Role of satellite cells on muscle hypertrophy and muscle in response to exercise

Abstract

Since the discovery of the satellite cells in 1961 a number of studies have examined the role that these cells play on muscle hypertrophy and regeneration, and on the hypertrophy response to strength training in humans. The interest for these cells has raised in the last years due to the fact that they could be used as a vehicle in techniques of cellular therapy. The following review describes some of the elicited by physical activity on the satellite cells and how these satellite cells may contribute to muscle hypertrophy and regeneration. The content of nuclei pertaining to satellite cells among the overall nuclei content in a muscle histological preparation ranges between 1 and 7%. Regular physical activity has been associated with both and enhancement of the total number of nuclei and increase of the content of satellite cells. In contrast, ageing is associated with a reduced proportion of nuclei pertaining to satellite cells. The latter, may be attenuated by regular participation on exercise, although there is no definitive scientific evidence for this effect. Anabolic steroid abuse has been associated with increased content of satellite cells in bodybuilders. It remains unknown, however, what the kind, duration and intensity of exercise more appropriate to stimulate satellite cell activation, proliferation and differentiation. Less is even known about the mechanisms that govern the process of fusion and incorporation of satellite cells with pre-existing muscle fibers, although some experimental evidences suggest that this process is facilitated by regular physical activity. More studies are need to verify if the combination of myotrauma (sport injury, for example) and exercise during the recovery phase after an injury results in a greater stimulation of the f the satellite cells and in a more efficient reparation.