tag:theconversation.com,2011:/ca/topics/muscle-wasting-2408/articlesMuscle wasting – The Conversation2024-01-04T20:46:52Ztag:theconversation.com,2011:article/2188812024-01-04T20:46:52Z2024-01-04T20:46:52ZFor cancer patients, maintaining muscle is vital to health and treatment, but staying strong is complicated<figure><img src="https://images.theconversation.com/files/567306/original/file-20231222-19-bbnx0m.jpg?ixlib=rb-1.1.0&rect=308%2C44%2C7040%2C4638&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">With cachexia, a patient loses a significant amount of weight due to their disease, with considerable losses of muscle mass.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/for-cancer-patients-maintaining-muscle-is-vital-to-health-and-treatment-but-staying-strong-is-complicated" width="100%" height="400"></iframe>
<p>Nearly <a href="https://www.cancer.gov/about-cancer/treatment/research/cachexia">one-third of cancer patients die</a> from a side-effect you’ve likely never heard of: cancer cachexia. </p>
<p>With cachexia, a patient loses a significant amount of weight due to their disease, with considerable losses of muscle mass. Muscle plays essential roles in movement, exercise and metabolism. Simple things like walking up the stairs, doing laundry and taking a breath are only possible because of muscles.</p>
<p>Despite the significance of cachexia for cancer patients, there has been very little progress in treating the condition. </p>
<h2>What exactly is cancer cachexia?</h2>
<p>Cancer cachexia is an unintentional loss of body weight that mainly affects muscle. It is diagnosed when a cancer patient loses more than five per cent of their body weight over six months. For a 180-pound (82-kilogram) person, this would equate to nine pounds, or four kilograms, lost. </p>
<p>Skeletal muscle is a remarkable organ that can repair and rebuild itself regularly. Muscle experiences periods of breakdown and rebuilding every day. When we exercise, we induce muscle damage, that is then repaired, to make even stronger muscles. In a healthy person, this keeps muscle mass balanced and relatively unchanged day-to-day. However, in a condition like cachexia, <a href="https://doi.org/10.1152/japplphysiol.91375.2008">this system is no longer balanced</a>. </p>
<p>During cachexia, we see increases in the pathways responsible for muscle breakdown and decreases in the pathways responsible for <a href="https://doi.org/10.1152/japplphysiol.00622.2019">muscle rebuilding</a>. These changes result in gradual and consistent muscle tissue breakdown, resulting in muscle loss. This muscle loss also means lost strength and increased fatigue. Excessive muscle loss can eventually cause the heart and lungs to stop working properly, causing death.</p>
<p>Cancer cachexia is complex, and is likely caused by many factors working together. Inflammation from cancer or chemotherapy, reduced appetite and food intake, or even specific interactions between a tumour and muscle <a href="https://doi.org/10.1186/s13045-023-01454-0">could all play a role</a>.</p>
<h2>The impact of cachexia on patients</h2>
<figure class="align-center ">
<img alt="A grey-haired man with an IV in his arm and a younger woman in scrubs" src="https://images.theconversation.com/files/567308/original/file-20231222-21-4evj3f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/567308/original/file-20231222-21-4evj3f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567308/original/file-20231222-21-4evj3f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567308/original/file-20231222-21-4evj3f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567308/original/file-20231222-21-4evj3f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567308/original/file-20231222-21-4evj3f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567308/original/file-20231222-21-4evj3f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Cachexia can affect how chemotherapies work.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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</figure>
<p>Cancer cachexia can have a significant impact on a patient’s quality of life and prognosis. While muscle wasting is not typically painful, the general loss of strength, muscle function and, ultimately, independence can be jarring. </p>
<p>Many everyday tasks are impacted by loss of strength and increased fatigue. Activities like exercise, gardening, showering or getting dressed all grow increasingly difficult as muscle disappears. Cachexia can also influence how well certain chemotherapies work. Patients with cachexia tend to have <a href="https://doi.org/10.1200/EDBK_389942">lower treatment tolerances</a> than those of healthy body composition. </p>
<p>Emotionally, cachexia can be extremely difficult to manage. Cachexia patients report struggling with body image, loss of independence and becoming a <a href="https://doi.org/10.1007/s13539-014-0142-1">burden to their loved ones</a>. They also tend to have higher rates of <a href="http://dx.doi.org/10.1136/bmjspcare-2019-002176">anxiety and depression</a>.</p>
<h2>Treating cachexia</h2>
<p>Unfortunately, Canada lacks standardized options for treating patients with cancer cachexia. </p>
<p>Research suggests that treating cachexia should use a <a href="https://doi.org/10.1186/s13045-023-01454-0">multi-targeted approach</a>. Nutritional interventions are essential for combating cachexia and should be started as soon as possible with consultation from a registered dietitian. </p>
<figure class="align-center ">
<img alt="A seated woman lifting a small dumbbell with assistance from a woman in scrubs standing behind her" src="https://images.theconversation.com/files/567307/original/file-20231222-19-efnd63.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/567307/original/file-20231222-19-efnd63.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=446&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567307/original/file-20231222-19-efnd63.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=446&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567307/original/file-20231222-19-efnd63.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=446&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567307/original/file-20231222-19-efnd63.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=560&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567307/original/file-20231222-19-efnd63.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=560&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567307/original/file-20231222-19-efnd63.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=560&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Exercise could be a powerful tool to treat cachexia.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Exercise could be a very powerful tool to <a href="https://doi.org/10.3390/cancers14102512">treat cachexia</a>. A combination of aerobic and strength exercises is likely most beneficial. Exercise can also improve general quality of life and mental <a href="https://doi.org/10.1186/s12904-022-00948-x">health of cancer patients.</a>. It is important that any exercise interventions are accompanied by nutritional support and supervision, so that muscles have adequate material and energy to rebuild, and patients can have safe and adapted programs. </p>
<p>Studies on pharmacological compounds to treat cachexia have produced varied results, and many are still in early phase <a href="https://doi.org/10.%201200/JCO.20.00611">clinical trials</a>. While this is a promising area of research, patients cannot currently access cachexia-specific drugs outside of clinical trials.</p>
<h2>Diagnosing and detecting cachexia</h2>
<p>Perhaps the biggest limitation in treating cachexia is detecting it early enough to intervene. Diagnosing cachexia is largely based on weight-related measures. Unfortunately, many health-care professionals are not performing these basic diagnostic assessments. </p>
<p>An international study found that only about half of health-care professionals surveyed thought newly diagnosed cancer patients <a href="https://doi.org/10.1002/jcsm.13105">should be weighed</a>. Cachexia is likely underdiagnosed and, therefore, under-addressed among Canadians. </p>
