Significance

Sarcopenia, or aging-associated muscle atrophy, increases the risk of falls and fractures and is associated with metabolic disease. Because skeletal muscle is a major contributor to glucose handling after a meal, sarcopenia has significant effects on whole-body glucose metabolism. Despite the high prevalence and potentially devastating consequences of sarcopenia, no effective therapies are available. Here, we show that treatment of mice with an anti-myostatin antibody for just 4 wk increased muscle mass and strength in both young and old mice. In old mice, this increase in muscle mass was accompanied by an improvement in muscle insulin sensitivity. These data provide support for myostatin inhibition as a potential therapeutic strategy for aging-associated sarcopenia and insulin resistance.