Sarcopenia of male aging

Sarcopenia is a common consequence of aging with onset as early as the fourth decade. At the cellular level, this loss of muscle function is associated with declines in muscle protein synthesis and mitochondrial capacity. Resistance and aerobic exercise enhance mixed muscle protein synthesis, although resistance training has a more profound stimulatory effect. Although increased age and declining muscle function are associated with decreased testosterone levels in men, the role of testosterone supplementation remains controversial. Strong evidence exists for testosterone increasing muscle mass and muscle protein synthesis, yet a clear increase of muscle strength in elderly people by testosterone has not been observed, an observation vulnerable to confounding factors and experimental design.