<p>Further, using weight loss as the standard diagnostic criteria may not be an accurate or sensitive tool. Conditions like obesity may mask the detection of muscle loss when only weighing patients. Studies have also found that <a href="https://doi.org/10.1172/jci.insight.155147">strength</a> and <a href="https://doi.org/10.1152/japplphysiol.00622.2019">muscle integrity</a> changes are apparent before weight loss. </p>
<p>Integrating strength assessments as well as body composition scans across all points of the cancer journey could help capture the whole picture of cachexia development and progression. </p>
<h2>Where to go from here</h2>
<p>Cachexia has a massive impact on cancer outcomes and patient quality of life. The sooner it is detected, the better chance there is to manage it. Management should involve a multi-disciplinary team that can help with diet, exercise and psycho-social aspects of the condition.</p>
<p>Current research is focusing on developing medications that can specifically target the pathways of muscle wasting. It will likely be years before these reach the clinic, so early interventions with nutrition, exercise and regular monitoring are critical. More robust diagnostic criteria, such as imaging as well as strength and functional assessments, could help. </p>
<p>Cancer is a life-changing disease, and it’s important to ensure that patients can stay as strong as possible during the process. </p>
<p>Understanding cancer cachexia means prolonging both quantity and quality of life for Canadians.</p><img src="https://counter.theconversation.com/content/218881/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Meghan McCue receives funding from the Canadian Cancer Society and the Canadian Partnership Against Cancer. </span></em></p>Cachexia — significant loss of weight and muscle mass — has a massive impact on cancer outcomes and patient quality of life. The sooner it is detected, the better chance there is to manage it.Meghan McCue, PhD Candidate, Biomolecular Sciences, Laurentian UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2035622023-05-17T01:27:55Z2023-05-17T01:27:55ZAm I too old to build muscle? What science says about sarcopenia and building strength later in life<figure><img src="https://images.theconversation.com/files/525760/original/file-20230512-41125-9ts1je.jpg?ixlib=rb-1.1.0&rect=0%2C44%2C7360%2C4858&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Sarcopenia is the progressive and accelerated loss of muscle mass and strength as we age. </p>
<p>The term was coined in the 1980s, and the condition has been recognised as a disease for less <a href="https://onlinelibrary.wiley.com/doi/full/10.5694/mja2.50432">than a decade</a>, but the concept is as old as time: use it or lose it.</p>
<p>But what if you’re in your 60s, 70s, 80s or 90s? Is it “too late” to build muscle and fight sarcopenia? Here’s what the research says.</p>
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<a href="https://images.theconversation.com/files/525756/original/file-20230511-19-34yuj7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/525756/original/file-20230511-19-34yuj7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525756/original/file-20230511-19-34yuj7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525756/original/file-20230511-19-34yuj7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525756/original/file-20230511-19-34yuj7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525756/original/file-20230511-19-34yuj7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525756/original/file-20230511-19-34yuj7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525756/original/file-20230511-19-34yuj7.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">Exercise training during weight loss can also prevent bone loss.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-muscle-wasting-condition-sarcopenia-is-now-a-recognised-disease-but-we-can-all-protect-ourselves-119458">The muscle-wasting condition 'sarcopenia' is now a recognised disease. But we can all protect ourselves</a>
</strong>
</em>
</p>
<hr>
<h2>Sarcopenia isn’t just unfortunate. It’s dangerous</h2>
<p>All of us will start to gradually lose muscle from our mid-30s, but this loss accelerates in later years. For up to 30% of adults aged over 60, the declines are substantial enough to meet the <a href="https://onlinelibrary.wiley.com/doi/10.1002/jcsm.12783">definition for sarcopenia</a>.</p>
<p>Sarcopenia increases your risk of falls, fractures, hospitalisation, loss of independence and many other chronic diseases. </p>
<p>However, people who are active in early life and maintain this as they age can delay or prevent the <a href="https://onlinelibrary.wiley.com/doi/10.1002/jcsm.13218">onset of sarcopenia</a>.</p>
<p>The good news is it’s never too late to make a start, even if you are already experiencing the debilitating effects of sarcopenia. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525520/original/file-20230511-29-5201jv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/525520/original/file-20230511-29-5201jv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525520/original/file-20230511-29-5201jv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525520/original/file-20230511-29-5201jv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525520/original/file-20230511-29-5201jv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525520/original/file-20230511-29-5201jv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=492&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525520/original/file-20230511-29-5201jv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=492&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525520/original/file-20230511-29-5201jv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=492&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It’s never too late to make a start.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>What the science says</h2>
<p>Resistance training is the most effective way to build and strengthen muscle at all ages. That means things like:</p>
<ul>
<li><p>lifting free weights like dumbbells</p></li>
<li><p>using machine weights, like you find in a gym</p></li>
<li><p>using resistance bands</p></li>
<li><p>bodyweight exercises such as push-ups, squats, wall-sits or tricep dips.</p></li>
</ul>
<p>It’s OK to start with even very light weights, or do modified, easier versions of bodyweight exercises (for example, you might do a shallow squat rather than a deep one, or a push-up against a wall or windowsill instead of on the floor). Something is always better than nothing. </p>
<p>Aim to make the exercise harder over time. Lift progressively heavier weights or do increasingly harder versions of bodyweight or resistance band exercises. This is called progressive resistance training.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525565/original/file-20230511-27-1sxqpo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/525565/original/file-20230511-27-1sxqpo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525565/original/file-20230511-27-1sxqpo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525565/original/file-20230511-27-1sxqpo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525565/original/file-20230511-27-1sxqpo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525565/original/file-20230511-27-1sxqpo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525565/original/file-20230511-27-1sxqpo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525565/original/file-20230511-27-1sxqpo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Aim to make the exercise harder over time.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p><a href="https://link.springer.com/article/10.1007/s40279-020-01331-7?fbclid=IwAR06PPIz8cf2xZExNvrnlueQp0-7SWQwT1x0bUdnZrgTOqcyiAdTrpufTjU">Clinical trials</a> have consistently shown all adults – even very frail people over the age of 75 – can make significant gains in muscle mass and strength by doing progressive resistance training at least twice a week. The improvements can be seen in as little as eight weeks. </p>
