Caractéristiques du vieillissement musculaire et effets préventifs de l'exercice régulier

Abstract

Aims This paper was aimed to present the current knowledge concerning the clinical aspects of sarcopenia, its mechanisms, as well as the role played by regular exercise on the potential health problems such as impairments in mobility and activities of daily living. Current knowledge Muscle ageing is associated with a marked decrease in muscle mass, muscular performances, and with an increase in muscle fatigability. The mechanisms of sarcopenia remain largely unknown; the decrease in muscle mass appears to be related to an alteration of protein metabolism with a decrease in protein synthesis which mainly affects contractile proteins and the fast myosin isoforms. This alteration in protein metabolism directly affects the myofiber size. An age-related loss of myofibers also contributes to explain muscle wasting, especially related to an impairment of the control of satellite cell activation and proliferation. These alterations may participate in the accumulation of repeated episodes of incomplete repair and regeneration, thus contributing to the loss of skeletal muscle mass and function with aging. A reduction in mitochondrial number and activity might account for muscle fatigability. Deletions, rearrangements, or DNA damage accumulated over time contribute to explain reduced mitochondrial protein synthesis and oxidative enzyme activity. Both regular strength and endurance exercises have provided some of the most promising data for prevention of muscle loss and fatigability. Physical exercise programs have been shown to increase muscle protein synthesis rate, and enhance oxygen diffusion and use by peripheral tissue. Future prospects Future studies are needed to examine the specific effects of several kinds of exercise programs on muscle mass, structure and function.