[Physical activity and aging].

About a third of the initial muscle volume is lost during human life. This decline in muscle mass is responsible for impaired muscle strength, physical frailty, falls, impaired mobility, and functional decline. The age-related loss in muscle mass accounts for the age-associated decreases in basal metabolic rate, oxygen consumption, glucose utilisation, and bone density. Several of the anatomical and physiological changes in sedentary people, commonly attributed to primary aging processes, are in fact the consequence of lack of exercise. Recent studies show that strategies to maintain muscle strength and mass among the elderly (like regular exercise training) are most important for their functional independence.