<p><a href="https://pubmed.ncbi.nlm.nih.gov/2342214/">One seminal study</a> included ten frail, institutionalised 86–96 year olds who did a high-intensity progressive resistance training program. </p>
<p>After just eight weeks, the average mid-thigh muscle area had increased by almost 10% (which is equivalent to the amount of muscle typically lost over a decade) and leg strength increased by about 180%. </p>
<p>In other words, these older people were almost three times stronger at the end of the short training program than before.</p>
<p>It really can be done. British-Swiss man <a href="https://www.youtube.com/watch?v=rGgoCm1hofM">Charles Eugster</a> (1919–2017), for example, took up progressive resistance training in his late 80s after noticing a decline in his muscle mass. He went on to become a <a href="https://www.bodybuilding.com/fun/lessons-from-a-95-year-old-bodybuilder.html">bodybuilder</a>, and in 2012 gave a TEDx <a href="https://www.youtube.com/watch?v=rGgoCm1hofM">talk</a> titled “Why bodybuilding at age 93 is a great idea”.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525755/original/file-20230511-23-xwcq71.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6689%2C4466&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/525755/original/file-20230511-23-xwcq71.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6689%2C4466&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525755/original/file-20230511-23-xwcq71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525755/original/file-20230511-23-xwcq71.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525755/original/file-20230511-23-xwcq71.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525755/original/file-20230511-23-xwcq71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525755/original/file-20230511-23-xwcq71.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525755/original/file-20230511-23-xwcq71.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Resistance training is the most effective way to build and strengthen muscle at all ages.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>What if my doctor has told me to lose weight?</h2>
<p>Many older adults have obesity, which increases the risk of cardiovascular disease and type 2 diabetes. </p>
<p>They’re often told to lose weight, but any dieting (or other strategy aimed at weight loss) also usually causes muscle loss.</p>
<p>Losing muscle mass in older age could increase the risk for many common chronic conditions. For example, muscle is crucial to keeping blood sugar levels under control, so excessive muscle loss could blunt the benefits of weight loss for people with type 2 diabetes.</p>
<p>If you’re losing weight, it’s important to try to minimise muscle mass loss at the same time. How? Progressive resistance training. </p>
<p>By combining progressive resistance training with weight loss, one study found the resulting muscle loss is <a href="https://pubmed.ncbi.nlm.nih.gov/29596307/">negligible</a>. (It’s also important that if you are dieting, you are still eating <a href="https://www.clinicalnutritionjournal.com/article/S0261-5614(14)00111-3/fulltext">enough protein</a>, so your body has the ingredients it needs to build new muscle).</p>
<p>Exercise training during weight loss can also prevent <a href="https://www.sciencedirect.com/science/article/pii/S2095254621000491">bone loss</a>, which reduces fracture risk in older people.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/520175/original/file-20230411-26-v63lvh.jpg?ixlib=rb-1.1.0&rect=0%2C19%2C4368%2C2877&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/520175/original/file-20230411-26-v63lvh.jpg?ixlib=rb-1.1.0&rect=0%2C19%2C4368%2C2877&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/520175/original/file-20230411-26-v63lvh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/520175/original/file-20230411-26-v63lvh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/520175/original/file-20230411-26-v63lvh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/520175/original/file-20230411-26-v63lvh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/520175/original/file-20230411-26-v63lvh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/520175/original/file-20230411-26-v63lvh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An accredited exercise professional can help design a program that suits you.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Aim for at least twice a week – more if you can</h2>
<p>Whether or not you’re trying to lose weight, and regardless of whether you think you have sarcopenia, all older adults can benefit from strengthening their muscles.</p>
<p>Even if getting to a gym or clinic is hard, there are plenty of resistance exercises you can do at home or outdoors that will help build strength.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/525783/original/file-20230512-35478-3o1th8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/525783/original/file-20230512-35478-3o1th8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/525783/original/file-20230512-35478-3o1th8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525783/original/file-20230512-35478-3o1th8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525783/original/file-20230512-35478-3o1th8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525783/original/file-20230512-35478-3o1th8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525783/original/file-20230512-35478-3o1th8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525783/original/file-20230512-35478-3o1th8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">All older adults can benefit from strengthening their muscles.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Talk to a health professional before starting a moderate to high intensity progressive resistance training program. An accredited exercise professional can help design a program that suits you.</p>
<p>Generally, we should aim to do progressive resistance training at least <a href="https://link.springer.com/article/10.1007/s12603-021-1665-8">twice a week</a>.</p>
<p>Try to target 8–10 muscle groups, and start out at about 30–40% of your maximum effort before progressing over time to 70–80% of your maximum. </p>
<p>As the name suggests, it is key to progressively increase the effort or challenge of your program so you can feel the improvements and achieve your goals. </p>
<p>It’s never too late to start training for your fight against sarcopenia and loss of independence in older age. The health benefits will be worth it. As Socrates <a href="https://www.sacred-texts.com/cla/plato/theaetet.htm">said</a> in the 4th Century BC:</p>
<blockquote>
<p>is not the bodily habit spoiled by rest and idleness, but preserved for a long time by motion and exercise?</p>
</blockquote>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/use-it-or-rapidly-lose-it-how-to-keep-up-strength-training-in-lockdown-165810">Use it or rapidly lose it: how to keep up strength training in lockdown</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/203562/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Scott has been a consultant for Pfizer Consumer Healthcare and Abbott Nutrition. He has received competitive research funding from the National Health and Medical Research Council (NHMRC), Medical Research Future Fund (MRFF) and Amgen Australia. He is a Council member of the Australian and New Zealand Society for Sarcopenia and Frailty Research (ANZSSFR), and Chair of the ANZSSFR Sarcopenia Diagnosis and Management Taskforce.</span></em></p><p class="fine-print"><em><span>Robin Daly has received funding from the National Health and Medical Research Council (NHMRC), Medical Research Future Fund (MRFF), Eggs Australia, Meat and Livestock Australia, the Peanut Institute, Fonterra Co-operative Group Ltd as part of a Primary Growth Partnership grant via the Ministry of Primary Industries in New Zealand and Amgen Australia. He has previously received speaker honoraria from Abbott Nutrition, Fresenius Kabi, Nutricia Australia and Amgen. He is a member of the medical and scientific advisory committee of Healthy Bones Australia and a council member of the International Federation for Musculoskeletal Research Societies (IFMRS).
