[Physical activity to delay the effects of aging on mobility]

SARCOPENIA: Aging is accompanied by the progressive reduction in cardio-pulmonary capacity and muscular strength. These two phenomena are partly related to the decrease in muscle mass, or sarcopenia. CARDIO-PULMONARY CAPACITY: Measured by maximum oxygen consumption (VO2max), it demonstrates the individual's capacity for movement. It is also the principle marker of mortality due to cardiovascular events. VO2max decreases by around 0.8% each year, in close correlation with the evolution in muscle mass. These phenomena are partly related to reduced physical activity and, particularly, intense activity greater than 6 MET. Regular practice of moderately intense physical activity can maintain VO2max at a level 20 to 35% superior to that of the mean level in the same age range, and is associated with increased autonomic nervous system activity. DECREASED MUSCULAR STRENGTH: Sarcopenia and the proportional decrease in fast-twitch muscle fibers are related to a reduction in physical activity. The decrease in muscular strength is a handicapping factor and increases the risk of falls. Two sessions of training per week can increase by more than 30% the strength of the muscles concerned, by increasing the muscle volume and the maximum frequency of emission of motoneuron influx. The production of somatotropin, insulin-like growth factor-I and testosterone can also be increased. High-resistance exercises are themselves sufficient to increase bone density. In the light of these advantages, the practice of workouts in endurance and strength should be encouraged.