost-effective things you can do yourself at home. A fairly simple way to <a href="https://doi.org/10.1016/j.ptsp.2010.02.003">help alleviate muscle</a> <a href="https://doi.org/10.1016/0304-3959(86)90211-3">knots is stretching</a>. Stretching may be particularly valuable if you typically sit in an awkward position all day long. Muscles held that way under consistent stress for several hours benefit from being put through different ranges of motion. For example, after sitting for a while, some simple shoulder rolls and neck rotations can alleviate some of the tension in those muscles, helping to avoid or reduce the accumulation of muscle knots.</p>
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<a href="https://images.theconversation.com/files/471726/original/file-20220629-16-49a2d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a foam roller, a PVC pipe and two balls" src="https://images.theconversation.com/files/471726/original/file-20220629-16-49a2d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/471726/original/file-20220629-16-49a2d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=814&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471726/original/file-20220629-16-49a2d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=814&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471726/original/file-20220629-16-49a2d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=814&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471726/original/file-20220629-16-49a2d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1023&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471726/original/file-20220629-16-49a2d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1023&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471726/original/file-20220629-16-49a2d.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">You can use several kinds of props to help with self-myofascial release.</span>
<span class="attribution"><span class="source">Zachary Gillen</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>Another method you can try at home is called <a href="https://doi.org/10.1016/j.jbmt.2016.11.006">self-myofascial release</a>. The idea behind it is the same as massaging, except this method can be done in the comfort of your own home using a <a href="https://doi.org/10.1519/jsc.0b013e3182956569">foam roller</a>, <a href="https://doi.org/10.5114/biolsport.2018.78055">rolling device</a>, a hard ball, like a lacrosse ball or softball, or even a small piece of PVC pipe.</p>
<p>For example, if you have knots in the quadriceps muscle group on the front of your thigh, you can lie on a foam roller and gently roll your leg back and forth on it. Alternatively, you can roll the device up and down the muscle group, keeping the pressure within your comfort range. Because you apply as much pressure as you like, you’re able to work within your own pain tolerance – a benefit, since it can be uncomfortable to alleviate myofascial trigger points. You can use this technique across the body anywhere you have muscle knots.</p>
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<a href="https://images.theconversation.com/files/477470/original/file-20220803-19-zgcuud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="man seated on the floor with legs outstretched leans calf on foam roller" src="https://images.theconversation.com/files/477470/original/file-20220803-19-zgcuud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/477470/original/file-20220803-19-zgcuud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/477470/original/file-20220803-19-zgcuud.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/477470/original/file-20220803-19-zgcuud.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/477470/original/file-20220803-19-zgcuud.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/477470/original/file-20220803-19-zgcuud.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/477470/original/file-20220803-19-zgcuud.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>
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<span class="caption">Foam rolling is a self-directed way to massage out the knots.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/home-workout-with-foam-roller-royalty-free-image/1367817911">martin-dm/E+ via Getty Images</a></span>
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<p>While they can be annoying, muscle knots are nothing to worry about. Remember, being consistent with exercise habits and moving throughout the day can help keep knots from developing in your muscles in the first place. If you do notice muscle knots popping up, simply stretching at the end of the day or going through some self-myofascial release techniques are simple, effective ways to help alleviate this issue and avoid future problems.</p><img src="https://counter.theconversation.com/content/184917/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Zachary Gillen 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>Researchers are still trying to figure out exactly what happens within muscle to create knots, also known as myofascial trigger points. But they do know some ways you can avoid or alleviate them.Zachary Gillen, Assistant Professor of Exercise Physiology, Mississippi State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1646552021-09-13T12:14:14Z2021-09-13T12:14:14ZWhat happens when your foot falls asleep?<figure><img src="https://images.theconversation.com/files/417576/original/file-20210824-17-1ma6ikr.jpg?ixlib=rb-1.1.0&rect=494%2C1005%2C4994%2C2982&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">That pins-and-needles feeling can come from sitting in the same position for a while.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/legs-of-a-girl-wearing-dotted-socks-royalty-free-image/1195442823">Westend61 via Getty Images</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
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<blockquote>
<p><strong>What happens when your foot falls asleep? – Helen E., age 8, Somerville, Massachusetts</strong></p>
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<p>Imagine you’ve just sat down to watch your favorite TV show. You decide to snuggle in with your legs crisscrossed because you find it more comfortable that way.</p>
<p>When the episode ends, you try to stand up and suddenly your right foot isn’t working. At first you just can’t move it, then it feels like it has pins and needles all over it. For a minute or two it feels uncomfortable and weird, but soon enough you are able to stand up and walk around normally.</p>
<p>What just happened?</p>
<p><a href="https://scholar.google.com/citations?user=gn8ZiLMAAAAJ&hl=en&oi=ao">I’m an exercise physiologist</a> – a scientist who studies what happens to our bodies when we move and exercise. The goal of much of my research has been to understand how the brain talks to and controls the different parts of our bodies. When your foot falls asleep, there is something wrong with the communication between your brain and the muscles in that area.</p>
<p>Every time you decide to move your body, whether it’s standing up, walking around or playing sports, your brain sends signals to your muscles to make sure they move correctly. When the brain is unable to talk with a muscle or groups of muscles, some weird things can happen – including that part of your body getting that weird falling-asleep sensation.</p>
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<figcaption><span class="caption">An animation explains how the nervous system works.</span></figcaption>
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<p>It usually starts with a sense of numbness or tingling in that area. This sensation, which people often also call “pins and needles,” is technically known as <a href="https://www.racgp.org.au/afp/2015/march/paraesthesia-and-peripheral-neuropathy/">paresthesia</a>.</p>
<p>Some people mistakenly think a lack of blood flow causes this feeling. They imagine the “asleep” feeling happens when your blood, which carries nutrients all over your body, is unable to get to your foot. But that’s not right.</p>
<p>When your foot falls asleep, it’s actually because the <a href="https://doi.org/10.2165/00007256-200232060-00003">nerves that connect the brain to the foot</a> are getting squished thanks to the position you’re sitting in. Remember, it’s these nerves that carry messages back and forth to let your brain and your foot communicate with each other. If the nerves have been compressed for a little while, you won’t have much feeling in your foot because it can’t get its normal messages through to your brain about how it feels or if it’s moving.</p>
<p>Once you start to move around again, the pressure on the nerves is released. They “wake up” and you’ll start to notice a “pins and needles” feeling. Don’t worry, that feeling will only last for a few minutes and then everything will feel normal again.</p>
<p>Now comes the important question: Is this dangerous? Most of the time, when your foot, or any other body part, falls asleep, it is temporary and nothing to worry about. In fact, since it lasts for only a minute or two, you may not even remember it happened by the end of the day.</p>
<p>Even though it’s not causing any permanent damage, you might still want to avoid the uncomfortable feeling that comes when your foot falls asleep. Here are a couple of tips that may help:</p>
<ul>
<li>Switch your position often.</li>
<li>Don’t cross your legs for very long.</li>
<li>When you are sitting for a long time, try standing up every so often.</li>
</ul>
<p>You probably can’t 100% prevent your foot from ever falling asleep. So don’t worry when it happens every once in a while. It’ll go away pretty quickly – and maybe it can remind you of all the important brain messages your nerves are usually transmitting without your even noticing.</p>
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<p class="fine-print"><em><span>Zachary Gillen 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>An exercise physiologist explains how it’s a problem of communication between your brain and your body.Zachary Gillen, Assistant Professor of Exercise Physiology, Mississippi State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1554702021-02-25T19:02:51Z2021-02-25T19:02:51ZCOVID vaccines won’t be compulsory for the Tokyo Olympics. But if offered, here’s what athletes need to know<figure><img src="https://images.theconversation.com/files/386039/original/file-20210224-19-1pn7pgb.jpg?ixlib=rb-1.1.0&rect=0%2C5%2C998%2C660&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/tokyo-japan-january-6-2021-olympic-1892990605">Sayuri Inoue/www.shutterstock.com</a></span></figcaption></figure><p>Brisbane has <a href="https://www.abc.net.au/news/2021-02-25/brisbane-preferred-host-2032-summer-olympics-ioc-announces/13190386">just been confirmed</a> as the preferred host for the 2032 Olympics. But Olympic organisers have more immediate concerns in mind — how to safely run the postponed Tokyo Olympics, due to start in July.</p>
<p>That’s why the International Olympic Committee (IOC) has released its “<a href="https://www.olympic.org/tokyo-2020-playbooks">playbooks</a>”, a set of rules to help ensure the safety and health of athletes and officials, as well as the wider community, during the pandemic.</p>
<p>Requirements for athletes include COVID-19 testing and using a contact-tracing app, but COVID-19 vaccination is not mandatory. It is, however, <a href="https://www.skysports.com/olympics/news/15234/12199547/tokyo-olympics-ioc-to-encourage-athletes-to-get-covid-19-vaccine-but-only-after-priority-groups">recommended</a> <a href="https://www.olympic.org/tokyo-2020-playbooks">when available</a> in athletes’ home countries.</p>
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<p>So what do athletes <a href="https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(21)00082-5/fulltext">need to think about</a> if offered a COVID-19 vaccine?</p>
<h2>Will athletes be vaccinated before July?</h2>
<p>Most COVID-19 vaccine programs around the world, <a href="https://theconversation.com/what-will-australias-covid-vaccination-program-look-like-4-key-questions-answered-150748">including Australia’s</a>, are prioritising high-risk people such as those in aged care and front-line workers. And the IOC <a href="https://www.olympic.org/tokyo-2020-playbooks">is not recommending</a> athletes “jump the queue” to get priority vaccination. So, under most national vaccination programs, most Olympic athletes will not have been offered vaccines by July. </p>
<p>But some athletes may be offered vaccinations before then, and future international sporting events may include similar vaccination recommendations.</p>
<p>Guidelines for vaccinating athletes, including Australia’s, before the Olympics have not been publicly released. But discussion on details of “<a href="https://www.newsweek.com/coronavirus-covid-who-vaccine-certificates-vaccination-passports-travel-requirements-1554777">vaccination passports</a>” is <a href="https://theconversation.com/the-covid-vaccine-is-here-when-and-to-whom-will-we-need-to-prove-weve-had-it-155122">growing</a>. It is likely that recommendations would include all doses being completed (usually one or two doses) before travel. Injections would need to be three to 12 weeks apart, depending on the vaccine. But if it’s a single-dose vaccine, there may be a recommendation for allowing <a href="https://www.huffingtonpost.com.au/entry/how-long-before-coronavirus-vaccine-works_l_5fd6c66fc5b6218b42ea3760">about a month</a> for protection to build up before travel.</p>
<p>So, for any vaccine, preparation and planning will be important.</p>
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Read more:
<a href="https://theconversation.com/for-now-the-tokyo-olympics-will-go-ahead-but-at-what-cost-154851">For now, the Tokyo Olympics will go ahead. But at what cost?</a>
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<h2>How about side-effects?</h2>
<p>For most of us, planning to receive a COVID-19 vaccine might include thinking about travel and work schedules, and the possibility a vaccine reaction could mean a day off work, but likely little more. </p>
<p>For an elite athlete with detailed training and recovery plans, with potentially restricted access to training locations, and the possibility of a vaccine reaction, it gets a little more complicated.</p>
<p>Reassuringly, rates of <a href="https://onbiostatistics.blogspot.com/2011/12/serious-adverse-events-sae-vs-severe.html">severe or serious</a> adverse events after COVID-19 vaccines are very <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2820%2932623-4/fulltext">low</a> — at less than <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa2034577">1%</a> of those vaccinated.</p>
<p>But the rates of mild or moderate vaccine reactions are higher. And unlike other vaccines, reactions to various COVID vaccines tend to be more common in <a href="https://www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/reactogenicity.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fvaccines%2Fcovid-19%2Finfo-by-manufacturer%2Fpfizer%2Freactogenicity.html">younger adults (18-55 years old)</a> than older adults. </p>
