Human neuromuscular aging: Sex differences revealed at the myocellular level

Age-related muscle loss (sarcopenia) is a major clinical problem affecting both men and women – accompanied by muscle weakness, dysfunction, disability, and impaired quality of life. Current definitions of sarcopenia do not fully encompass the age-related changes in skeletal muscle. We therefore examined the influence of aging and sex on elements of skeletal muscle health using a thorough histopathological analysis of myocellular aging and assessments of neuromuscular performance. Two-hundred and twenty-one untrained males and females were separated into four age cohorts [mean age 25 y (n = 47), 37 y (n = 79), 61 y (n = 51), and 72 y (n = 44)]. Total (−12%), leg (−17%), and arm (−21%) lean mass were lower in both 61 y and 72 y than in 25 y or 37 y (P