</span></em></p>It’s never too late to start.David Scott, Associate Professor (Research) and NHMRC Emerging Leadership Fellow, Deakin UniversityRobin M. Daly, Professor of Exercise and Ageing, Institute for Physical Activity and Nutrition, Deakin University, Deakin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2001672023-05-09T04:34:19Z2023-05-09T04:34:19ZWhy exercising your ‘good arm’ can also help the one in a sling<figure><img src="https://images.theconversation.com/files/522913/original/file-20230426-105-itdelq.jpg?ixlib=rb-1.1.0&rect=45%2C5%2C3788%2C2149&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/male-arm-sling-suffering-pain-shoulder-1461799133">Shutterstock</a></span></figcaption></figure><p>Injured limbs need rest. They are often kept in a sling or cast to immobilise them as a way to promote healing. But that can mean smaller and weaker muscles several weeks later. It takes a long time to rehabilitate these muscles and muscle strength and function <a href="https://link.springer.com/article/10.2165/00007256-199010010-00005">may not be fully restored</a> for some people.</p>
<p>Experts are learning more and more about the “<a href="https://theconversation.com/broke-your-arm-exercise-the-other-one-to-strengthen-it-103241">cross-education effect</a>” where training one side of the body results in an increased strength of the opposite side of the body. Our recent <a href="https://pubmed.ncbi.nlm.nih.gov/36849120/">study</a> shows it can also stop muscle wasting in the “unused” arm. </p>
<p>So, how can we harness that effect?</p>
<h2>How it works</h2>
<p>First <a href="https://vlp-new.ur.de/records/lit23174/files/lit23174_merged.pdf">discovered</a> 100 years ago, the mechanisms underpinning the cross-education effect have not been fully clarified yet. But it is <a href="https://pubmed.ncbi.nlm.nih.gov/29995227/">likely associated</a> with neural adaptations in the motor cortex of the brain that controls movement in the body. </p>
<p>Researchers have <a href="https://www.tandfonline.com/doi/epdf/10.1080/10833196.2018.1499272?needAccess=true&role=button">reviewed</a> almost 100 studies and showed the average cross-body transfer ratio between the strength gain in the trained muscle to non-trained muscle ranged from 48% to 77%. So, if your trained arm strength increased by 20% after training the same muscle of your non-trained arm strength might increase by 10% even though you did nothing with that arm.</p>
<p>Such changes <a href="https://pubmed.ncbi.nlm.nih.gov/29995227/">could be due</a> to increased cortical excitability (the brain activity to control movement), reduced cortical inhibition (the signal to stop movements), reduced inter-hemispheric inhibition (the signals that direct movement instructions to one side of the body but not the other), changes in voluntary activation or new brain regions getting switched on. </p>
<p>It appears the type of muscle contraction in the training affects the extent of the cross-education effect. </p>
<p>There are three types of muscle contractions: </p>
<ul>
<li>isometric (static) where the force produced by a muscle is equal to the load to the muscle, such as holding a dumbbell </li>
<li>concentric (shortening) in which force is greater than load, such as lifting a dumbbell</li>
<li>eccentric (lengthening) in which force is less than load, such as lowering a dumbbell. </li>
</ul>
<p>Muscles can produce greater force during eccentric than isometric or concentric contractions. And less fatigue is induced during eccentric than other contractions. <a href="https://www.betterhealth.vic.gov.au/health/healthyliving/resistance-training-health-benefits">Resistance exercises</a> – when muscles work against a weight or force – increase muscular strength and endurance using these types of muscle contractions.</p>
<p>Several <a href="https://pubmed.ncbi.nlm.nih.gov/26037804/">studies</a> report exercise consisting of <a href="https://pubmed.ncbi.nlm.nih.gov/26037804/">eccentric-only muscle contractions</a> (say, lowering a dumbbell but not lifting it) produces <a href="https://pubmed.ncbi.nlm.nih.gov/31524834/">greater cross-education effect</a> than exercise consisting of concentric-only (lifting only) or concentric-eccentric contractions (lifting and lowering). </p>
<p>One <a href="https://pubmed.ncbi.nlm.nih.gov/26037804/">study</a> showed eccentric exercise training affected brain-spine responses and stopping (inhibition) signals of the untrained limb to a greater extent than concentric training.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/522915/original/file-20230426-152-m0lbdx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="woman in gym setting holding dumbbell in one hand" src="https://images.theconversation.com/files/522915/original/file-20230426-152-m0lbdx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/522915/original/file-20230426-152-m0lbdx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522915/original/file-20230426-152-m0lbdx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522915/original/file-20230426-152-m0lbdx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522915/original/file-20230426-152-m0lbdx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522915/original/file-20230426-152-m0lbdx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522915/original/file-20230426-152-m0lbdx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Lowering a dumbbell is an example of an eccentric exercise.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fat-woman-holding-dumbbell-excessive-belly-1774886543">Shutterstock</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-foam-rolling-effective-for-muscle-pain-and-flexibility-the-science-isnt-so-sure-170878">Is foam rolling effective for muscle pain and flexibility? The science isn't so sure</a>
</strong>
</em>
</p>
<hr>
<h2>What we studied</h2>
<p>In 2021, we <a href="https://bmcsportsscimedrehabil.biomedcentral.com/articles/10.1186/s13102-021-00298-w">compared</a> eccentric and concentric resistance exercise training for cross-education effect in which 18 young people (aged 20–23) performed progressive elbow flexor resistance training with one arm twice a week for five weeks using a dumbbell.</p>
<p>Both eccentric (lengthening) and concentric (shortening) training groups increased muscle strength similarly after the training (by 23 to 26%) for the trained arm. But the non-trained arm showed greater strength increase after eccentric (23%) than concentric training (12%). The cross-body transfer ratio (the correspondence between the strength gain in both sides) was much greater (91%) for eccentric training when participants lowered a dumbbell only compared to concentric training (49%) when they lifted it.</p>
<p>This tallies with our previous <a href="https://pubmed.ncbi.nlm.nih.gov/31524834/">study</a> that showed greater strength gains and cross-education effect from eccentric training.</p>
<p>Published in February, our most recent study involved 12 young men and <a href="https://journals.lww.com/acsm-msse/Abstract/9900/Effects_of_Unilateral_Eccentric_versus_Concentric.216.aspx">showed</a> how training one arm can prevent weakening of the other. No training saw muscle strength and size of the inactive arm reduced by up to 17%. Concentric training reduced the loss to to 4%. But eccentric training increased the immobilised arm strength by 4% and completely abolished atrophy (muscle wasting). </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/four-reasons-swimming-should-be-your-next-workout-197249">Four reasons swimming should be your next workout</a>
</strong>
</em>
</p>
<hr>
<h2>What to ask your physio</h2>
<p>These findings support the recommendation of resistance training using eccentric or lengthening movements of the non-immobilised limb to prevent muscle strength loss and atrophy in real injuries such as ligament sprains and tears or bone fractures and after surgery.</p>
<p>This type of training has not been used extensively in rehabilitation so far. Further investigation into the mechanisms at play is needed but our findings could inform changes to how rehabilitation is implemented. </p>
