Epigenetic Skeletal Muscle Memory: The Impact of Physical Activity on Aging and Post-Injury Regeneration.

Skeletal muscle retains adaptive information from previous mechanical loading, enabling faster responses to subsequent training and regenerative challenges. This review synthesizes current evidence on the cellular and epigenetic mechanisms underlying skeletal muscle memory and examines how these mechanisms are modified by aging and post-injury regeneration. Muscle memory emerges from complementary structural and molecular components, including myonuclear retention, persistent DNA methylation changes, chromatin remodeling, transcriptional priming, non-coding RNA regulation, and mitochondrial epigenetic adaptations. These mechanisms interact with muscle satellite cells (MuSCs), fibro-adipogenic progenitors (FAPs), immune cells, and extracellular matrix remodeling to maintain regenerative competence. During aging, epigenetic drift, chronic low-grade inflammation, altered macrophage states, MuSC dysfunction, persistent FAP activity, fibrosis, mitochondrial impairment, and anabolic resistance progressively reduce this plasticity, thereby contributing to sarcopenia. Training-detraining-retraining studies indicate that parts of the exercise-induced epigenetic landscape remain detectable after training cessation and can be reactivated during renewed loading, although the persistence and functional importance of individual molecular signatures remain incompletely defined. Physical exercise remains the most established intervention for preserving muscle function and epigenetic responsiveness, whereas caloric restriction, modulation of nutrient-sensing pathways, senolytic strategies, and direct targeting of epigenetic regulators remain promising but translationally less mature approaches. Overall, the preservation of epigenetic plasticity may be a key determinant of healthy skeletal muscle aging and effective regeneration.