In a new study, researchers found decades-long endurance training alters the activity of genes in human skeletal muscle that are important for metabolic health.
Sex differences found in untrained people were also dramatically reduced with long-term training. The results may have implications for metabolic disease prevention.
The research was conducted by a team at Karolinska Institutet in Sweden and the University of San Diego in the U.S.
Exercise training performed over a lifetime is known to result in numerous health benefits and can prevent diseases such as type 2 diabetes, heart disease, and cancer but the mechanisms behind these effects are not completely understood.
The current study included people who had performed intensive exercise training for at least the past 15 years, either long-term endurance training (9 men/9 women) or strength-training (7 men), as well as age-matched untrained healthy controls (7 men/8 women).
Skeletal muscle biopsies were collected from all 40 volunteers, and RNA sequencing was performed to measure the activity of over 20,000 genes.
The team found long-term endurance training (running or cycling) significantly changed the activity of more than 1,000 genes in both women and men compared with controls.
Many of the altered genes were related to increased activity in numerous metabolic pathways related to the prevention of metabolic diseases, such as type 2 diabetes.
Surprisingly, only 26 genes were found to be changed with long-term weightlifting, suggesting that strength training does not result in accumulated changes in gene activity.
However, the researchers note that this does not mean gene activity is unaffected with weightlifting, it could be that changes in muscle gene activity with weightlifting are related to proteins instead of RNA.
More than 450 genes were found to be expressed differently in the muscles of the untrained male volunteers versus their female counterparts.
Such sex differences are known to exist, but the new study demonstrates that sex differences decreased by about 70% with long-term endurance training.
The researchers also cross-referenced their data with studies examining muscle gene expression before and after a months-long training period in individuals with type 2 diabetes.
The results show that following short exercise programs, people with impaired metabolism shifted their gene activity to become more similar to the long-term endurance-trained groups compared with before they started training.
This suggests that even short training programs of 6–12 months are enough to positively influence the health of people suffering from metabolic disorders.
One author of the study is Mark Chapman, an assistant professor at the Department of Integrated Engineering, University of San Diego.
The study is published in Cell Reports.
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