Sarcopenia: a major modifiable cause of frailty in the elderly.

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.