<p>Some vaccines (such as the Oxford/AstraZeneca vaccine) tend to have more systemic reactions such as headache and fever <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)32466-1/fulltext#seccestitle150">after the first dose</a>; others (such as the Pfizer/BioNTech) <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa2034577">after the second</a>.</p>
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Read more:
<a href="https://theconversation.com/covid-vaccines-have-been-developed-in-record-time-but-how-will-we-know-theyre-safe-153888">COVID vaccines have been developed in record time. But how will we know they're safe?</a>
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<p>For people receiving the <a href="https://www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/reactogenicity.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fvaccines%2Fcovid-19%2Finfo-by-manufacturer%2Fpfizer%2Freactogenicity.html">Pfizer/BioNTech vaccine</a>, about 89% reported local reactions (mostly vaccine site pain, with 51% reporting mild pain with no impact on daily activity). About 83% reported systemic reactions (mainly headache or fatigue, mostly mild). </p>
<p>For the <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)32466-1/fulltext#seccestitle150">Oxford/AstraZeneca vaccine</a>, 88% reported local reactions and 86% reported a systemic reaction. </p>
<p>For both vaccines, the reactions were mostly mild, not impacting activities, were reported in the first one or two days after vaccination, and resolved within a few days.</p>
<p>These reactions might have little impact on most of our daily lives but could stop an athlete training for a day or so.</p>
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Read more:
<a href="https://theconversation.com/weekly-dose-paracetamol-may-be-our-favourite-mild-painkiller-but-it-doesnt-work-for-everything-57967">Weekly Dose: paracetamol may be our favourite mild painkiller, but it doesn't work for everything</a>
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<p>Some researchers who conducted these vaccine studies are considering whether taking paracetamol before vaccination might help reduce reactions. For instance, reactions to the Oxford/AstraZeneca vaccine <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31604-4/fulltext">were reduced</a> for people who took paracetamol, without compromising the immune response.</p>
<p><a href="https://www.cbsnews.com/news/covid-19-vaccine-shot-painkillers-doctors/">But not all doctors agree</a> this is a good idea, as <a href="https://insights.ovid.com/pubmed?pmid=29465480">studies</a> with the influenza vaccine showed less effective responses when people tool paracetamol beforehand.</p>
<p>What does that mean for athletes? We know athletes <a href="http://eir-isei.de/2013/eir-2013-086-article.pdf">lose training time</a> when suffering from common cold symptoms. We also know vaccine reaction rates are <a href="https://www.cdc.gov/vaccines/covid-19/info-by-product/pfizer/reactogenicity.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fvaccines%2Fcovid-19%2Finfo-by-manufacturer%2Fpfizer%2Freactogenicity.html">higher in younger adults</a>. So athletes may need to consider the possibility of a mild reaction. And it would be wise to plan for rest and recovery in the few days after their injection.</p>
<h2>Does exercising help?</h2>
<p>Fortunately, exercise appears to be a friend of vaccination. Athletes show <a href="https://pubmed.ncbi.nlm.nih.gov/31580932/">stronger responses</a> to the influenza vaccine than healthy adults of similar age. So athletes’ immune response after a COVID vaccine might be particularly strong. However, there have been no studies to test this specifically.</p>
<p>What we do know is that exercise causes <a href="https://jitc.biomedcentral.com/articles/10.1186/s40425-017-0231-8">immediate and long-term changes</a> in our immune systems. A single bout of exercise causes release of signalling molecules and increases the number of immune cells circulating in the blood. Researchers believe that if exercise is timed immediately before or after a vaccination, these changes help our immune systems react to the <a href="https://www.sciencedirect.com/science/article/pii/S0889159113005023?via%3Dihub">vaccination</a>.</p>
<p>Exercise close to the vaccination itself might also help reduce common COVID-19 vaccine reactions. </p>
<p>Exercise immediately before receiving a vaccine <a href="https://pubmed.ncbi.nlm.nih.gov/30301642/">reduced rates</a> of local and systemic reactions, although this was after two different vaccines, influenza and HPV (human papillomavirus). We don’t know for sure whether this will be the same for the COVID-19 vaccines because no one has actually tested it yet.</p>
<h2>In a nutshell</h2>
<p>So, athletes need to plan ahead. They might train before the injection, and take paracetamol in advance, if their doctor advises them to. They might need to plan for a reduced training load in the days after vaccination. They might also make sure they start the doses far enough ahead to complete all doses before travelling.</p>
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<strong>
Read more:
<a href="https://theconversation.com/all-the-olympics-are-a-stage-and-all-the-athletes-merely-players-the-rich-history-of-the-modern-games-61904">All the Olympics are a stage, and all the athletes merely players: the rich history of the modern Games</a>
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<img src="https://counter.theconversation.com/content/155470/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kate Edwards has received funding from The Bill and Melinda Gates Foundation, The Financial Markets Foundation for Children, Sydney Catalyst and the Ramaciotti Foundation.</span></em></p>For elite athletes, even mild COVID-19 vaccine side effects can throw their training plans off course. But they can plan ahead.Kate Edwards, Associate Professor, Sydney School of Health Sciences, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1240662019-12-18T13:36:55Z2019-12-18T13:36:55ZTracking your heart rate? 5 questions answered about what that number really means<figure><img src="https://images.theconversation.com/files/307532/original/file-20191217-58315-1g956jn.jpg?ixlib=rb-1.1.0&rect=286%2C429%2C5696%2C3922&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">It's one of your body's most basic vital signs.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-human-hand-wearing-smart-watch-471411131">Andrey_Popov/Shutterstock.com</a></span></figcaption></figure><p>The rise of <a href="https://theconversation.com/us/topics/wearable-technology-5180">wearable fitness trackers</a> has increased the number of people monitoring their heart rate, both throughout the day and during exercise.</p>
<p>Whether you’re an athlete trying to gain the <a href="https://theconversation.com/wearable-technologies-help-olympians-achieve-top-performance-91721">competitive edge</a>, a weekend warrior tracking progress or someone who is just trying to improve your health, consider heart rate a valuable tool in understanding the work of your amazing body as it achieves those first steps, that next 5K or even Olympic gold.</p>
<p>Heart rate is one of your body’s most basic vital signs, yet many people have questions about what heart rate really tells them. What should your target heart rate be during exercise? Does it even matter?</p>
<h2>1. What is your heart rate?</h2>
<p>First, the basics: Your <a href="https://www.heart.org/en/health-topics/high-blood-pressure/the-facts-about-high-blood-pressure/all-about-heart-rate-pulse">heart rate</a>, also sometimes called your pulse rate, is the number of times your heart contracts per minute.</p>
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<a href="https://images.theconversation.com/files/307533/original/file-20191217-58315-jp3dc3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307533/original/file-20191217-58315-jp3dc3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/307533/original/file-20191217-58315-jp3dc3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307533/original/file-20191217-58315-jp3dc3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307533/original/file-20191217-58315-jp3dc3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307533/original/file-20191217-58315-jp3dc3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307533/original/file-20191217-58315-jp3dc3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307533/original/file-20191217-58315-jp3dc3.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">The left ventricle does the bulk of the work, pumping your blood through your aorta off to the rest of your body.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/circulation-blood-through-heart-cross-sectional-1044399025">Olga Bolbot/Shutterstock.com</a></span>
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<p><a href="https://scholar.google.com/citations?user=uXcM0scAAAAJ&hl=en&oi=ao">Physiologists like me</a> focus on the contractions of the left ventricle, the chamber of the heart that generates pressure to drive blood out through the aorta and on to the entire body. The heart’s pumping capacity directly relates to its ability to deliver oxygen to the body’s organs.</p>
<p>If you’re running up the stairs or hauling something heavy, your muscles and organs are going to need more oxygen to help power your actions. And so your heart beats faster.</p>
<h2>2. How do you measure heart rate?</h2>
<p>The easiest way to measure heart rate is <a href="https://www.healthline.com/health/how-to-check-heart-rate#target-heart-rates">to find your pulse</a> and count the number of pulses felt over the course of one minute.</p>
<p>In adults, the best places to feel for a pulse are large arteries that are near the surface of the skin, such as the carotid at the side of your neck or the radial on the underside of your wrist. If feeling for the carotid pulse, don’t press hard enough to disrupt blood flow to and from the head.</p>
<p>More recently, watches and other wrist-based fitness monitors have incorporated optical sensors to track heart rate. These <a href="https://support.apple.com/en-us/HT204666">wearable devices</a> use technology called <a href="https://doi.org/10.1088/0967-3334/28/3/R01">photoplethysmography</a>, which has been around since the <a href="https://iopscience.iop.org/article/10.1088/0031-9155/19/3/003">mid-1970s</a>. Each beat of your heart sends a little surge of blood through your veins. The monitor detects this by shining green light onto your skin and then analyzing the light that gets refracted back by the <a href="https://theconversation.com/blood-in-your-veins-is-not-blue-heres-why-its-always-red-97064">red blood flowing underneath</a>. </p>
<p>This kind of heart-rate monitoring is popular, but it has <a href="https://theconversation.com/some-heart-rate-monitors-give-less-reliable-readings-for-people-of-colour-121007">shortcomings for people with dark skin</a>.</p>
<p>Some exercisers rely on chest straps that measure electrical activity and then transmit that signal to a watch or other display device. This technique depends on picking up the electrical signals within your body that direct your heart to beat.</p>
<p>For the most part, the two techniques are <a href="https://doi.org/10.1186/s13102-018-0098-0">about equally accurate</a>.</p>
<h2>3. What controls your heart rate?</h2>
<p>Your autonomic nervous system is mostly in charge of your heart rate. That’s the portion of the nervous system that runs without your even thinking about it.</p>
<p>In <a href="https://doi.org/10.1136/hrt.2005.079400">healthy hearts</a>, as someone begins to exercise, the autonomic nervous system does two things. First, it removes the “brake” that keeps your heart beating slowly and steadily under normal conditions. And then it “hits the gas” to actively stimulate the heart to beat faster.</p>
<p>In addition, the amount of blood ejected from the left ventricle with each heart beat – called the stroke volume – increases, particularly during the initial stages of exercise. </p>
<p>Together, higher stroke volume and more beats per minute mean the amount of blood delivered by the heart increases to match the increased oxygen demand of exercising muscles.</p>
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<a href="https://images.theconversation.com/files/307525/original/file-20191217-58292-13hdxry.jpg?ixlib=rb-1.1.0&rect=1101%2C0%2C6247%2C4869&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/307525/original/file-20191217-58292-13hdxry.jpg?ixlib=rb-1.1.0&rect=1101%2C0%2C6247%2C4869&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307525/original/file-20191217-58292-13hdxry.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307525/original/file-20191217-58292-13hdxry.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307525/original/file-20191217-58292-13hdxry.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307525/original/file-20191217-58292-13hdxry.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307525/original/file-20191217-58292-13hdxry.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307525/original/file-20191217-58292-13hdxry.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>
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<span class="caption">Working hard or hardly working?</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sport-watch-run-woman-checking-smartwatch-713507023">Maridav/Shutterstock.com</a></span>
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<h2>4. How does heart rate relate to exercise intensity?</h2>
<p>As your exercise session becomes more intense and more work is done, your heart beats faster and faster. This relationship means you can use heart rate as a surrogate measure for the intensity of exertion, relative to one’s maximal heart rate.</p>
<p>Your maximum heart rate is the fastest your heart can functionally beat. So how do you know what your number actually is?</p>
<p>In order to determine your maximum heart rate, you could do increasingly difficult exercise, like walking on a treadmill and increasing the grade each minute, until you can no longer keep up. But it’s much more common (and often safer!) to estimate it. Many studies have identified that <a href="https://www.ncbi.nlm.nih.gov/pubmed/2188839">maximal heart rate goes down with age</a>, and thus age is included in all estimation equations.</p>
<p>The most common and simplest prediction equation is: Maximal heart rate is equal to 220 minus your age. From that number, you can calculate a percentage of maximum to provide <a href="https://www.heart.org/en/healthy-living/fitness/fitness-basics/target-heart-rates">target heart rate ranges</a> in the moderate (50%-70%) or vigorous (70%-85%) categories of exercise, important in terms of meeting the <a href="https://www.cdc.gov/physicalactivity/basics/index.htm">recommended levels of exercise</a> for overall health benefits.</p>
<p><iframe id="nRCoQ" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/nRCoQ/4/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Interestingly, this equation, while perhaps most common, <a href="https://www.researchgate.net/publication/237258265_The_surprising_history_of_the_HRmax220-age_equation">wasn’t based upon empirical research</a> and is not as accurate as others you can try, like <a href="https://doi.org/10.1016/S0735-1097(00)01054-8">your age multiplied by 0.7 and then subtracted from 208</a>.</p>
<p>As with any prediction equation, there is always some individual variability. To accurately know your max heart rate at your current age, you’d need to measure it during maximal exercise.</p>
