Skeletal muscle apoptosis in aging and exercise

Sarcopenia is the loss of muscle mass and function that occurs in the normal course of aging. Mechanisms contributing to the pathogenesis of sarcopenia are not yet clearly defined, but are likely to involve activation of proteolytic pathways, which may be in response to oxidative stress, inflammation, hormonal adaptations, and loss in neurological innervations. Recently investigated mechanisms include activation of apoptotic signaling pathways, which may include the mitochondrial-mediated, receptor-mediated, and/or sarcoplasmic reticulum-mediated pathways. The activation of proteolytic pathways, including apoptotic processes, may be partly responsible for the initiation of muscle protein degradation, loss of muscle nuclei associated with local atrophy, and death of specific myocytes during aging. Exercise is an effective intervention to enhance muscle mass and function and may result in favorable adaptations to prevent apoptosis. Little is known about the effects of exercise on apoptosis and proteins involved with its signaling and activation. Current research regarding the potential role of apoptosis in skeletal muscle homeostasis during aging and exercise is discussed.