Abstract
Exercise plays a crucial role in promoting overall health by activating molecular pathways that contribute to the prevention and management of chronic diseases, slowing epigenetic aging, improving body composition, and reducing the risk of obesity. In skeletal muscle, these benefits are largely mediated by exercise-induced transcriptional and epigenetic responses. Recent advances in epigenetics have intensified interest in understanding how physical activity influences long-term health and body composition at the molecular level. Epigenetic modifications, which regulate gene expression without altering the DNA sequence, are key mechanisms in this process. Emerging research has provided deeper insights into the processes such as DNA methylation, histone modification, and non-coding RNAs, and their connection to exercise. While numerous studies have demonstrated the influence of exercise on the epigenome, fewer have directly examined how these molecular changes relate to alterations in fat mass, lean body mass, and other components of body composition. This comprehensive review synthesizes the current evidence on the interplay between exercise, epigenetic regulation, and body composition, with a focus on adolescents and adults. We highlight key genes involved in metabolism, fat storage, muscle development, and epigenetic aging, and explore how their regulation may contribute to individual variability in exercise response. Understanding these molecular pathways may provide valuable insights for optimizing exercise interventions aimed at improving health outcomes across the lifespan.