Chief, Nutrition, Exercise Physiology, and Sarcopenia (NEPS) Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Associate Professor, Tufts University. Correspondence to Dr. Roubenoff at NEPS Laboratory, USDA HNRCA, 711 Washington Street, Boston, MA 02111, USA. Telephone 617-556-3172; fax 617-556-3083 o e-mail at roubenoff@hnrc.tufts.edu. o The contents of this publication do not necessarily reflect the views or policies of the U.S. Department of Agriculture, nor does mention of trade names, commercial products, or organizations imply endorsement by the United States government.

Abstract: Sarcopenia is the loss of muscle mass and strength that occurs with aging. It is a consequence of normal aging, and does not require a disease to occur, although muscle loss can be accelerated by chronic illness. Sarcopenia is a major cause of disability and frailty in the elderly. There are many candidate mechanisms leading to sarcopenia, including age-related declines in alpha-motor neurons, growth hormone production, sex steroid levels, and physical activity. In addition, fat gain, increased production of catabolic cytokines, and inadequate intake of dietary energy and protein are also potentially important causes of sarcopenia. The relative contribution of each of these factors is not yet clear. Sarcopenia can be reversed with high-intensity progressive resistance exercise, which can probably also slow its development. A major challenge in preventing an epidemic of sarcopenia-induced frailty in the future is developing public health interventions that deliver an anabolic stimulus to the muscle of elderly adults on a mass scale.

Key words: sarcopenia, frailty, elderly, treatment, prevalence