Ageing sarcopenia : a systemic or peripheral phenomenon?

Sarcopenia is the exacerbated loss of skeletal muscle mass, decline in muscle strength, and the concomitant increased disability and mortality frequently associated with chronic pathologies, and aging. The aetiology of this syndrome is multifactorial, and includes changing of endocrine function, chronic diseases, inflammation, and nutritional disorders, however aging and muscle deconditioning caused by reduced physical activity plays a determinant role in this phenomenon. For instance, in both men and women, the reduction in skeletal muscle mass is greater in the lower limbs (15%) respect to the upper limbs (10%) which may seem counterintuitive when considering the bipedal nature of human locomotion. However, given that physical activity is significantly and progressively reduced during the lifespan, even in fully independent older individuals, the greater loss of muscle mass in the lower limbs may be primarily due to a local deconditioning effect. In contrast, the arms are consistently utilized for the activities of daily living across the lifespan, and consequently this recognized inactivity-driven reduction in skeletal muscle is less pronounced in the upper limbs. Therefore, with the recognition of regional changes of muscle mass, particularly of those muscles essential for human locomotion, it appears that sarcopenia can be considered a peripheral phenomenon, instead of a systemic occurrence.