Researchers find long-term endurance may change musculoskeletal tissue

December 22, 2014

Topic: orthopaedic injury

Researchers from the Karolinska University in Sweden discovered that people who undergo long-term endurance training may be changing their human skeletal muscle.

Researchers from the Karolinska University in Sweden discovered that people who undergo long-term endurance training may be changing their human skeletal muscle. For years, research has proven that physical activity is one of the keys to good health. The U.S. Centers for Disease Control and Prevention noted that research has proven several positive effects of physical activity, including strengthening of the bones and muscles,  a reduced risk of orthopaedic injuries such as a hip fracture, and alleviated pain from arthritis. Regular physical activity has also been correlated with lowering the chances of cardiovascular disease and reducing the risk for cancer and diabetes. It even may be tied to improved mental health and a lower risk of depression.

Yet very few studies have investigated exactly why physical activity makes the body so much healthier. Now, researchers found that it may have to do with a little something called epigenetics. 

Subtle differences
Epigenetics is when various environmental factors affect the genome, temporarily changing it biochemically. Several different types of epigenetic changes can occur. One particular change is known as methylation, when a methyl group is added or changed from a base in a DNA molecule without affecting the DNA sequence studied. Genes are only active at certain times, so methylation uses cells to determine which genes to activate. 

The findings were published in the journal Epigenetics.

Noticing the changes
The study used 23 young, athletic men and women who were asked to perform one-legged cycling, with the untrained leg acting as the control. The participants cycled four times a week for 45 minutes at a time. They did this for three months. The researchers measured participants' legs before and after the training sessions. In the examinations, the scientists looked for the skeletal muscle metabolism, to examine what genes might be activated by cells. They studied over 20,000 genes.

"We found that endurance training in a coordinated fashion affects thousands of DNA methylation sites and genes associated to improvement in muscle function and health", lead researcher Carl Johan Sundberg said in a statement. "This could be of great importance for the understanding and treatment of many common diseases such as diabetes and cardiovascular disease, but also for how to maintain a good muscle function throughout life. Interestingly, we also saw that there were epigenetic differences between male and female skeletal muscle, which may be of importance to develop gender specific therapies in the future."

The findings revealed that the cells had made noticeable changes in 4,000 of all the measured genes. The study authors also found that these genes were involved in changes in the muscles as well as the breaking down of carbohydrates. If the region of muscle did not show any methylation process, then the scientists concluded that the muscle was inflamed. 

The study authors noticed that most of the changes happened in a region known as the enhancers, which regulate the genome. The enhancers normally are far away from where the actual genomes are situated, unlike promoters, which are much closer to the genes they control.

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