<h2>5. Why is exercise intensity important?</h2>
<p>In addition to helping you to know whether you’re meeting general recommendations for exercise, knowing the intensity of a given workout session can be of benefit in other ways.</p>
<p>First, the body uses different primary sources of energy to fuel exercise of different relative intensities. During lower-intensity exercise, a greater proportion of the energy you’re using comes from fat sources in your body. During higher-intensity exercise, more of the energy utilized comes from carbohydrate sources.</p>
<p>But don’t slow that treadmill down just yet if you’re hoping to drop pounds of fat. Lower-intensity exercise also requires less energy overall. So, to burn the same amount of calories with lower-intensity exercise, you’ll need to exercise for longer than you would at a higher intensity.</p>
<p>Secondly, the intensity of a set amount of work – like a particular speed/grade combo on the treadmill, or a certain wattage on a rowing ergometer – reflects your overall fitness. Once you can complete the same amount of work at a lower relative intensity – like if you can run a mile in the same amount of time but with your heart beating slower than it did in the past – you know you’ve gained fitness. And increased fitness is associated with a <a href="https://doi.org/10.1001/jamanetworkopen.2018.3605">decrease in death from any cause</a>.</p><img src="https://counter.theconversation.com/content/124066/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anne R. Crecelius 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>Trying a new exercise routine? Strapping on a new wearable monitor? An expert in human physiology explains the ins and outs of your heart rate and why it’s a valuable number to understand.Anne R. Crecelius, Associate Professor of Health and Sport Science, University of DaytonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1255892019-11-12T12:53:49Z2019-11-12T12:53:49ZWhy exercise is less helpful in losing weight than simply eating less<figure><img src="https://images.theconversation.com/files/297929/original/file-20191021-56228-1a3ag5x.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1000%2C666&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Why does it seem like no matter how much you exercise, your weight stays the same?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/es/image-photo/sports-man-eating-banana-during-training-1078314074">Mladen Zivkovic / Shutterstock</a></span></figcaption></figure><p>I tend to be overweight, and for the last few years my blood glucose levels have been putting me on the brink of Type 2 diabetes. I love my food, and it is often part of my social commitments. I’m a Spaniard, so there’s also the occasional tapas and glass of wine, or maybe a martini on Saturdays.</p>
<p>As a <a href="https://scientia.eus/team/juan-ignacio-perez-iglesias/">physiologist</a>, I know I need to take steps to control my blood glucose and weight. So early every morning, I spend a considerable amount of time pedaling away on a stationary bike. </p>
<p>When I started this morning activity, I lost several pounds in the first two or three weeks. Then I increased my cycling time, from 40 to 60 minutes a day, and lost another few pounds. </p>
<p>Now, however, I’ve been following this regimen for nearly two years, and my weight has obstinately refused to go down. No matter how much I exercise, it barely drops. I can’t spend any more time pedaling. The day isn’t long enough. Neither is the night.</p>
<p>It is discouraging to get on a bike early in the morning, pedal away madly for over an hour and weigh the same as before. The only thing I manage to do during the work week is knock off the weight I put on over the weekend.</p>
<p>The apparent lack of physiological logic in all this irks me. </p>
<p>In my lectures at Spain’s <a href="https://www.ehu.eus/en">University of the Basque Country</a>, the syllabus covers energy balance — the difference between your energy input, or calories consumed, and your energy output, or calories burnt. I teach students that <a href="https://www.ncbi.nlm.nih.gov/pubmed/14692598">when activity increases, the metabolic rate rises</a>. </p>
<p>So if the energy absorbed in the form of food is constant, more metabolic activity should bring about a reduction in the energy available for growth, even to the point of negative growth – that is, weight loss. Right?</p>
<h2>Why isn’t exercise helping me lose weight?</h2>
<p>Science has <a href="https://theconversation.com/is-exercise-still-important-to-weight-loss-absolutely-a-doctor-says-103880">struggled to provide a satisfying and consistent answer</a> to this common frustration.</p>
<p>According to anthropologist Herman Pontzer of Duke University, when physical activity is increased in the long term, daily energy expenditure also rises – but <a href="https://www.sciencedirect.com/science/article/pii/S0960982215015778">less than one would expect</a>. Even as activity increases, the body’s total daily energy expenditure rises more and more slowly, until the number of calories burnt daily becomes virtually constant. </p>
<p>In other words, the body adapts to changing circumstances. If expenditure is more or less constant, then, the body compensates for increased physical activity by reducing the energy it spends on other, nonessential functions.</p>
<p><a href="https://www.physiology.org/doi/abs/10.1152/physiol.00027.2018">Pontzer’s hypothesis</a>, which was developed working alongside a team of doctors, would explain why I tend to feel cold – even on very hot days – and why I feel colder on mornings when I’ve exercised intensively. What I make my body pay for in exercise, my metabolism “charges” me for by reducing heat generation.</p>
<p>So while moderate physical activity leads to a reduction in <a href="https://www.sciencedirect.com/science/article/pii/S0960982215015778?via%3Dihub">nonessential physiological activities</a>, the reduced functionality triggered by high levels of physical activity may actually be <a href="https://www.physiology.org/doi/full/10.1152/japplphysiol.00622.2016">harmful to human health</a>.</p>
<p><a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/ajhb.10152">Research shows</a> that heavy physical activity can alter the ovarian cycle in women, diminish sperm production in men, lower levels of sexual hormones in the blood and reduce sex drive. </p>
<p>Under conditions of very high activity, the effects on reproductive function become more obvious – consider the <a href="https://academic.oup.com/jcem/article/90/11/6022/2838411">delayed onset of puberty in young gymnasts</a>, for example. The <a href="https://www.sciencedirect.com/science/article/pii/S2095254618301005">immune system suffers</a>, as does the body’s ability <a href="https://www.sciencedirect.com/science/article/pii/S0960982215015778#bib5">to repair damaged tissue</a>. </p>
<p>So while it is healthy for many reasons to <a href="https://theconversation.com/keeping-fit-how-to-do-the-right-exercise-for-your-age-108851">regularly engage in moderate physical activity</a>, that activity does not have the slimming effects often attributed to it. And increasing the amount you exercise won’t change that.</p>
<h2>How to lose weight</h2>
<p>You don’t want to hear this any more than I do, but <a href="https://theconversation.com/how-to-lose-weight-and-keep-it-off-according-to-science-110674">controlling calorie intake</a> – difficult as that is – is a more effective way to control body weight. </p>
<p>The body adapts to a lack of food, <a href="https://journals.lww.com/acsm-essr/fulltext/2015/07000/Constrained_Total_Energy_Expenditure_and_the.3.aspx">as it does to increased physical activity</a>. In this case, it saves energy by reducing the speed of various physical processes, including metabolic activity – but not enough to offset the reduction in calories.</p>
<p>When you eat less, <a href="https://www.sciencedirect.com/science/article/pii/S1568163710001029">body temperature is also affected</a>: Reducing food intake <a href="https://www.ncbi.nlm.nih.gov/books/NBK236229/#_ddd00166_">tends to make people feel colder</a>. Eating less entails a slower physiological life and, to a certain extent, a more efficient one – that’s why, scientists are fairly confident, <a href="https://theconversation.com/comer-menos-alarga-la-vida-111665">eating less is tied to longevity</a>. </p>
<p>It’s not my place to advise anyone on their habits. But here’s how I’ve chosen to change my behavior based on this information.</p>
<p>First, I eat less than I used to and am more careful about what I eat. But I confess that I still overindulge occasionally. I’ve also moderated my physical activity. These days, I do about 100 miles a week on the stationary bike and walk whenever I get the chance.</p>
<p>So far I have not found life unbearable. Type 2 diabetes is still hanging over my head like the sword of Damocles, but I’m confident I’m on the right path.</p><img src="https://counter.theconversation.com/content/125589/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Juan Ignacio Pérez Iglesias no recibe salario, ni ejerce labores de consultoría, ni posee acciones, ni recibe financiación de ninguna compañía u organización que pueda obtener beneficio de este artículo, y ha declarado carecer de vínculos relevantes más allá del cargo académico citado.</span></em></p>A biologist frustrated by his own struggle to lose weight explains why simply exercising more and harder won’t melt the pounds away.Juan Ignacio Pérez Iglesias, Catedrático de Fisiología, Universidad del País Vasco / Euskal Herriko UnibertsitateaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1079632019-04-01T05:20:55Z2019-04-01T05:20:55ZHealth Check: what should our maximum heart rate be during exercise?<figure><img src="https://images.theconversation.com/files/266489/original/file-20190329-70982-1ozig6n.jpg?ixlib=rb-1.1.0&rect=31%2C23%2C5270%2C3505&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Exercising at your maximal heart rate isn't always effective.</span> <span class="attribution"><span class="source">Izf/Shutterstock</span></span></figcaption></figure><p>You have your runners on, your FitBit is charged, but now what? </p>
<p>When you exercise, your heart and breathing rates increase, delivering greater quantities of oxygen from the lungs to the blood, then to exercising muscles. </p>
<p>Determining an optimal heart rate for exercise depends on your exercise goal, age, and current fitness level. </p>
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Read more:
<a href="https://theconversation.com/what-should-my-heart-rate-be-and-what-affects-it-98945">What should my heart rate be and what affects it?</a>
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<p>Heart rate and exercise intensity share a direct, linear relationship: the more intense the exercise, the higher the heart rate.</p>
<p>When you exercise at the highest possible intensity, your heart will reach maximal heart rate (HRmax), the fastest rate it is capable of beating. </p>
<p>But exercising at a maximal heart rate (HRmax) for every exercise session will not produce efficient fitness results. These high intensities can rarely be sustained, negating the potential benefit of the exercise. </p>
<h2>Exercise makes your heart more efficient</h2>
<p>Typical resting heart rate can vary quite substantially between people and even within an individual. Around 60-80 beats per minute (BPM) for adults is common.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/266242/original/file-20190328-139380-iazkk7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/266242/original/file-20190328-139380-iazkk7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/266242/original/file-20190328-139380-iazkk7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/266242/original/file-20190328-139380-iazkk7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/266242/original/file-20190328-139380-iazkk7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/266242/original/file-20190328-139380-iazkk7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/266242/original/file-20190328-139380-iazkk7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/266242/original/file-20190328-139380-iazkk7.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>
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<span class="caption">Heart rate can be easily be measured with devices like FitBits and Apple Watches, although they have their limitations.</span>
<span class="attribution"><span class="source">Andres Urena/Unsplash</span></span>
</figcaption>
</figure>
<p>Improving your aerobic fitness reduces your resting heart rate, as the heart becomes more efficient with each beat. An athlete’s resting heart rate, for instance, is typically around 40 BPM.</p>
<p>In fact, evidence suggests that <a href="https://physoc.onlinelibrary.wiley.com/doi/full/10.1113/jphysiol.2011.217125">long-term exercise training increases the size of the heart</a>, specifically the <a href="https://www.healthywa.wa.gov.au/Articles/F_I/How-your-heart-works">left ventricle</a>, a phenomenon known as “Athlete’s Heart”. A bigger heart means more blood can be pumped with each beat, and fewer beats per minute are required to maintain blood flow around the body. This is a beneficial physiological adaptation allowing athletes to exercise at higher intensities for longer. </p>
<h2>How to calculate your maximal heart rate</h2>
<p>There is substantial variation in HRmax. The only true method of determining HRmax is to conduct a maximal exercise test. But HRmax can be estimated using formulas based on age. </p>
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<strong>
Read more:
<a href="https://theconversation.com/measuring-up-this-year-aim-for-fitness-over-fat-loss-for-long-term-success-52002">Measuring up: this year, aim for fitness over fat loss for long-term success</a>
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<p>The authors of a <a href="https://www.sciencedirect.com/science/article/pii/S0735109700010548?via%3Dihub">2001 study</a> proposed the following revised equation for estimating maximal heart rate: </p>
<p><strong>HRMax = 208 – (0.7 x Age)</strong></p>
<p>This means a 45-year-old would have a predicted HRmax of 177 BPM. </p>
<p>Indeed, our <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3935487/">genetics</a> can influence actual maximal heart rates from their predicted value. However, HRmax is not a major determinant of exercise or athletic performance. Far more important is our physiological efficiency.</p>
<p>When assessing heart rate, it’s also important to take into account the effects of emotions such as excitement or fear, stimulants like caffeine, and circulating hormones like adrenaline, all of which can increase heart rate.</p>
<h2>Is exercising at maximal heart rates unsafe?</h2>
<p>In short, the answer is no. For most adults, the risk of not doing <em>enough</em> exercise is far greater than that of doing excessive endurance exercise. </p>
<p>The health benefits of regular exercise are well established, although emerging evidence suggests <a href="https://journals.lww.com/acsm-healthfitness/fulltext/2014/07000/Have_a_Heart__Can_Too_Much_Exercise_Be_Bad_.11.aspx">excessive exercise</a> may not provide extra cardiovascular health benefits. </p>