<p>If you’re injured and or have had surgery and have an arm or leg immobilised, it’s worth discussing with your doctor, surgeon or physio whether exercising the corresponding limb on your good side – especially with lengthening movements against resistance or with a weight – could be worth trying. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/hot-pack-or-cold-pack-which-one-to-reach-for-when-youre-injured-or-in-pain-161086">Hot pack or cold pack: which one to reach for when you're injured or in pain</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/200167/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ken Nosaka 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>Working one arm or leg could help strengthen the corresponding injured or immobilised limb and also stop it wasting away from lack of use.Ken Nosaka, Professor of Exercise and Sports Science, Edith Cowan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1756102022-01-27T19:01:09Z2022-01-27T19:01:09ZGut microbes help hibernating ground squirrels emerge strong and healthy in spring<figure><img src="https://images.theconversation.com/files/442826/original/file-20220126-27-13smcdk.jpg?ixlib=rb-1.1.0&rect=63%2C369%2C3142%2C1959&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">When not hibernating, ground squirrels need to feast to store energy.</span> <span class="attribution"><a class="source" href="https://doi.org/10.1126/science.abh2950">Robert Streiffer</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Ground squirrels spend the end of summer gorging on food, preparing for hibernation. They need to store a lot of energy as fat, which becomes their primary fuel source underground in their hibernation burrows all winter long.</p>
<p>While hibernating, ground squirrels enter <a href="https://doi.org/10.1111/brv.12137">a state called torpor</a>. Their metabolism drops to as low as just 1% of summer levels and their body temperature can <a href="https://doi.org/10.1152/physrev.00008.2003">plummet to close to freezing</a>. Torpor greatly reduces how much energy the animal needs to stay alive until springtime.</p>
<p>That long fast comes with a downside: no new input of protein, which is crucial to maintain the body’s tissues and organs. This is a particular problem for muscles. In people, long periods of inactivity, like prolonged bed rest, <a href="https://doi.org/10.1186/s13728-015-0036-7">lead to muscle wasting</a>. But muscle wasting is minimal in hibernating animals. Despite as much as six to nine months of inactivity and no protein intake, they preserve muscle mass and performance remarkably well – a very handy adaptation that helps ensure a successful breeding season come spring.</p>
<p>How do hibernators pull this off? It’s been <a href="https://doi.org/10.1086/650471">a real head-scratcher</a> <a href="https://doi.org/10.1152/ajpregu.1991.261.5.R1214">for hibernation biologists for decades</a>. <a href="https://scholar.google.com/citations?user=TUVZbtcAAAAJ&hl=en&oi=ao">Our research</a> <a href="https://scholar.google.com/citations?user=zuJyGe8AAAAJ&hl=en&oi=ao">team tackled</a> this question by investigating how hibernating animals might be getting a major assist <a href="https://doi.org/10.1126/science.abh2950">from the microbes that live in their guts</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="small mammal curled into a ball, nestled in wood chips" src="https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The 13-lined ground squirrel shows minimal signs of muscle wasting, even after hibernating for up to six months.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1126/science.abh2950">Robert Streiffer</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>A nitrogen-recycling system</h2>
<p>We knew from previous research that a hibernator’s <a href="https://doi.org/10.1016/j.cbpa.2020.110875">gastrointestinal system undergoes dramatic changes</a> in its structure and function from summer feeding to winter fasting. And it’s not only the animals who are fasting all winter long – their gut microbes are, too. Along with our microbiology collaborators, we figured out that <a href="https://doi.org/10.1146/annurev-nutr-071816-064740">winter fasting changes the gut microbiome</a> quite a bit.</p>
<p>And then we wondered … could gut microbes play a functional role in the process of hibernation itself? Could certain bacteria help keep muscle and other tissues working when the mostly immobile animals aren’t eating?</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="brown cow munching grass" src="https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=671&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=671&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=671&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=843&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=843&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=843&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Microbes in their guts help ruminants, including cows, hold on to the nitrogen they need to build proteins.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/brown-cow-royalty-free-image/1219160750">Lemanieh/ iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Biologists had previously identified a clever trick in ruminant animals, such as cattle, that helps them survive times when protein intake in the diet is low or protein needs are especially high, such as during pregnancy. A process <a href="https://doi.org/10.1079/NRR200498">called urea nitrogen salvage</a> allows the animal to recoup nitrogen – a critical ingredient for building protein – that would otherwise be excreted in urine as the waste product urea. Instead, the urea’s nitrogen is retained in the body and used to make amino acids, the building blocks of proteins.</p>
<p>This salvage operation depends on the chemical breakdown of urea molecules to release their nitrogen. But here’s the kicker: Chemical breakdown of urea requires urease, an enzyme that animals do not produce. So how does a cow, for instance, get that nitrogen out of urea?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="ball and stick model of a chemical structure" src="https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A model of the urea molecule, with two nitrogen atoms (in blue) along with a carbon (gray), an oxygen (red) and four hydrogen (white) atoms.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/urea-molecule-royalty-free-illustration/147217473">LAGUNA DESIGN/Science Photo Library via Getty Images</a></span>
</figcaption>
</figure>
<p>It turns out certain microbes that are normal residents of animals’ guts can do just that. They make the urease enzyme and use it to chemically split urea molecules, freeing up the nitrogen, which becomes part of ammonia molecules. Microbes then absorb ammonia and use it to make new protein for themselves.</p>
<p>Peculiarities of the ruminant digestive system allow those animals to benefit greatly from this process. But for other animals – like hibernators and us – it was less clear whether and how the urea nitrogen could make its way into the animals’ bodies to support protein synthesis.</p>
<p>This was our challenge as scientists: Could we demonstrate urea nitrogen recycling in hibernators and show that it is particularly helpful to them the longer they fast?</p>
<h2>Our experimental game plan</h2>
<p>Using the 13-lined ground squirrel, <a href="https://doi.org/10.1126/science.abh2950">we designed experiments to investigate</a> key steps in urea nitrogen salvage.</p>
<p>First, we injected into the squirrel’s bloodstream urea molecules in which the two nitrogen atoms were replaced by a heavier form of nitrogen that naturally occurs only in tiny amounts in the body.</p>
<p>We were able to follow these heavier nitrogen atoms as the injected urea moved from the blood into the gut, then as microbial urease broke down the urea into its component parts, and finally into the squirrels’ tissue metabolites and proteins. Wherever we saw higher levels of the heavier form of nitrogen, we knew that urea was the source of the nitrogen, and therefore gut microbes had to be responsible for getting the urea nitrogen back into the animals’ bodies.</p>
