It is recommended that adults perform at least 30 minutes of moderate-intensity aerobic exercise five days a week to reduce the risk of heart disease, stroke, obesity, and many other diseases. A new study has found that long-term endurance training actually changes the way genes are expressed in skeletal muscle, improving metabolism and controlling inflammation. This information could be used to prevent and treat diseases associated with a sedentary lifestyle. Carl Johan Sundberg of the Karolinska Institutet in Sweden was principal investigator of the project, and the paper was published in Epigenetics.

“It is well-established that being inactive is perilous, and that regular physical activity improves health, quality of life and life expectancy,” Sundberg said in a press release. “However, exactly how the positive effects of training are induced in the body has been unclear. This study indicates that epigenetics is an important part in skeletal muscle adaptation to endurance training.”

For the three-month-long study, 23 healthy young adults engaged in 45 minutes of endurance training four times a week. The participants cycled with one leg, using the leg not completing exercise as a control. Muscle biopsy samples were taken from each leg, both before and after the study. The researchers were looking for epigenetic changes, that is, temporary changes to genetic expression due to environmental factors. Activity levels of more than 20,000 genes were analyzed, and 480,000 loci were checked for methylation. Methylation of DNA impacts the level at which a gene is expressed.

Ultimately, Sundberg’s team found a relationship between change in methylation and activity of about 4,000 genes. Increased methylation was seen in regions of genes associated with metabolism and the ability for muscle to adapt. Areas with decreased methylation were tied to genes responsible for inflammation. The majority of these epigenetic changes weren’t located on the gene itself or even in the promotor region, which would have been expected. Instead, the methylation changes were seen in the enhancer regions which are located relatively far away from the gene in question.

“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,” added Sundberg. “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.”

In order to fully understand the therapeutic potential of endurance training to make these epigenetic changes, future studies may use a larger group of participants, utilize different exercises, investigate how long the changes last, and explore whether or not the effect is dose-dependent.