<p>Likewise, there’s a higher chance a sedentary person will experience an acute cardiac event, like a heart attack, during exercise when they’re <a href="https://www.ahajournals.org/doi/full/10.1161/CIRCULATIONAHA.107.181485">unaccustomed to high-intensity exercise</a>, or they have a pre-existing heart condition. The maximal risk is 0.3 to 2.7 events per 10,000 person-hours.</p>
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Read more:
<a href="https://theconversation.com/health-check-in-terms-of-exercise-is-walking-enough-78604">Health Check: in terms of exercise, is walking enough?</a>
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<p>With a third of Australians not meeting the <a href="https://www.who.int/dietphysicalactivity/factsheet_adults/en/">WHO recommended guidelines</a> of accumulating 150 minutes of exercise per week, encouraging regular physical activity continues to be a pervasive public health message. </p>
<p>In terms of assessing risk, an exercise pre-screening assessment with an <a href="https://www.essa.org.au/find-aep">ESSA-qualified exercise specialist</a> will be able to assess and mitigate the risk of exercise participation.</p>
<h2>Exercise intensity: what happens when we go ‘all out’</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/266268/original/file-20190328-139356-l7v7dr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/266268/original/file-20190328-139356-l7v7dr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/266268/original/file-20190328-139356-l7v7dr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/266268/original/file-20190328-139356-l7v7dr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/266268/original/file-20190328-139356-l7v7dr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/266268/original/file-20190328-139356-l7v7dr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/266268/original/file-20190328-139356-l7v7dr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/266268/original/file-20190328-139356-l7v7dr.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>
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<span class="caption">Exercising at your maximal heart rate is not necessary to achieve cardiovascular health benefits.</span>
<span class="attribution"><span class="source">Unsplash</span></span>
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<p>Muscle cells require two key ingredients to function: fuel (glucose) and oxygen.</p>
<p>Muscles rely heavily on blood vessels to deliver the necessary nutrients and oxygen around the body, and also to remove by-products such as carbon dioxide.</p>
<p>The more muscles used in exercise, the more blood is distributed towards the active tissues.</p>
<p>When the intensity of the exercise is particularly high, the muscles start to produce another by-product called lactate. </p>
<p>Cells can also use lactate as a fuel although if production rate exceeds metabolism, lactate starts to accumulate and can interfere with cellular function. </p>
<p>The point at which this by-product starts to accumulate is termed the “lactate threshold”. </p>
<p>Any exercise intensity that can be comfortably sustained is usually below this threshold, and will have an accompanying heart rate. As it is much easier to measure heart rate than lactate production, heart rate can be used as a surrogate measure of exercise intensity.</p>
<h2>What is the best exercise for heart rate?</h2>
<p>While <a href="https://en.wikipedia.org/wiki/High-intensity_interval_training">interval-style</a> exercise training is a popular choice for people who are time-poor, the intermittent nature of the exercise means heart rate will fluctuate, providing <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4657417/">not much more benefit</a> than traditional steady-state exercise. </p>
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Read more:
<a href="https://theconversation.com/health-check-high-intensity-micro-workouts-vs-traditional-regimes-18617">Health Check: high-intensity micro workouts vs traditional regimes</a>
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<p>From a scientific perspective, athletes typically use heart-rate ranges to train at specific intensities during aerobic exercise, like cycling or long-distance running.</p>
<p>Exercising at certain intensities are known to elicit adaptive responses from the body, for example, exercising at or below the lactate threshold. </p>
<p>These intensities are called training zones and are expressed relative to HRmax. For instance, a light aerobic training session would be prescribed below 75% HRmax, while training at threshold (around 95% HRmax) will induce physiological change.</p>
<p>Overall, some exercise is better than no exercise for your cardiovascular health. Accumulating 150 minutes of exercise per week is the minimum requirement for health benefit. Exercising at your maximal heart rate is not necessary to achieve these benefits. Athletes can use training zones, relative to HRmax, to achieve optimal adaptation and enhance endurance performance.</p><img src="https://counter.theconversation.com/content/107963/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Angela Spence is affiliated with Exercise and Sports Science Australia (ESSA). </span></em></p><p class="fine-print"><em><span>Dr Carly Brade is affiliated with Exercise and Sports Science Australia (ESSA).</span></em></p>Exercising at your maximal heart rate isn’t always effective. Training smarter, not harder, will make you fitter.Angela Spence, Senior Lecturer in Exercise Physiology (BSc, PhD), Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/954402018-05-06T20:15:11Z2018-05-06T20:15:11ZEvery cancer patient should be prescribed exercise medicine<figure><img src="https://images.theconversation.com/files/217244/original/file-20180502-153873-1jx9usw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Most doctors and nurses agree exercise is beneficial but don’t routinely prescribe exercise as part of their patients' cancer treatment plan.</span> <span class="attribution"><span class="source">Photo credit: Exercise Oncology Team at Australian Catholic University</span></span></figcaption></figure><p>Every <a href="https://canceraustralia.gov.au/affected-cancer/what-cancer/cancer-australia-statistics">four minutes</a> someone in Australia is diagnosed with cancer. Only one in ten of those diagnosed will exercise enough during and after their treatment. But every one of those patients <a href="https://www.ncbi.nlm.nih.gov/pubmed/28453622">would benefit from exercise</a>.</p>
<p>I’m part of Australia’s peak body representing health professionals who treat people with cancer, the <a href="https://www.cosa.org.au/">Clinical Oncology Society of Australia</a>. Today we’re joining 25 other cancer organisations to <a href="https://www.cosa.org.au/publications/position-statements.aspx">call for exercise to be prescribed</a> to all cancer patients as part of routine cancer care.</p>
<p>Published today in the <a href="https://www.mja.com.au/journal/2018/209/6/clinical-oncology-society-australia-position-statement-exercise-cancer-care">Medical Journal of Australia</a>, our plan is to incorporate exercise alongside surgery, chemotherapy and radiotherapy to help counteract the negative effects of cancer and its treatment. </p>
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Read more:
<a href="https://theconversation.com/why-exercise-should-be-added-to-cancer-treatment-plans-12288">Why exercise should be added to cancer treatment plans</a>
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<h2>What are we calling for?</h2>
<p>Historically the advice to cancer patients was to rest and avoid activity. We now know this advice may be harmful to patients, and every person with cancer would benefit from exercise medicine. </p>
<p>Most doctors and nurses agree exercise is beneficial but don’t routinely prescribe exercise as part of their patients’ cancer treatment plan. </p>
<p>It is our position that all health professionals involved in the care of people with cancer should:</p>
<ol>
<li>view and discuss exercise as a standard part of the cancer treatment plan</li>
<li>recommend people with cancer adhere to exercise guidelines</li>
<li>refer patients to an exercise physiologist or physiotherapist with experience in cancer care.</li>
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<h2>Why prescribe exercise?</h2>
<p>Cancer patients who exercise regularly experience fewer and less severe side effects from treatments. They also have a lower relative risk of <a href="https://www.ncbi.nlm.nih.gov/pubmed/27407093">cancer recurrence</a> and a lower relative risk of <a href="https://www.ncbi.nlm.nih.gov/pubmed/26385207">dying from their cancer</a>.</p>
<p>If the effects of exercise could be encapsulated in a pill, it would be prescribed to every cancer patient worldwide and viewed as a major breakthrough in cancer treatment. If we had a pill called exercise it would be demanded by cancer patients, prescribed by every cancer specialist, and subsidised by government.</p>
<p>Cancer and its treatment can have a devastating effect on people’s lives, causing serious health issues that compromise their physical and mental well-being. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/xIQh4fUZkJs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Here’s why exercise is a new contender in the fight against cancer. TEDxPerth.</span></figcaption>
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<p>Research shows exercise can help cancer patients tolerate aggressive <a href="https://www.ncbi.nlm.nih.gov/pubmed/17785708">treatments</a>, minimise the <a href="https://www.ncbi.nlm.nih.gov/pubmed/28453622">physical declines</a> caused by cancer, counteract <a href="https://www.ncbi.nlm.nih.gov/pubmed/28253393">cancer-related fatigue</a>, relieve <a href="https://www.ncbi.nlm.nih.gov/pubmed/22068286">mental distress</a> and improve <a href="https://www.ncbi.nlm.nih.gov/pubmed/22895974">quality of life</a>. </p>
<p>When appropriately prescribed and monitored, exercise is <a href="https://www.ncbi.nlm.nih.gov/pubmed/20559064">safe</a> for people with cancer and the risk of complications is relatively low.</p>
<p>Implementing exercise medicine as part of routine cancer care not only has the potential to change people’s lives but to also save money. People with cancer who exercise have <a href="https://www.ncbi.nlm.nih.gov/pubmed/29527464">lower medical expenses</a> and spend <a href="https://www.ncbi.nlm.nih.gov/pubmed/22081271">less time away from work</a>.</p>
<h2>What exactly should be prescribed?</h2>
<p>Exercise specialists can prescribe exercise in a similar way that doctors prescribe medications; by knowing how cancer impacts our health, and understanding how certain exercises improve the structure and function of the body’s systems.</p>
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Read more:
<a href="https://theconversation.com/strength-training-can-have-unique-health-benefits-and-it-doesnt-have-to-happen-in-a-gym-84904">Strength training can have unique health benefits, and it doesn't have to happen in a gym</a>
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<hr>
<p>These individualised programs involve specific types of exercises, performed at precise intensities and volumes based on a mechanism of action and dosage needed to counteract the negative effects of cancer.</p>
<p>The <a href="https://www.ncbi.nlm.nih.gov/pubmed/20559064">evidence-based guidelines</a> recommend people with cancer be as physically active as their current ability and conditions allow. For significant health benefits, they should aim for:</p>
<ol>
<li><p>at least 150 minutes of moderate intensity aerobic exercise weekly (such as walking, jogging, cycling, swimming)</p></li>
<li><p>two to three resistance exercise session each week involving moderate to vigorous intensity exercises targeting the major muscle groups (such as weight lifting).</p></li>
</ol>
<p>These recommendations should be tailored to the individual’s abilities to minimise the risk of complications and maximise the benefits. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/217749/original/file-20180504-166881-v0xzrl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/217749/original/file-20180504-166881-v0xzrl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/217749/original/file-20180504-166881-v0xzrl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=319&fit=crop&dpr=1 600w, https://images.theconversation.com/files/217749/original/file-20180504-166881-v0xzrl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=319&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/217749/original/file-20180504-166881-v0xzrl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=319&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/217749/original/file-20180504-166881-v0xzrl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=401&fit=crop&dpr=1 754w, https://images.theconversation.com/files/217749/original/file-20180504-166881-v0xzrl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=401&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/217749/original/file-20180504-166881-v0xzrl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=401&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Exercise is safe for people with cancer and can be tailored for the individual.</span>
<span class="attribution"><span class="source">Photo Credit: Exercise Oncology Team at Australian Catholic University</span></span>
</figcaption>
</figure>
<h2>How will patients fill the prescription?</h2>
<p>Getting this much exercise may seem out of reach for many people with cancer. But exercise specialists who have experience in cancer care can help. They’ll design an individual program based on the patient’s disease, how they’ve responded to treatment and the anticipated trajectory of their health status.</p>
<p>Online directories can help find <a href="https://www.essa.org.au/find-aep/">accredited exercise physiologists</a> and <a href="https://choose.physio/">physiotherapists</a> practising nearby. These services are eligible for subsidies through Medicare and private health insurance.</p>
<p>Or patients can opt for structured <a href="http://www.exmedcancer.org.au/">cancer-specific exercise medicine programs</a> such as EX-MED Cancer, which I lead. Such programs are designed to maximise the safety and effectiveness of exercise medicine for cancer patients.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-prescription-for-better-health-exercise-after-prostate-cancer-40223">A prescription for better health: exercise after prostate cancer</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/95440/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Prue Cormie is the Chair of the Exercise and Cancer Group within the Clinical Oncology Society of Australia and leads the Exercise and Sports Science Australia Cancer Special Interest Group. She is a Principal Research Fellow at Australian Catholic University and holds honorary clinical exercise physiologist positions at Peter McCallum Cancer Centre, Austin Health (Olivia Newton-John Cancer Wellness and Research Centre) and Royal Melbourne Hospital. Prue Cormie receives funding from NHMRC, Cancer Australia, Prostate Cancer Foundation of Australia, National Breast Cancer Foundation, Cancer Councils and the Victorian Government.