<p>To confirm that the microbes were doing the nitrogen recycling, we compared squirrels that had normal gut microbiomes to squirrels that didn’t. We treated some animals with antibiotics to reduce gut microbes at three times of the year: summer; early winter, when they were one month into fasting and hibernation; and late winter, whwithen they were four months into fasting and hibernation.</p>
<p>In squirrels with normal microbiomes, we saw evidence of urea nitrogen salvage at each step of the process that we tested. But squirrels with depleted microbiomes displayed minimal urea nitrogen salvage. Our observations confirmed that this process was indeed dependent on the gut microbes’ ability to break down urea and liberate its nitrogen in the hibernators’ guts. Hibernators’ liver and muscle tissue incorporated the most urea nitrogen during late winter – that is, the longer they’d been hibernating and without food.</p>
<p>We also found that the ground squirrels contribute to this remarkable symbiosis. During hibernation, their gut cells increase production of proteins called urea transporters. These molecules are lodged in intestinal cell membranes and shepherd urea from the blood into the gut where the microbes that contain urease are found. This assist means that what little urea the animal makes during hibernation has an easier route to the gut.</p>
<p>Finally, we found that it wasn’t just squirrels who benefited from this process. The microbes too were using the urea nitrogen to build their own proteins, showing that urea nitrogen salvage provides both parties with this important molecular building block during the long winter fast.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Fal-vhNgxvs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Every few weeks, hibernating squirrels arouse temporarily, as seen in this time-lapse video. They don’t eat or drink or leave the burrow, but the short increase in body temperature lets enzymes like urease do their jobs.</span></figcaption>
</figure>
<h2>Could this kind of symbiosis help humans?</h2>
<p>This example of hibernator-microbe symbiosis has potential clinical applications. For example, undernourishment, which affects millions of people globally, leads to a progressive decline in muscle mass and compromises health. Sarcopenia, which is muscle wasting that is a natural part of aging, impairs mobility and makes people more susceptible to injury. A detailed understanding of how the hibernator nitrogen salvage system is most effective when the risk of tissue loss and muscle wasting is greatest could lead to new therapeutics to help people in similar situations.</p>
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<p>Another potential application is in human spaceflight, during which crew members experience <a href="https://doi.org/10.33549/physiolres.934550">high rates of muscle atrophy</a> because of a microgravity-induced suppression of muscle protein synthesis. Even the extensive exercise regime that astronauts undertake to offset this is insufficient. A microbiome-based countermeasure that facilitates muscle protein synthesis similar to the process we have observed in hibernators may be worth investigating.</p>
<p>These applications, though theoretically possible, are a long way from delivery. But studies in the 1990s demonstrated that humans are capable of <a href="https://doi.org/10.1097/01.mco.0000196142.72985.d3">recycling small amounts of urea nitrogen with the help of their gut microbes</a>. So the necessary machinery is in place – it just needs to be optimized.</p><img src="https://counter.theconversation.com/content/175610/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hannah V. Carey received funding from the U.S. National Science Foundation for this work.</span></em></p><p class="fine-print"><em><span>Matthew Regan receives funding from the Natural Sciences and Engineering Research Council of Canada and the Canadian Space Agency.</span></em></p>Months not eating or moving don’t result in muscle wasting and loss of function for animals that hibernate. New research found gut microbes help their hosts hold onto and use nitrogen to build proteins.Hannah V. Carey, Professor Emeritus of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-MadisonMatthew Regan, Assistant Professor of Biological Sciences, Université de MontréalLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/394412015-03-28T11:07:35Z2015-03-28T11:07:35Z#YearInSpace mission could do wonders for your grandad – here’s how<figure><img src="https://images.theconversation.com/files/76281/original/image-20150327-16135-8phxzp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Space suits you.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&search_tracking_id=LSE79681DYzqGQVP19aYzQ&searchterm=old%20man%20outer%20space&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=127510175">Kostolom3000</a></span></figcaption></figure><p>NASA has <a href="http://www.ibtimes.com/pulse/one-year-crew-ready-launch-international-space-station-twins-science-deep-space-1859414">sent</a> an astronaut to the International Space Station to stay there for a year. Though Russian cosmonauts have achieved this feat before, the mission aims to help us to better understand how humans adapt to the spaceflight environment and the effects of countermeasures such as drugs and exercise that help them cope. </p>
<p>Exposure to the low gravity associated with spaceflight is well established to cause deterioration of various bodily systems. Symptoms that astronauts consistently report when they return to Earth include loss of bone mass, fluid shifts towards the head, under-par heart performance and immune system dysfunction. </p>
<p>But one of the most significant changes that we see in astronauts and indeed all species that we have examined in space is loss of muscle size and function. This is comparable to the reduced exercise capacity and increased frailty that you might expect from someone who has been severely restricted for a long period of time. </p>
<p>As the world’s space agencies plan <a href="http://www.nasa.gov/press/2015/march/nasa-announces-next-steps-on-journey-to-mars-progress-on-asteroid-initiative/">longer, more ambitious missions</a>, this poses a major challenge. Astronauts lose <a href="https://www.nasa.gov/mission_pages/station/research/experiments/245.html">as much as 40%</a> of muscle mass after 180 days onboard the International Space Station. This would be enough to seriously impair their ability to carry out mission activities during an 18-month trip to Mars, for example. </p>
<p>Perhaps more worryingly, because muscle carries out several metabolic processes such as burning fat, this level of muscle wasting could help lead to metabolic ailments such as type 2 diabetes, cardiovascular disease and obesity. It is this significant threat to astronaut health and physical performance that NASA is seeking to prevent as part of the upcoming one-year expedition.</p>
<h2>What causes loss of muscle?</h2>
<p>Despite decades of manned spaceflight and research, the causes of muscle wasting remain unclear at the molecular level. This is due in no small part to the large technical and monetary constraints associated with conducting scientific experiments in space. Nevertheless, studies that have looked at living things from tiny worms all the way to humans <a href="http://www.ncbi.nlm.nih.gov/pubmed/24217152">have provided</a> two likely candidates. </p>
<p>The first is the fact that in spaceflight, the force of gravity upon our bodies is greatly reduced. Our muscles possess molecular sensors that in Earth conditions convert the mechanical strain produced when we exert ourselves into signals that make muscle grow. </p>
<p>During spaceflight, however, the amount and effectiveness of these sensors are lowered by the much weaker gravity. This in turn reduces the molecular signals that maintain healthy muscle. This poses the question of whether appropriate exercise regimens employed by astronauts might rejuvenate these sensors to offset muscle loss during spaceflight.</p>
