Stuart M. Phillips

The maintenance of a metabolically active skeletal muscle mass is to a great extent underappreciated, particularly where optimal health is concerned. Skeletal muscle, besides its obvious role in locomotion, is a highly important thermogenic (i.e., energy consuming) tissue and the prime determinant of our basal metabolic rate, which for most of us is the largest single contributor to daily energy expenditure. Hence, declines in skeletal muscle mass can lead to increases in body fat mass. Because of its oxidative capacity (i.e., mitochondrial content) skeletal muscle is also a large site of fat oxidation, potentially playing a role in maintaining lipoprotein (cholesterol) and triglyceride homeostasis. Skeletal muscle is also, mostly by virtue of its mass, the primary site of blood glucose disposal; hence, maintaining skeletal muscle mass would also play a role in reducing risk for development of type II diabetes. Finally, the decline in maximal aerobic capacity with age, and with other metabolic disorders.