</span></em></p>Historically the advice to cancer patients was to rest and avoid activity. We now know this advice may be harmful to patients, and that every person with cancer would benefit from exercise medicine.Prue Cormie, Principal Research Fellow in Exercise & Cancer, Australian Catholic UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/923662018-02-26T11:57:04Z2018-02-26T11:57:04ZCan coffee improve your workout? The science of caffeine and exercise<figure><img src="https://images.theconversation.com/files/207827/original/file-20180226-120971-1b6j9ij.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/resting-runner-260897984?src=XTj1Xdt-nA15eRNsMggkmg-1-1">Shutterstock</a></span></figcaption></figure><p>Caffeine is one of the most researched substances reported to help athletes perform better and train longer and harder. As a result, professional and amateur sportspeople often take it as a performance-enhancing “ergogenic” aids for a wide range of activities. These include intermittent exercise such as football and racket sports, endurance exercise such as running and cycling, and resistance exercise such as weightlifting.</p>
<p>But while most research looks at the effects of pure caffeine consumed as tablets with water, in the real world most people get their caffeine from coffee, energy drinks or other products like special gels or <a href="https://link.springer.com/article/10.1007/s40279-017-0848-2">chewing gum</a>. So will drinking a cup of joe before your workout actually make a difference? The answer could depend as much on your genes as what kind of coffee you’re drinking.</p>
<p><a href="https://jissn.biomedcentral.com/articles/10.1186/1550-2783-7-5">Scientists think</a> caffeine affects the body chemical adenosine, which normally promotes sleep and suppresses arousal. Caffeine ties up the receptors in the brain that detect adenosine and so makes it more alert.</p>
<p>But it may also increase stimulation of the central nervous system, making exercise seem like it involves less effort and pain. In high-intensity activities such as resistance training or sprinting, it may increase the number of fibres used in muscle contractions, meaning movements can be more frequent and forceful. </p>
<h2>Faster, higher, stronger</h2>
<p>Research has shown that pure caffeine can help endurance athletes <a href="https://link.springer.com/article/10.1007/s40279-014-0257-8">run faster</a> and <a href="http://www.mdpi.com/2072-6643/7/7/5219/htm">cycle for longer</a>. It can help footballers to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3279366/">sprint more often and over greater distances</a>, and basketball players to <a href="http://www.mdpi.com/2072-6643/9/9/1033/htm">jump higher</a>. It can help <a href="http://online.liebertpub.com/doi/abs/10.1089/jcr.2012.0019?journalCode=jcr">tennis players</a> and <a href="https://journals.lww.com/acsm-msse/fulltext/2016/01000/Effect_of_Caffeine_on_Golf_Performance_and_Fatigue.18.aspx">golfers</a> to hit the ball with greater accuracy. And it can help <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2876999/pdf/1550-2783-7-18.pdf">weightlifters lift more weight</a>.</p>
<p>The evidence for caffeine’s effects on sprinting is more mixed. Limited improvements <a href="http://www.mdpi.com/2075-4663/4/3/45">have been found</a> for events lasting under three minutes. But for races of around ten seconds,
caffeine can improve peak <a href="https://jissn.biomedcentral.com/articles/10.1186/1550-2783-12-S1-P57">power output, speed, and strength</a>.</p>
<p>An increasing number of studies have also shown that coffee can be used as an alternative to caffeine to <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0059561">improve cycling</a> and <a href="https://journals.humankinetics.com/doi/abs/10.1123/ijspp.2017-0456?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed&">competitive running</a> performance, and produce similar results similar to pure caffeine. In fact, coffee may even be more effective at <a href="https://journals.lww.com/nsca-jscr/Abstract/2016/10000/Effect_of_Coffee_and_Caffeine_Ingestion_on.27.aspx">improving resistance exercise than caffeine alone</a>. Similarly, drinking <a href="https://jissn.biomedcentral.com/articles/10.1186/1550-2783-10-1">energy drinks</a> containing caffeine before exercise can improve mental focus, alertness, anaerobic performance and endurance performance.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/207825/original/file-20180226-120971-lly7xa.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/207825/original/file-20180226-120971-lly7xa.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=330&fit=crop&dpr=1 600w, https://images.theconversation.com/files/207825/original/file-20180226-120971-lly7xa.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=330&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/207825/original/file-20180226-120971-lly7xa.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=330&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/207825/original/file-20180226-120971-lly7xa.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=414&fit=crop&dpr=1 754w, https://images.theconversation.com/files/207825/original/file-20180226-120971-lly7xa.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=414&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/207825/original/file-20180226-120971-lly7xa.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=414&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Total weight lifted when performing back squats to failure.</span>
<span class="attribution"><a class="source" href="https://journals.lww.com/nsca-jscr/Abstract/2016/10000/Effect_of_Coffee_and_Caffeine_Ingestion_on.27.aspx">Journal of Strength and Conditioning Research</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>But drinking coffee isn’t like taking a measured dose of caffeine. The amount of stimulant in a cup, and so how it affects you, will depend on the blend of coffee and how it is brewed. Studies have shown consuming either <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0059561">0.15g</a> or <a href="https://journals.humankinetics.com/doi/abs/10.1123/ijspp.2017-0456?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed">0.09g</a> of caffeinated coffee per kilogram of body weight can improve performance. So a dessert spoon of coffee granules rather than a traditional teaspoon is probably best. </p>
<p>It’s also worth bearing in mind that each piece of research shows caffeine improves athletic performance of a group of people as a whole. But we also know that <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5752738/pdf/40279_2017_Article_776.pdf">genetic factors</a> have a big influence on our responses to caffeine and not everyone reacts in the same way. This means consuming caffeine won’t necessarily improve your performance.</p>
<h2>Potential downsides</h2>
<p>In fact, you could end up feeling nauseated and jittery at a time when, if you are competing, you are already feeling anxious. And, as caffeine’s effects can linger for up to <a href="https://www.ncbi.nlm.nih.gov/books/NBK223808/">five hours</a>, taking it too late in the day could disrupt your sleep, which is a big factor in health and fitness in general. This means it’s important to practice with caffeine during training sessions or friendly fixtures before using it for an important event. </p>
<p>Some <a href="http://www.mysportscience.com/single-post/2017/06/18/Do-you-need-to-refrain-from-coffee-to-get-the-maximal-effect-of-caffeine">have also suggested</a> that you should abstain from caffeine in order to enjoy a better effect on your performance when you consume it for exercise. But maintaining your normal intake will prevent any <a href="https://theconversation.com/caffeine-withdrawal-drives-need-for-more-but-are-we-addicts-17380">possible withdrawal symptoms</a> and still provide benefits if caffeine is taken before exercise. Its effects peak between <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4898153/pdf/ictx-54-308.pdf">30 and 75 minutes after ingestion</a>.</p>
<p>Finally, it’s a a commonly held belief that caffeine is a diuretic that will lead to dehydration because it makes you produce more urine. But a <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0084154">number of studies</a> have shown that this isn’t the case with moderate amounts of coffee, cola or any other caffeinated beverage, which help keep you hydrated like any other drink.</p><img src="https://counter.theconversation.com/content/92366/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Neil Clarke receives funding from The Institute for Scientific Information on Coffee. </span></em></p>Drinking coffee before exercising could make you run faster and lift heavier - if you’ve the right genes.Neil Clarke, Principal Lecturer in Sport and Exercise Science at Coventry University, Coventry UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/915752018-02-14T03:27:08Z2018-02-14T03:27:08ZExplainer: how Winter Olympic athletes cope with the cold<figure><img src="https://images.theconversation.com/files/206311/original/file-20180213-175001-ba6dty.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Temperatures in Pyeongchang fall below -10℃ at night.</span> <span class="attribution"><span class="source">EPA/Filip Singer</span></span></figcaption></figure><p>The canvas of white currently fascinating many viewers of the Winter Olympics in Pyeongchang may seem totally foreign to those more used to watching sport played under the summer sun. It is grey and cold in the South Korean alpine town. Temperatures drop below <a href="https://www.accuweather.com/en/kr/pyeongchang-gun/223567/weather-forecast/223567">-10°C</a> at night.</p>
<p>Many might have questions about how elite athletes can perform to their best in such cold conditions. So, what’s happening to the body in the cold. What stresses does it experience? And what about injury?</p>
<h2>What happens to muscle in the cold?</h2>
<p>If human muscle is cooled by one degree, it <a href="https://www.ncbi.nlm.nih.gov/m/pubmed/1555556/">loses 2-5% of its performance</a>. A whole host of muscle properties <a href="https://www.ncbi.nlm.nih.gov/pubmed/525366">can be affected</a>, such as the time it takes a muscle to generate peak tension and then the time to relax from this peak.</p>
<p>Cold also disrupts the nervous impulses that control muscle through changes in activation patterns. So, there may be a delay in the sequence in which muscle activates to create and control movement. This <a href="https://www.ncbi.nlm.nih.gov/pubmed/21068679">equates to</a> about a 10-20% loss in vertical jump height and a reduction of up to 25% in peak muscle power.</p>
<p>For a landing, the limbs and joints become stiffer. This means much more force <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1896081/">gets absorbed</a> by a body’s trunk rather than in the lower limbs.</p>
<p>The losses in performance have been attributed to an increase in thickness of the fluid in muscle and joints, as well as the disruption of nervous input to muscle.</p>
<h2>How does this translate to sporting performance?</h2>
<p>In the longer events like cross-country and the longer downhill skiing runs, generating muscle heat isn’t as much of an issue. The events are long enough to allow elevated metabolism to generate enough body heat to offset the effects of the cold temperature. </p>
<p>But in the shorter events – like aerial skiing, <a href="https://theconversation.com/what-makes-a-winning-mogul-skier-like-matt-graham-91743">moguls</a>, ski jumping and many of the snowboarding events – getting a good warm-up and maintaining the heat close to the skin are imperative. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-makes-a-winning-mogul-skier-like-matt-graham-91743">What makes a winning mogul skier like Matt Graham?</a>
</strong>
</em>
</p>
<hr>
<p>Modern winter sport clothing relies on layering to maintain warmth. Athletes generally layer up with a next-to-skin garment, a mid-layer insulation, and an outer layer to protect from the wind and water. The next-to-skin layer is commonly worn to keep skin temperatures (and hopefully muscle temperatures) up. </p>
<p>Many athletes are now also using warming cuffs or pads which they remove just before their event. These self-warming devices fit over the next-to-skin garment and maintain the warmth around the large muscles and joints of the lower limbs. </p>
<p>But what if you don’t have the luxury of being an elite athlete?</p>
<p>The next time you hit the snow or exercise in the cold and don’t have the benefit of self-warming garments, take the time to warm up – thoroughly. This increases your metabolism and, in turn, warms the body from within. </p>
<p>Next, try to maintain the muscle temperature by wearing an insulated, next-to-skin garment that holds some of the heat generated. </p>
<p>And if you’re on a chairlift preparing to ski, remember that your muscles are cooling and losing some of their force and power-generating potential. Do a short secondary warm-up at the top of the run, or start up slow and build into the run.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/206313/original/file-20180214-174990-7zh9yk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/206313/original/file-20180214-174990-7zh9yk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=438&fit=crop&dpr=1 600w, https://images.theconversation.com/files/206313/original/file-20180214-174990-7zh9yk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=438&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/206313/original/file-20180214-174990-7zh9yk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=438&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/206313/original/file-20180214-174990-7zh9yk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=551&fit=crop&dpr=1 754w, https://images.theconversation.com/files/206313/original/file-20180214-174990-7zh9yk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=551&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/206313/original/file-20180214-174990-7zh9yk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=551&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Modern winter sport clothing relies on layering to maintain warmth.</span>
<span class="attribution"><span class="source">EPA/Filip Singer</span></span>
</figcaption>
</figure>
<h2>What about injury?</h2>
<p>The most popular winter sports – downhill skiing and snowboarding – have <a href="https://www.ncbi.nlm.nih.gov/pubmed/10352778">quite high injury rates</a>, mostly to the lower limbs. Improper techniques – especially landing techniques – <a href="https://www.ncbi.nlm.nih.gov/pubmed/19720537">have been linked</a> to many of these injuries.</p>
