According to findings in a recent study published in the journal “eLife,” scientists have revealed that high-intensity interval training (HIIT) has significant effects on human skeletal muscle, increasing the total amount of protein needed for muscle contraction and energy metabolism. † These results may explain the beneficial effects of HIIT on metabolism and pave the way for additional studies examining how exercise affects these processes.
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“Exercise has many beneficial effects that can help prevent and treat metabolic diseases, and this is likely due to changes in skeletal muscle energy expenditure. We wanted to understand how exercise changes muscle protein content and how it affects the activity of these muscles. proteins through a chemical reaction called acetylation,” said lead and co-corresponding author Morten Hostrup, associate professor in the Department of Nutrition, Exercise and Sport at the University of Copenhagen, Denmark.
Acetylation occurs when a member of the small molecule group, acetyl, combines with other molecules and can affect the behavior of proteins. For their study, the team recruited eight healthy, untrained male volunteers to complete five weeks of intense cycling training. The men trained three times a week and finished four minutes of cycling at a target rate of more than 90% of their maximum heart rate, followed by two minutes of rest.
They repeated this pattern four to five times per workout. Using a technique called mass spectrometry, the team analyzed changes in the composition of 3,168 proteins in tissue samples collected from the participants’ thighs before the study and after they completed training. They also examined changes involving 1,263 lysine acetyl sites on 464 acetylated proteins.
Their analyzes showed an increase in the production of proteins used to build mitochondria, which produce energy in cells, and in proteins associated with muscle contractions. The team also identified increased acetylation of mitochondrial proteins and enzymes involved in cellular energy production. In addition, they observed changes in the number of proteins that reduce the calcium sensitivity of skeletal muscle, which is essential for muscle contractions.
The results confirm some known changes in skeletal muscle proteins that occur after exercise, and also identify new ones. For example, the decreased calcium sensitivity may explain why it may be more difficult for muscle contraction after an athlete has fatigued. The work also suggests that exercise-induced changes in protein regulation through acetylation may help boost metabolism.
“By using state-of-the-art proteomics technology, our study provides new information on how skeletal muscle adapts to exercise training, including the identification of novel exercise-regulated proteins and acetyl sites,” concludes co-corresponding author Atul Deshmukh, Associate Professor at the Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen. “We hope our work will stimulate further research into how exercise helps improve people’s metabolic health.”