Sarcopenia of male aging

Sarcopenia is a common consequence of aging, with onset as early as the fourth decade. The decline in muscle strength is approximately 1% per year and is associated with loss of muscle mass and decreased muscle quality. At the cellular level, this loss of muscle function is associated with declines in muscle protein synthesis and mitochondrial capacity. Resistance strength training has the most substantive evidence in reversing sarcopenia, although aerobic exercise may also be beneficial. Both resistance and aerobic exercise enhance mixed muscle protein synthesis, although resistance training has a more profound stimulatory effect. It is likely that different exercise regimens may have distinctive effects on particular muscle proteins, suggesting the importance of variety in exercise. 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. Much has been accomplished in studying the pathophysiology behind sarcopenia. Much still remains in altering its course.