<p>Some studies <a href="https://www.astm.org/DIGITAL_LIBRARY/JOURNALS/JAI/PAGES/JAI101378.htm">have also linked</a> colder temperatures to increased injury rates. These studies suggest the increased injury rates are a result of changes in muscle performance coupled with the increased biomechanical demands of winter sport, such as having your feet bound to skis or a snowboard, performing sharp turns, and landing from a jump.</p>
<p>While watching the Pyeonchang Olympics on your couch, spare a thought for the changes in the body caused by the environment these athletes compete in. It fundamentally changes the body parts they rely on to carve, flip, twist, turn, slide, grab and generally shred up the Games’ white canvas.</p><img src="https://counter.theconversation.com/content/91575/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kevin Netto works for Curtin University. He receives funding from government and non-government organisations. </span></em></p>Here’s how athletes at the Winter Olympics are able to perform in extreme cold.Kevin Netto, Associate Professor, School of Physiotherapy and Exercise Science, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/753062017-05-05T01:53:37Z2017-05-05T01:53:37ZBeware the hype – springy soles won’t make you run much faster<figure><img src="https://images.theconversation.com/files/166241/original/file-20170421-12645-18gej98.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Springy soles, stiffer shoes, lightweight materials. When does shoe design give some runners an unfair advantage?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/544254466?src=ouwhewYFWf9JXeqj-kg3ig-1-45&size=medium_jpg">from www.shutterstock.com</a></span></figcaption></figure><p>Most runners believe a good pair of running shoes is worth the investment. But advances in running shoe technology have <a href="https://www.nytimes.com/2017/03/08/sports/nikes-vivid-shoes-and-the-gray-area-of-performance-enhancement.html?_r=0">sparked debate</a> about whether shoes help you run faster.</p>
<p>Can they really allow marathon runners to break the <a href="https://link.springer.com/article/10.1007%2Fs40279-017-0708-0">elusive two-hour barrier</a>, a challenge set to take place in Italy <a href="http://www.runnersworld.com/2-hour-marathon/how-to-watch-saturdays-sub-2-marathon-attempt">this weekend</a>? Or can newer shoes help you improve your personal best? </p>
<p>If they do, can we class these shoes as “performance enhancing” technologies that give runners an unfair advantage?</p>
<h2>Light shoes, better performance</h2>
<p>The weight of your running shoes can have a <a href="https://dx.doi.org/10.1007/s40279-014-0283-6">significant impact</a> on running performance. As shoes get heavier, muscles use more energy to move your feet, causing you to fatigue earlier, reducing your running performance.</p>
<p>Advances in materials technology have allowed running shoes to get lighter and lighter. Premium running shoes weigh on average 250 to 340 grams each, while the controversial <a href="http://news.nike.com/news/nike-zoom-vaporfly-elite">Nike Zoom Vaporfly Elite</a> tips the scales at just 184 grams.</p>
<p>If shoe weight is so important, why not <a href="https://theconversation.com/mondays-medical-myth-run-barefoot-to-prevent-injuries-7901">run barefoot</a>? Running barefoot requires energy to be absorbed by the muscles of the legs and feet when the foot hits the ground. Shoe cushioning can alleviate some of that. However, adding cushioning also increases shoe weight. So, there is a trade-off between the benefit of cushioning and the detrimental effects of added weight.</p>
<p>A <a href="http://journals.lww.com/acsm-msse/pages/articleviewer.aspx?year=2014&issue=02000&article=00015&type=abstract">recent study</a> found running in shoes each weighing 211 grams resulted in the same energy consumed for a given running distance (called <a href="https://en.wikipedia.org/wiki/Running_economy">running economy</a>) as running barefoot. And running barefoot on a treadmill, that provides the same cushioning as shoes (without adding weight to the feet), produced a small (~1.6%) improvement in running economy. </p>
<p>So the ideal would be to provide enough cushioning with as little weight as possible for the best running performance.</p>
<h2>Springy shoes, the jury’s out</h2>
<p>Reducing muscular effort at impact through shoe cushioning can be beneficial. But traditional running shoes lose energy with every step (converted mainly to heat). So, this energy must be replaced, through muscular contraction, to propel the runner into the next step and prevent a drop in speed.</p>
<p>In fact, cushioned shoes <a href="http://rsif.royalsocietypublishing.org/content/13/119/20160174">increase activation</a> of foot and leg muscles during push-off, compared to barefoot running. So the benefit of cushioning during impact may be offset by the increase in muscular effort needed to push off.</p>
<p>What if we could get back the energy lost at impact? Recent developments in running shoe design have focused on developing lightweight cushioning materials that act like springs to store energy from foot impact and return it to help power push off. In theory, this could reduce the muscular effort required to both absorb impact and power push-off and potentially <a href="http://jap.physiology.org/content/92/2/469">improve running economy</a>. </p>
<p>But there are complications we must consider before “springing” to a conclusion.</p>
<p>Springs only return energy they absorb when the shoe hits the ground. Springs cannot generate the <em>extra</em> energy needed to run uphill or accelerate. So muscles must still do this extra work and we do not yet know how a spring influences their ability to do this. This may potentially affect how efficiently you run uphill, downhill, accelerate or slow down.</p>
<h2>Stiff shoes help, but not too stiff</h2>
<p>The way the foot moves is also important. Our toe joints naturally bend when we push off, which dissipates some of the energy added by calf muscle contraction.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/165190/original/image-20170413-25898-145hwo3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/165190/original/image-20170413-25898-145hwo3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/165190/original/image-20170413-25898-145hwo3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/165190/original/image-20170413-25898-145hwo3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/165190/original/image-20170413-25898-145hwo3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/165190/original/image-20170413-25898-145hwo3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/165190/original/image-20170413-25898-145hwo3.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">High speed x-ray of running foot during push-off, when the toes bend and absorb energy. A hypothetical carbon insole is shown, which should theoretically reduce how much the toes bend and therefore reduce energy lost.</span>
<span class="attribution"><span class="source">Author provided, with Mike Rainbow, Susan De'Andrea and Nicolai Konow.</span></span>
</figcaption>
</figure>
<p>Reducing the amount the toes bend by making shoes stiffer can reduce the amount of energy lost. Stiffer soled shoes <a href="http://journals.lww.com/acsm-msse/pages/articleviewer.aspx?year=2006&issue=03000&article=00023&type=abstract">can improve running economy</a>, but only if the bending stiffness is <a href="http://www.jbiomech.com/article/S0021-9290(17)30015-5/abstract">optimised</a> for the specific athlete.</p>
<p>Too stiff and the calf muscles have to work too hard to produce the required forces to rotate the ankle; too soft and the benefit becomes trivial. </p>
<p>So it is not surprising shoes <a href="http://www.runningshoesguru.com/2017/03/nike-zoom-vaporfly-elite-the-shoe-of-breaking2-you-cant-buy/">Nike is preparing</a> for running marathons in under two hours have carbon fibre insoles where the bending stiffness is “tuned” for each runner.</p>
<p>The optimal stiffness of a shoe sole also varies depending on factors like the runner’s weight, leg length and strength. But a bigger design problem is that the optimal bending stiffness also varies with constantly changing factors.</p>
<p>Running at different speeds means we must change how we activate our muscles. But a simple spring, such as the <a href="https://www.scientificamerican.com/article/blade-runners-do-high-tech-prostheses-give-runners-an-unfair-advantage/">carbon fibre blade</a>, cannot change its stiffness for different speeds. </p>
<p>Even if we could tune shoe stiffness as we ran, this wouldn’t help with the added effort required to run uphill or accelerate.</p>
<h2>Are shoes ‘performance enhancing’ devices?</h2>
<p>Advances in shoe technology have the potential to improve running economy. At most, it is estimated this might make a difference of <a href="https://link.springer.com/article/10.1007%2Fs40279-017-0708-0">up to 2% in running economy</a> when running on a flat course, in ideal conditions.</p>
<p>For professional runners, we don’t think the latest improvements in design provides an “unfair” advantage because the shoes do not give runners extra energy; they only help preserve energy our muscles generate and are likely to require precise conditions to be effective.</p>
<p>While recreational runners may get a small performance benefit from lighter, better cushioned or slightly springy shoes, they would be better off increasing their fitness, and making sure their next shoes are comfortable and fit to reduce the chance of injury.</p><img src="https://counter.theconversation.com/content/75306/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Glen Lichtwark has received research funding from Asics Oceania to conduct footwear and running related research. He receives funding from the Australian Research Council (ARC), Cerebral Palsy Alliance and Cerebral Palsy International Research Foundation. He currently holds an ARC Linkage project in collaboration with the Australian Sports Commission. He is a council member with the International Society of Biomechanics</span></em></p><p class="fine-print"><em><span>Dominic Farris receives funding from the Australian Research Council (ARC) including a current ARC Linkage Project in collaboration with the Australian Sports Commission. He has also applied for ARC funding in collaboration with Asics Oceania to research foot and footwear biomechanics. He is a member of the International Society of Biomechanics. </span></em></p><p class="fine-print"><em><span>Luke A Kelly has received funding from Asics Oceania to conduct footwear and running related research. He receives funding from the Australian Research Council (ARC) and the National Health & Medical Research Council of Australia. He is a member of the scientific committee for Sports Medicine Australia.</span></em></p>Running shoes with springs in the soles have been touted as the next big thing in shoe design. But they won’t turn a weekend warrior into an Olympian.Glen Lichtwark, A/Prof in Exercise and Sport Science, The University of QueenslandDominic Farris, Research fellow, The University of QueenslandLuke A Kelly, Research Fellow, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/640432016-08-30T17:14:26Z2016-08-30T17:14:26ZHow the science of sports bras keeps women with larger breasts in the running<figure><img src="https://images.theconversation.com/files/135927/original/image-20160830-28253-12ebo5m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Kitted-out for sport.</span> <span class="attribution"><a class="source" href="https://pixabay.com/en/sports-bra-sport-bra-person-woman-274947/">Hans</a></span></figcaption></figure><p>British breasts are getting bigger, with <a href="http://www.dailymail.co.uk/femail/article-3233642/Average-bra-size-rises-36C-36DD-women-Cheshire-Manchester-boasting-largest-assets.html">an annual survey</a> indicating the average woman’s bra size has increased from a 36C to a 36DD – an increase in mass of around 430g. Research has shown that having larger breasts can <a href="http://www.ncbi.nlm.nih.gov/pubmed/24905581">put some women off participating in sports or exercise</a> and even <a href="http://www.tandfonline.com/doi/full/10.1080/17461391.2016.1200674">compromise sports performance</a>.</p>
<p>Sports bras are extremely important for women in competitive sports, but they’re also of significant benefit for all women who exercise. Compared to typical bras, today’s sports bras are the products of considerable scientific and technological research. Sports bra design and innovation has moved on greatly from the first general exercise bra developed by <a href="http://greatist.com/discover/sports-bra-history">Lisa Lindahl and Polly Smith in 1977</a>, which was in fact two jockstraps sewed together. </p>
<p>Recent developments include seamless knitting, and even tiny sensors and built-in actuators that alter the level of support the bra provides as required. Some sports bras today contain nanostructured textile sensors that <a href="https://sportsbrasts112.wordpress.com/sports-bra-technology/">communicate with your smart phone to monitor your cardiac health</a>, and even help to detect breast cancers.</p>
<p>During exercise, a woman’s torso moves in many different directions at different speeds. Since breasts contain no muscle and have limited internal support, they are essentially a mass of soft tissue that moves independently of, but is driven by, the motion of the torso. It’s this movement that sports bras and other support clothing works to reduce, altering the underlying mechanics to minimise the breasts’ motion independent of the rest of the body. This can minimise discomfort or pain, and even improve sports performance. It’s been shown that over a distance of 5km a sports bra can improve running technique, <a href="http://www.sciencedirect.com/science/article/pii/S0167945715000925">making it more economical</a> compared to an everyday bra. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/135924/original/image-20160830-28226-1m1gtk8.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/135924/original/image-20160830-28226-1m1gtk8.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=319&fit=crop&dpr=1 600w, https://images.theconversation.com/files/135924/original/image-20160830-28226-1m1gtk8.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=319&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/135924/original/image-20160830-28226-1m1gtk8.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=319&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/135924/original/image-20160830-28226-1m1gtk8.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=401&fit=crop&dpr=1 754w, https://images.theconversation.com/files/135924/original/image-20160830-28226-1m1gtk8.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=401&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/135924/original/image-20160830-28226-1m1gtk8.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=401&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sports bras using the encapsulation (left) and compression (right) methods to reduce movement.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Encapsulation_and_compression_sports_bras.gif">Mvtver</a></span>