<p>The second likely factor is that astronauts frequently fail to eat sufficient amounts of food to meet their daily energy requirements. Restricting calorie intake might impair the ability of muscle cells to use and respond to insulin and ultimately lead to type-2 diabetes. </p>
<p>This deficiency would reduce muscle growth or increase wasting signals, causing the size and quality of muscles to decline and increasing the risks of <a href="http://www.webmd.com/heart-disease/vascular-disease">vascular disease</a>. Because this insulin problem is responsive to both nutrition and exercise, it once again points to the importance of looking at the best ways of using them to offset it. </p>
<h2>What the mission aims to achieve</h2>
<p>NASA will address two key questions in relation to muscle health during the one-year mission. The first is whether the known muscle loss over six months onboard the space station continues to deteriorate with longer stays in space: there is still no evidence that astronaut muscle decline ever plateaus. </p>
<p>The second is whether new exercise programmes are capable of preventing muscle decline in flight. This is of particular importance since to date, all tested methods including treadmill running, rowing, cycling and simple resistance exercises have proven ineffective at preventing the problem.</p>
<p>The mission will assess the effectiveness of two different kinds of exercise: high-intensity sprint cycle training and the newly developed advanced resistance exercise device – dubbed the astronauts’ weight-lifting machine. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/7oBvNxbTF28?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>There is good reason to anticipate a better muscle response to these. The advanced resistance exercise device is designed to provide the additional load to specific muscle groups that is perhaps needed to “re-activate” the muscles’ mechanical sensors in the absence of Earth’s gravitational pull. </p>
<p>High-intensity sprint cycle training has been shown on Earth to be even more effective than traditional endurance exercise for improving muscles’ ability to respond to insulin. So this could potentially provide the intensity of stimulus required to counteract spaceflight-induced insulin resistance. </p>
<h2>What this means for life on Earth</h2>
<p>Besides Mars mission enthusiasts, many may be wondering why they should care about any of this. Several strong and valid arguments have been put forward to justify the significant public expenditure that this research involves. </p>
<p>These include the notion that the survival of humankind ultimately centres on our ability to inhabit other planetary bodies. That potential “return on investment” is an order of magnitude greater than the value of any exploratory venture yet embarked upon by our species, goes the argument. </p>
<p>More immediate benefits may present themselves, though. The muscle problems from spaceflight closely resemble those caused by numerous conditions on Earth, including long periods of bed rest, muscular dystrophies, cardiovascular diseases and type-2 diabetes. </p>
<p>In particular, the ageing process also displays a striking similarity with the changes that occur in space, albeit over a more prolonged timeframe. Many <a href="http://www.ncbi.nlm.nih.gov/pubmed/19851058">have proposed</a> that spaceflight is like an accelerated version of ageing. </p>
<p>In short, the unique stresses imposed by living in space provide an opportunity to study, understand and develop countermeasures to some of the most prominent health challenges faced by the human race. The question should therefore not be “why should we continue exploring space”, but rather “why wouldn’t we?”</p><img src="https://counter.theconversation.com/content/39441/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nate receives funding from BBSRC, MRC, ARUK, ESA and NASA. In the past he has also received funding from US NIH and the UK Space Agency
</span></em></p><p class="fine-print"><em><span>Tim Etheridge receives funding from The Japan Society for the Promotion of Science.</span></em></p>NASA’s latest mission to the International Space Station is going to study muscle wasting, among other things. Here’s what they hope to find out.Nate Szewczyk, Associate Professor, Faculty of Medicine and Health Sciences, University of NottinghamTim Etheridge, Lecturer, University of ExeterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/351132014-12-08T05:59:21Z2014-12-08T05:59:21ZGrannies get physical: how bodybuilding may hold the key to a major ageing problem<figure><img src="https://images.theconversation.com/files/66405/original/image-20141205-8636-1o6ueej.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Take the strain.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/zanthia/12559719874/in/photolist-dYDztz-mb5m5q-jY5ysa-77XGzc-4Jw5o6-g8qAXS-e4raaW-fH6Ph-HZE2q-49qQ6-5NJx7r-7i1ev7-3yjeZZ-4Th99-6MUCzs-oykbfG-cWzreC-k8RR9o-jdzB6-aBzRb3-2ucE28-dJfAWQ-ack1Um-3Nh2iX-6zZbT8-85vyQU-41Xxu6-7MPe4X-7dNx9J-7MTatq-6c6j58-GegbS-pXuzyn-aqYwvB-4fdWhG-5ms878-7fpw6k-ht5VXC-pkgLv8-ijvuXU-Q6gpV-9c3Nfe-jsAb5-abej5Y-4191na-mtYRPv-88gJ3-ATDA-4zDCFX-9qNDQC">Chris Zielecki</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>People have used bodybuilding to improve their physical performance for at least 1,500 years. The first recorded example was the sixth-century wrestler, <a href="http://www.britannica.com/EBchecked/topic/383062/Milo-of-Croton">Milo of Croton</a>, in southern Italy. Milo reportedly carried out his daily exercises with a calf on his back. As the calf grew into a full sized ox, so too did Milo’s legendary strength. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/66407/original/image-20141205-8658-15e3wjo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66407/original/image-20141205-8658-15e3wjo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/66407/original/image-20141205-8658-15e3wjo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=839&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66407/original/image-20141205-8658-15e3wjo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=839&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66407/original/image-20141205-8658-15e3wjo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=839&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66407/original/image-20141205-8658-15e3wjo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1055&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66407/original/image-20141205-8658-15e3wjo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1055&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66407/original/image-20141205-8658-15e3wjo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1055&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Milo, original muscle man.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/zanthia/12559719874/in/photolist-dYDztz-mb5m5q-jY5ysa-77XGzc-4Jw5o6-g8qAXS-e4raaW-fH6Ph-HZE2q-49qQ6-5NJx7r-7i1ev7-3yjeZZ-4Th99-6MUCzs-oykbfG-cWzreC-k8RR9o-jdzB6-aBzRb3-2ucE28-dJfAWQ-ack1Um-3Nh2iX-6zZbT8-85vyQU-41Xxu6-7MPe4X-7dNx9J-7MTatq-6c6j58-GegbS-pXuzyn-aqYwvB-4fdWhG-5ms878-7fpw6k-ht5VXC-pkgLv8-ijvuXU-Q6gpV-9c3Nfe-jsAb5-abej5Y-4191na-mtYRPv-88gJ3-ATDA-4zDCFX-9qNDQC">Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>In the 1940s this concept of what has come to be known as progressive resistance exercise was developed more scientifically by US Army physician <a href="http://www.ncbi.nlm.nih.gov/pubmed/22592167">Thomas DeLorme</a> to assist the recovery of injured service men and polio sufferers. It is a simple idea: lift a weight you can manage for a set routine and when after numerous training sessions it becomes too light, increase the weight. You repeat the process over and over and it leads to substantially improved strength. This is because the muscle adapts by growing to deal with heavier loads. DeLorme applied these principles to his own physical training and is said to have been formidably strong. </p>
<h2>Our little protein factories</h2>
