New Insights Into the Mechanisms Underlying Muscle Adaptations From Endurance Training

A study conducted by researchers at the University of Basel has yielded new insights into the transformation of muscle structure induced by endurance training. The study, which used mice as subjects, found that endurance training leads to considerable changes in muscle composition, specifically in the manner in which genes are expressed depending on the training state of the muscles. These changes are principally governed by epigenetic factors that modify gene activation, thereby making trained muscles more adept at handling sustained periods of exercise.

The fitness of our muscles improves commensurately with increased endurance exercise. These muscles adapt to the exertion, leading to enhanced performance over extended periods. New understanding of these adaptive mechanisms has now been presented by scientists.

The merits of endurance training are numerous. Regular engagement in such exercises not only boosts overall health and fitness but also instigates significant structural modifications in muscles. These changes manifest in commonly observed training benefits, such as decreased muscle fatigue, increased energy production, and more efficient utilization of oxygen. A team of researchers from the University of Basel delved into the molecular intricacies of these muscle alterations, with their experiments on mice serving as the foundational data.

Professor Christoph Handschin, who has been conducting long-term research in muscle biology at the University of Basel’s Biozentrum, stated, “The phenomenon of muscle adaptation to physical activity is well-established. Our aim was to decipher the specific occurrences in the muscle during exercise training.” The team has subsequently published their novel findings in the journal Nature Metabolism.

Genetic Markers Indicative of Training State

In their recent work, Handschin’s team juxtaposed the muscles of trained mice with those of untrained ones to discern alterations in gene expression due to training. Lead author Regula Furrer noted, “Given that endurance training causes substantial muscle alterations, we hypothesized that these changes would manifest in gene expression.” Contrary to their initial expectations, the study found that in resting muscles, only about 250 genes displayed altered expression when comparing trained to untrained muscles. However, an acute exercise bout led to the regulation of 1,800 to 2,500 genes, the specific number and identity of which were largely determined by the training state of the muscle.

Differential Response to Exercise Stress in Muscles

Untrained muscles, when exposed to endurance training, exhibit activation of inflammatory genes due to minor injuries, commonly referred to as muscle soreness. In trained mice, however, the study observed activation of protective genes, resulting in muscles that were more resilient and efficient in dealing with physical stress.

Epigenetic Changes Underpin Muscle Adaptability

The investigators discovered that epigenetic changes were responsible for the disparate muscle responses to endurance exercise. These changes involve chemical modifications in the genome that turn genes on or off. Remarkably, the study found significant differences in epigenetic patterns between trained and untrained muscles. “Numerous key genes that control the expression of an array of other genes undergo these epigenetic modifications,” emphasized Furrer.

This epigenetic information is pivotal in shaping how muscles adapt to endurance training. “The long-term and short-term epigenetic changes that occur in muscles due to chronic endurance training prime them for extended workouts. These muscles become more efficient and respond more quickly,” summarized Handschin.

Future Directions

The current study has elucidated how muscles adapt to sustained endurance training in mice. The ensuing challenge is to determine whether these observations are applicable to humans. In the context of competitive sports, potential biomarkers of training progress could serve to enhance training efficiency. Moreover, understanding healthy muscle function is essential for developing treatments for age- or disease-related muscle degradation.

Reference: “Molecular control of endurance training adaptation in male mouse skeletal muscle” by Regula Furrer, Barbara Heim, Svenia Schmid, Sedat Dilbaz, Volkan Adak, Karl J. V. Nordström, Danilo Ritz, Stefan A. Steurer, Jörn Walter and Christoph Handschin, published on September 11, 2023, in Nature Metabolism. DOI: 10.1038/s42255-023-00891-y.

Frequently Asked Questions (FAQs) about Endurance Training and Muscle Adaptation

More about Endurance Training and Muscle Adaptation

• University of Basel’s Biozentrum Research
• Nature Metabolism Journal
• Overview of Epigenetic Changes
• Muscle Adaptation and Exercise
• Gene Expression in Endurance Training
• Muscle Soreness and Inflammatory Response
• Understanding Biomarkers in Sports Training
• Muscle Wasting Diseases and Treatments