</figcaption>
</figure>
<p>Of course, the demands placed on a sports bra increase with breast size, but larger breasts place greater demands on the body, too. Many women with larger breasts suffer from a sore back and shoulders, for example. A greater mass on the front of the body places additional strain on the posterior chain – the muscles that run down the back of the body that are key to correct posture. If these muscles have to work harder, this increased effort will require more energy.</p>
<p>For sportswomen, this essentially means carrying additional body mass that offers only a performance penalty rather than any gain. In sports that require pound-for-pound strength and whole body locomotion such as gymnastics, athletics or many field sports, women with larger breasts may be at a slight disadvantage. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/135925/original/image-20160830-28249-1qstl6z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/135925/original/image-20160830-28249-1qstl6z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/135925/original/image-20160830-28249-1qstl6z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/135925/original/image-20160830-28249-1qstl6z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/135925/original/image-20160830-28249-1qstl6z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/135925/original/image-20160830-28249-1qstl6z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/135925/original/image-20160830-28249-1qstl6z.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">Simona Halep at Open GDF Suez in 2010, after her breast reduction surgery.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Simona_Halep_at_Open_GDF_Suez_2010.jpg">Romain Dauphin-Meunier</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>However, there are limitations to what a sports bra can do. Some elite sportswomen have gone to more extreme lengths to reduce their breast size to improve performance. In 2009, Romanian tennis player Simona Halep had breast reduction surgery to go from a 34DD to 34C to help improve her reaction time and speed. Her worldwide ranking, previously below 450, improved such that by 2014 she was <a href="http://www.dailymail.co.uk/news/article-2665341/Win-bust-Tennis-star-breast-reduction-surgery-help-game-number-three-seed-Wimbledon.html">seeded third at Wimbledon</a>. Her tennis coach commented that “her strokes are less restricted now that those obstacles have been reduced”. </p>
<p>Australian athlete Jana Rawlinson, winner of the 400m hurdles at the 2007 World Championships, revealed that she <a href="http://www.dailymail.co.uk/femail/article-1281502/Teen-tennis-star-Simona-Halep-breast-reduction-surgery-boost-game.html">had breast implants removed</a> to improve her chances at the 2012 Olympics. Indeed, according to American Society for Aesthetic Plastic Surgery’s statistics, more than <a href="http://www.smartbeautyguide.com/procedures/breast/breast-reduction">100,000 women had breast reduction surgeries last year</a>, some of whom may well have made the decision due to playing sports.</p>
<p>Of course, having larger breasts doesn’t rule women out of playing sports or from Olympic-level competition, as there are many attributes both physical and psychological that contribute to sporting success. But wearing proper sports bras, regardless of breast size, has been shown again and again to provide the support required to hold breasts steady and reduce or eliminate any pain women may experience. All athletes need support, and a good sports bra is an important part of it.</p><img src="https://counter.theconversation.com/content/64043/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Mills 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>Sports bras can help elite athletes compete to their best, but also should be considered as an important piece of kit by all women who exercise.Chris Mills, Principal Lecturer in Biomechanics, University of PortsmouthLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/563452016-04-11T04:28:32Z2016-04-11T04:28:32ZHealth Check: does sex count as exercise?<figure><img src="https://images.theconversation.com/files/117805/original/image-20160407-10027-4z5u2f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The physiological response to sex is similar to that of exercise.</span> <span class="attribution"><span class="source">from shutterstock.com</span></span></figcaption></figure><p>Sex isn’t only a pleasurable experience with some <a href="http://www.mirror.co.uk/lifestyle/health/sex-better-exercise-going-jog-3090856">reports claiming</a> the act also has health benefits that can be compared to those of exercise.</p>
<p>In fact, the physiological response to sex is similar to that of exercise. Landmark studies in the 1960s showed people having sex had an <a href="https://books.google.com.au/books/about/Human_Sexual_Response.html?id=NexqAAAAMAAJ">increase in their respiratory rate</a>, heart rate and blood pressure.</p>
<p>These are all signs the body is working at an elevated rate, similar to that experienced during exercise. </p>
<p>More recently, these findings have been <a href="http://www.ncbi.nlm.nih.gov/pubmed/18082530">replicated by a number</a> of researchers using less obtrusive, miniaturised and wireless equipment, enabling more realistic results.</p>
<p>Again, they found a significant increase in markers of physiological stress, such as heart rate and blood pressure. Comparing this to what happens during exercise, they showed sexual activity elicits a moderate level of physical stress – up to 75% of maximal exercise. </p>
<p>But they also noticed these physiological stress levels were intermittent. Much of the average time of sexual activity recorded (33 minutes) was spent at lower stress levels. </p>
<p>A more recent study of young Canadian heterosexual couples <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0079342">showed a bout of sexual activity</a> was akin to moderate physical activity (such as brisk walking) when energy expenditure was measured. </p>
<h2>Sex is kind of like exercise</h2>
<p>So sex is exercise? Well yes and no. It depends on your definition of exercise. If you compare the two purely by the physiological change that occurs then yes, because sex elicits a change in human physiology akin to exercise. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/117928/original/image-20160408-23938-3lu5kc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/117928/original/image-20160408-23938-3lu5kc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=743&fit=crop&dpr=1 600w, https://images.theconversation.com/files/117928/original/image-20160408-23938-3lu5kc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=743&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/117928/original/image-20160408-23938-3lu5kc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=743&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/117928/original/image-20160408-23938-3lu5kc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=933&fit=crop&dpr=1 754w, https://images.theconversation.com/files/117928/original/image-20160408-23938-3lu5kc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=933&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/117928/original/image-20160408-23938-3lu5kc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=933&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sex elicits a similar physiological response to exercise.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>But if you believe exercise should change human physiology for the better, in the long term, then perhaps no. This is because, for most of us, sex isn’t sustained long enough nor occurs frequently enough for a true physiological change to happen in the long term. </p>
<p>Also, we haven’t really explored the other benefits of exercise and contrasted them with sex. For instance, muscular health is recognised as a major component of a person’s health. </p>
<p>We know lots about gaining muscular health through resistance training and other exercises. But does sex give enough of a workout to change muscular health? Well … I sense a research project in the pipeline. </p>
<p>The studies mentioned above also reported a distinct difference between responses in males and female participants. The reasons for this difference – whether men are more physically active during sex compared to women or whether different sexual positions place a greater demand on the human body – have yet to be explored.</p>
<p>What about masturbation? Increases in heart rate and systolic blood pressure <a href="http://www.sciencedirect.com/science/article/pii/S0306453099000499">have been reported</a> during masturbation. But both the level and duration of these increases weren’t as high or long as with intercourse.</p>
<p>Judging by measurements of heart rate, masturbation really only equates to light exercise, such as slow walking. </p>
<h2>How exercise affects sex and vice versa</h2>
<p>In many cases, exercise can also be helpful to sex. Research into pelvic floor exercises in women with pelvic pain, for instance, has shown they <a href="http://www.ncbi.nlm.nih.gov/pubmed/25401779">improve sexual function</a>. Women reported increased control, confidence, hightened sensation and less pain.</p>
<p>While in men, exercises that <a href="http://onlinelibrary.wiley.com/doi/10.1002/ca.22655/abstract">train the perineal muscles</a> in front of the anus help with premature ejaculation. </p>
<p>And what about how sex affects exercise? Should professional sportspeople, for instance, refrain from sex before a competition?</p>
<p>Not if they wait <a href="http://www.ncbi.nlm.nih.gov/pubmed/11125766">long enough after sex</a>. Sex has been shown to have no negative effect on sports performance but can have a negative effect on recovery if you compete within two hours of having it. This means athletes could take longer to recover from one bout of exercise to another.</p>
<p>So in answer to the question of whether sex is really exercise. Kind of. But you can test it out for yourself and see how you feel.</p><img src="https://counter.theconversation.com/content/56345/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kevin Netto 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>Sex can often be a pleasurable experience. But it also has benefits some reports have compared to those of exercise. So can sex really count as a workout?Kevin Netto, Associate Professor, Physiotherapy and Exercise Science, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/317292015-05-18T04:49:50Z2015-05-18T04:49:50ZHealth check: what’s the deal with electrolytes?<figure><img src="https://images.theconversation.com/files/81979/original/image-20150518-25437-1piibfz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sweat is made up of water and minerals that are collectively known as electrolytes. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/chrishunkeler/8049103309/">Chris Hunkeler/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Electrolytes are an important part of normal human function. The failure to maintain a normal balance of electrolytes can lead to dehydration and possibly heart and neurological problems.</p>
<p>When we’re physically active, either as a regular part of the day or when exercising, our bodies produce heat. So we start sweating to prevent overheating. Loss of water in this way can lead to dehydration, but failure to prevent overheating by sweating can result in dizziness, thirst, headaches, nausea, muscle spasms, cramps, fatigue and disorientation. </p>
<p>The human body can produce up to two litres of sweat in an hour, although this amount is highly dependent on environmental conditions as well as exercise intensity and duration. Sweat losses of this magnitude, which can amount to 2% of body weight, can significantly affect how the body functions at rest. And it can result in a significant <a href="http://www.ncbi.nlm.nih.gov/pubmed/17277604">decrease in performance during exercise</a>.</p>
<h2>Enter electrolytes</h2>
<p>Sweat is largely made up of water (the watery part of blood known as plasma) as well as important minerals including sodium, potassium, magnesium, chloride, calcium, bicarbonate, phosphate and sulphate. These minerals are collectively known as electrolytes and are essential for the normal function of our cells and organs. </p>
<p>Sodium is the most important electrolyte because it plays a key role in normal muscle and nerve function and preventing cramps, as well as in stimulating thirst, improving fluid absorption in the small intestine and helping fluid retention. </p>
<p>Other electrolytes also play key roles in normal physiological function. Calcium, for instance, helps co-ordinate muscle contraction. Low levels of potassium and magnesium are implicated in muscle cramps. Chloride, bicarbonate, phosphate and sulphate all contribute to maintaining pH balance and regulating fluid in and out of cells. </p>
<p>Traditionally, we just drank water to rehydrate, but <a href="http://www.ncbi.nlm.nih.gov/pubmed/1895359">research</a> published <a href="http://www.ncbi.nlm.nih.gov/pubmed/9694418">in the 1990s</a> showed that could be improved on when water had a small amount of glucose and a larger portion of sodium in it. This led to the creation of electrolyte-based rehydration drinks.</p>
<h2>Electrolyte drinks</h2>
<p>Electrolyte drinks are a simple but effective way of rehydrating. You can buy ready-made drinks as a practical way to replace the lost electrolytes, or you can purchase a tube of effervescent electrolyte tablets or tub of powder and simply mix with plain water. Alternatively, you can add a little bit of salt to your post-exercise meal as an economical alternative. </p>
<p>But the tablet and powder make a nice-tasting, scientifically formulated drink that quickly rehydrates. And it may be a better choice because many ready-made electrolyte drinks contain large amounts of sugar.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/81980/original/image-20150518-25403-13aeph2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/81980/original/image-20150518-25403-13aeph2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/81980/original/image-20150518-25403-13aeph2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/81980/original/image-20150518-25403-13aeph2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/81980/original/image-20150518-25403-13aeph2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/81980/original/image-20150518-25403-13aeph2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/81980/original/image-20150518-25403-13aeph2.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">