<p>Thanks to these insights, in modern-day bodybuilding we now have a very good idea of how to improve muscle mass and strength. Muscle growth with progressive resistance exercise is a good example of how adaptable our skeletal muscle is. Part of the mechanism by which muscle grows is through a process called protein synthesis. Muscle grows by increasing the rate at which proteins are made, since muscle is made from protein. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66408/original/image-20141205-8655-bv16rr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66408/original/image-20141205-8655-bv16rr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66408/original/image-20141205-8655-bv16rr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66408/original/image-20141205-8655-bv16rr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66408/original/image-20141205-8655-bv16rr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66408/original/image-20141205-8655-bv16rr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66408/original/image-20141205-8655-bv16rr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66408/original/image-20141205-8655-bv16rr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">So macho!</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&searchterm=bodybuilder&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=234981475">Kiselev Andrey Valerevich</a></span>
</figcaption>
</figure>
<p>Protein synthesis also responds to eating dietary protein. And when protein is consumed following resistance exercise, muscle production is enhanced even further. <a href="http://jap.physiology.org/content/106/5/1692">What’s more</a>, muscles that have been subjected to resistance exercises increase their protein synthesis rates more than non-exercised muscles after each meal for at least the next 48 hours. </p>
<p>Not only is this insight useful for bodybuilders, it also tells us something useful about muscle wasting. We know that slow wasting conditions such as <a href="http://www.webmd.com/healthy-aging/sarcopenia-with-aging">sarcopenia</a>, where muscle mass progressively diminishes with age, are <a href="http://journals.lww.com/co-clinicalnutrition/pages/articleviewer.aspx?year=2012&issue=01000&article=00010&type=abstract">due to</a> the impaired ability of muscle to increase protein production in response to feeding or loading. In effect, the muscle’s protein-building machinery becomes resistant to growth stimuli. This causes the protein, and hence the muscle, to be lost, which leads to reduced muscle function. </p>
<p>This is important because muscle loss with age is associated with impaired physical function and loss of independence. This is particularly true if it is combined with the muscle wasting that people experience if they are immobilised after injuries or surgery. <a href="http://www.ncbi.nlm.nih.gov/pubmed/9302893">For example</a>, around 50% of women over the age of 65 who break a hip never walk again. The cause? Loss of muscle mass associated with the injury and the ensuing bed rest. </p>
<p>Sarcopenia is also associated with an increased risk of falling. <a href="http://jech.bmj.com/content/57/9/740.long">A review</a> of the cost of treating fall-related injuries in 1999 showed that falls in the over-60s cost the UK government close to a £1bn a year (more than £1.5bn in today’s money). There is therefore a huge public interest in developing safe and effective strategies to prevent muscle wasting. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/66410/original/image-20141205-8667-34m0wu.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/66410/original/image-20141205-8667-34m0wu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/66410/original/image-20141205-8667-34m0wu.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=355&fit=crop&dpr=1 600w, https://images.theconversation.com/files/66410/original/image-20141205-8667-34m0wu.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=355&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/66410/original/image-20141205-8667-34m0wu.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=355&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/66410/original/image-20141205-8667-34m0wu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=446&fit=crop&dpr=1 754w, https://images.theconversation.com/files/66410/original/image-20141205-8667-34m0wu.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=446&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/66410/original/image-20141205-8667-34m0wu.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=446&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Muscle wasting is worst when ageing and injury combine.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/mayoclinic/7351848916/in/photolist-ccE9xN-7jPtLB-7jPxRD-7jPx7M-7jPA7r-7jPzLM-7jPAbg-7jPuyX-7jPAgz-5Y2kh2-7jTnMs-7jTDi7-7jTqfC-7jTpPb-7jToX3-7jPwvz-7hNNTV-7jTu5G-5cEoHE-5TrHnZ-7jPBU6-7jTutG-7jPAs2-7jTFf3-7jPM3K-7jPB3x-7jPDmg-7jTFNd-7jPCnB-7jPCte-7jPJjR-7jTv2s-7jTxwf-5cA7ec-7jTygj-7jHgZs-7jHgkN-7jTDUh-7jPMbR-7jTyAq-7jTEbm-7jPL9F-7jPM6n-7jTF8J-7jTDqy-7jPK44-7jHxUo-7jHzPh-7jHseE-7jDFyc">Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>The research race</h2>
<p>We have been aware of this link between muscle wasting and protein synthesis impairment for a long time. You don’t see many old people in the gym lifting weights, but that is exactly what they should be doing to try and offset these effects. </p>
<p>For the vast majority of abstainers, researchers have been looking for potential drug treatments in this area for more than 30 years. And for about the last 15 they have been employing biochemistry techniques in human studies to try and understand the molecular signals that tell the muscle to grow. </p>
<p>These molecular signals act like the foreman on a building site. They read the conditions by sensing whether there is sufficient building materials and manpower to build and whether there has been a change in demand on the existing muscle. They then relay that information into an appropriate growth response to meet the demands placed on the system by initiating or stopping muscle protein synthesis. </p>
<p>The question is which molecules are doing this foreman’s job, which has proved far harder to ascertain than initially might have been hoped. The combined efforts of researchers these past few years have pointed to the likelihood that the culprit is a molecule called p70S6K1. Various teams are now looking at how it potentially leads to more muscle protein being produced, including my own. </p>
<p>One reason why it has taken a long time for anyone to fully explain what happens is because it is hard to measure how this molecule functions in human skeletal muscle. This makes it harder to determine its role in making muscles grow. We <a href="http://jap.physiology.org/content/110/2/561">have optomised</a> a simple, cost-effective and accurate technique to solve this measuring difficulty. We have already been putting it through human trials, and hope to have a definitive answer in the next five to ten years. </p>
<p>While others take different approaches, the race is on to determine whether p70S6K1 will be a good drug target to treat muscle wasting. After that, it might take another couple of decades to develop commercial drugs. Needless to say, solving the riddle of muscle wasting is not a quick process. But if science finally triumphs here, it will be a great example of how the answers to problems can come from the most unlikely of sources. For now though, the best advice is to take the lead from bodybuilding and undertake a programme of progressive resistance exercise while ensuring you consume adequate amounts of protein.</p><img src="https://counter.theconversation.com/content/35113/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lee holds funding from the Insulin-dependant Diabetes Trust, the Society for Endocrinology and the American College of Sports Medicine.</span></em></p>People have used bodybuilding to improve their physical performance for at least 1,500 years. The first recorded example was the sixth-century wrestler, Milo of Croton, in southern Italy. Milo reportedly…Lee Hamilton, Lecturer in Sport, Health and Exercise Science, University of StirlingLicensed as Creative Commons – attribution, no derivatives.