Age-related changes in muscle.

Sarcopenia is a debilitating condition that occurs with senescence. The present study places this entity in the context of life expectancy, then discusses the mechanism of muscle loss. The findings show deficits in muscle protein synthesis with advancing age and suggest that these deficits are specific to certain muscle protein components. Synthesis rates of myosin heavy chain and mitochondrial protein decline with advancing age; however, there are no specific conclusions as to causation of these reduced muscle protein syntheses. The utility of protein dynamic measurements in evaluating potential therapies is discussed.