Effects of prolonged physical training on skeletal muscle mass accrual throughout the life span

Skeletal muscle mass (SMM) is a key determinant of physical performance, metabolic health, and functional capacity across the lifespan. This paper provides an evidence-based overview of the effects of exercise on SMM accrual across different age groups and associated practical applications for exercise training. Evidence suggests that hypertrophic responses may vary across the lifespan, with differences observed between children and youth, middle-aged, and older populations. In younger and middle-aged populations, the primary training objective should be directed toward increasing SMM, while in older individuals, resistance training is particularly relevant for mitigating age-related declines in muscle mass. Despite these age-related differences, resistance exercise has consistently been shown to be a highly effective stimulus for increasing skeletal muscle mass across all age groups. Furthermore, in certain populations, particularly less trained individuals, endurance training modalities may also contribute to skeletal muscle adaptations. However, endurance training alone is generally associated with less pronounced effects on SMM and may primarily be implemented to support overall health-related outcomes.