<figcaption>
<span class="caption">Sports drinks aim to replenish the sugars used during high-intensity exercise as well as electrolytes.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/cleanwalmart/374245972/">Clean Wal-Mart</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Typically known as “sports drinks”, these beverages have a different intention to just rehydrating. They aim to replenish the sugars used during high-intensity exercise. But most people who exercise don’t do so to the degree of intensity that justifies consuming sports drinks.</p>
<p>Electrolyte “only” drinks, that is, the tablets or powder you dissolve in water yourself, are calorie-free. So they’re a better option for people who are exercising to lose weight and are looking to rehydrate, or even people who don’t want to consume the added sugar. Sports drinks have been <a href="https://theconversation.com/health-check-whats-eating-your-teeth-37096">linked to serious dental erosion</a>.</p>
<h2>Who benefits?</h2>
<p>Everyone sweats during exercise – both incidental and planned – so electrolytes are good for anyone who wants to recover the water and electrolytes lost through sweat. That means anyone from recreational exercisers to elite athletes can consume electrolytes. The main thing to be mindful of is the sugar content of sports drinks. </p>
<p>When we exercise, our fluid and electrolyte requirements increase. So consuming at least half a litre of an electrolyte drink three to four hours before exercise, a quarter of a litre two hours prior to exercise and approximately the same every 20 to 30 minutes during exercise will <a href="http://www.ncbi.nlm.nih.gov/pubmed/17277604">ensure you stay hydrated</a>. </p>
<p>The most important thing to note is that everyone sweats at a different rate. A practical way to work out how much fluid you lose during exercise is simply to weigh yourself immediately before and after exercise. The difference will indicate how much you need to replace: for every one kilogram of body weight lost during exercise, you should consume a litre and half of an electrolyte drink.</p>
<p>If you’re particularly curious, you can compare your urine colour against a chart or have it assessed in terms of darkness. Darker yellow or brown urine indicates greater levels of dehydration. </p>
<p>Or you can simply drink to thirst – a strategy that’s just as effective as having a personalised hydration protocol! </p>
<p>Remember that the warmer it is, the more you will sweat, so you’ll need to drink more during the warmer months. Improving your daily hydration levels will support your exercise requirements and help you get and keep fit.</p><img src="https://counter.theconversation.com/content/31729/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jon Bartlett 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>Sports drinks claiming to contain electrolytes have innundated stores in recent years. So what are electrolytes? Are they good? How can we best get them?Jon Bartlett, Sport Science Research Fellow, Victoria UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/372862015-03-02T03:42:59Z2015-03-02T03:42:59ZHealth Check: how to exercise safely in the heat<figure><img src="https://images.theconversation.com/files/73121/original/image-20150226-1807-hzlmxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">If you're not regularly active, extreme exercise and exercise in extreme heat is unwise.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-239818048/stock-photo-tired-woman-runner-taking-a-rest-after-running-hard-in-countryside-road-sweaty-athlete-after.html?src=jQxMS54jYe8X9RUXRnMCdQ-3-127&ws=1">lzf/Shutterstock</a></span></figcaption></figure><p>Exercise alone can be hard, but exercising in the heat is a whole lot harder. Put simply, this is due to the balance between how much heat the body generates and how much it is capable of losing.</p>
<p>Human core body temperature typically remains around 36.5°C to 37°C, with small fluctuations across the day. Larger changes above 40°C can be dangerous. </p>
<p>Fortunately, humans are relatively well-adapted to dealing with the heat. One theory is that humans evolved a <a href="https://www.youtube.com/watch?v=826HMLoiE_o">survival advantage as hunters</a> because they could outlast animals that were less able to manage long periods of <a href="http://www.nature.com/nature/journal/v432/n7015/abs/nature03052.html">exertion under hot conditions</a>. </p>
<h2>How do we regulate our temperature?</h2>
<p><strong>1. Radiation:</strong> There are so many small blood vessels in the skin that, in total, they can receive up to 60% of output from the heart at rest. </p>
<p>As blood flows from the core of the body to the skin, opening of these small blood vessels allows more surface area for heat exchange with the environment. </p>
<p>Radiation of heat occurs when the surrounding environment is less hot than the skin surface. At rest in a cool environment, 60% of heat loss is by <a href="http://link.springer.com/article/10.1007/BF00596389">radiation</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/73139/original/image-20150226-1814-1fsca4t.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/73139/original/image-20150226-1814-1fsca4t.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=384&fit=crop&dpr=1 600w, https://images.theconversation.com/files/73139/original/image-20150226-1814-1fsca4t.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=384&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/73139/original/image-20150226-1814-1fsca4t.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=384&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/73139/original/image-20150226-1814-1fsca4t.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=482&fit=crop&dpr=1 754w, https://images.theconversation.com/files/73139/original/image-20150226-1814-1fsca4t.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=482&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/73139/original/image-20150226-1814-1fsca4t.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=482&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-177791000/stock-vector-vector-illustration-of-diagram-of-human-skin-anatomy.html?src=_xkOoBHTHcJ67yFbZbDW-A-1-1&ws=1">stockshoppe/Shutterstock</a></span>
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</figure>
<p><strong>2. Evaporation:</strong> As core temperature rises, sweat glands in the skin are activated, promoting heat loss via the combined processes of <a href="https://theconversation.com/want-to-keep-cool-on-hot-summer-days-heres-how-34489">convection, conduction and evaporation</a>. </p>
<p>These forms of heat exchange become more important as heat production rises (such as during exercise), and as the environment becomes hotter and radiation less effective.</p>
<h2>Why is it so hard to exercise in the heat?</h2>
<p>Muscles that are active during exercise demand more energy and, consequently, increased blood supply and delivery of oxygen. This means the heart has to work harder to re-circulate blood to the active muscles. </p>
<p>Exercising muscles also generate heat, as a by-product of chemical reactions inside cells. This increases core body temperature which, if not compensated for, can compromise the ongoing function of the central nervous system and/or muscle cells themselves. </p>
<p>To lose heat, blood needs to be sent to the small arteries under the skin surface, so that heat transfer can take place via radiation. Sweating alone is relatively ineffective if this re-distribution of blood does not occur concurrently. </p>
<p>So when exercise occurs under circumstances where heat loss is challenged (because the gradient between skin and environmental temperatures is narrow), more blood needs to be directed to the skin at the same time as this blood is needed in the muscles to increase workload. </p>
<p>A competition therefore develops between the skin and working muscles for the limited maximal blood flow that the heart can manage.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/73122/original/image-20150226-1819-l51osa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/73122/original/image-20150226-1819-l51osa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/73122/original/image-20150226-1819-l51osa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/73122/original/image-20150226-1819-l51osa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/73122/original/image-20150226-1819-l51osa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/73122/original/image-20150226-1819-l51osa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/73122/original/image-20150226-1819-l51osa.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">Acclimatisation can increase a person’s capacity to heat loss.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-201434165/stock-photo-man-fitness-runner-drinking-and-splashing-water-in-his-face-funny-image-of-handsome-male.html?src=jQxMS54jYe8X9RUXRnMCdQ-2-73&ws=1">Milles Studio/Shutterstock</a></span>
</figcaption>
</figure>
<p>Different theories explain fatigue (the point at which you cannot maintain exercise duration and/or intensity) as either the inability to sustain oxygen delivery to the muscle in the face of thermoregulatory demand, or an inability to control body and brain temperature during exercise in hot environments. </p>
<p>The causes of fatigue are of great interest to exercise scientists concerned with sport and workplace performance. We know that acclimation (the process of repeated exercise in hot conditions) can enhance an individual’s capacity for heat loss and, therefore, improve exercise performance and delay fatigue. </p>
<p>Several steps in the exercise and thermoregulatory chain are amenable to adaptations that improve performance, including enhanced <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3006409/">function</a> and <a href="http://www.ncbi.nlm.nih.gov/pubmed/21131471">structure</a> of the blood vessels, the function and size of the <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3240883/">heart</a> and even <a href="http://www.ncbi.nlm.nih.gov/pubmed/1798375">blood volume</a> itself.</p>
<h2>Who is at risk of heat stroke?</h2>
<p>Heat stroke is a serious illness and those most at risk include adults aged over 65 years, babies and young children, pregnant women, people with existing medical conditions and those on particular medications. Most obviously, those who already have heart problems are at particular risk. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/73137/original/image-20150226-1758-efnocd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/73137/original/image-20150226-1758-efnocd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/73137/original/image-20150226-1758-efnocd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/73137/original/image-20150226-1758-efnocd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/73137/original/image-20150226-1758-efnocd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/73137/original/image-20150226-1758-efnocd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/73137/original/image-20150226-1758-efnocd.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">Older people are at greater risk of heat-related illness.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-141240130/stock-photo-portrait-an-elderly-woman.html?src=cQBoG_PFJsn_PXbyX5_qpQ-1-133&ws=1">De Visu/Shutterstock</a></span>
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<p>Such is the <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC192832/">risk of heat illness</a> that 10,000 excess deaths occurred during a heatwave in Europe in 2003. </p>
<p>In the Australian summer of 2009, hot conditions in Victoria and South Australia were linked with higher rates of illness and more than 200 extra deaths than would normally occur, particularly among the elderly and those with heart disease.</p>
<p>Early signs of heat exhaustion can include dizziness, headache and nausea. More severe cases of heat stroke involve hot dry skin with (paradoxically) no sweating, confusion and fainting.</p>
<p>Sports Medicine Australia has produced a <a href="http://sma.org.au/wp-content/uploads/2009/05/hot-weather-guidelines-web-download-doc-2007.pdf">helpful guide</a> to performance of sport or exercise in hot weather, which details the risk and symptoms of heat illness. </p>
<h2>What’s the best way to deal with the heat?</h2>
<p>For professional athletes, exercising in warm conditions can improve performance and is sometimes essential to prepare for different environmental conditions, such as preparing for an Olympic games in a hot country. </p>
<p>Regardless, it’s important to take precautions to reduce the likelihood of heat illness by staying hydrated, wearing appropriate clothing and knowing your limits.</p>
<p>For people who don’t exercise regularly or those who are at increased risk of heat-related illness, avoid exercising in the heat, such as the middle of the day in summer or rooms with poor air circulation. </p>
<p>Instead, opt for a prescribed, gradual and incremental exercise program that improves your cardiovascular and thermoregulatory tolerance. Gradual and repeated heat exposure, even in the absence of exercise, may also be <a href="http://www.ncbi.nlm.nih.gov/pubmed/25705824">good for your health</a>. </p>
<p>The good news is that even exercise in normal or cool conditions will improve thermoregulatory capacity and resilience under hot conditions. But if it’s out of the ordinary for you, extreme exercise or exercise in extremes, is equally unwise.</p><img src="https://counter.theconversation.com/content/37286/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Howard Carter receives funding from the National Heart Foundation of Australia.</span></em></p><p class="fine-print"><em><span>Daniel Green receives funding from the Australian Research Council, National Heath and Medical Research Council, National Heart Foundation of Australia.</span></em></p>Exercise alone can be hard, but exercising in the heat is a whole lot harder. Put simply, this is due to the balance between how much heat the body generates and how much it is capable of losing.Howard Carter, Research Associate, School of Sports Science, Exercise and Health, The University of Western AustraliaDaniel Green, Winthrop Professor, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.