For the last two decades, considerable interest has been directed to the loss of muscle mass that occurs with aging, defined as sarcopenia. The conceptual model of sarcopenia posits that a low skeletal muscle mass leads to a decrease in muscle strength. A decrease in strength affects physical performance and is thought to precede physical disability. However, recent work suggests that loss of muscle strength may precede or follow the loss of lean muscle mass, and is more strongly linked to adverse consequences than lean muscle mass alone. Several investigators have proposed that the loss of muscle strength (with or without loss of muscle mass) be defined as dynapenia and separated from the more limited term sarcopenia, which implies only the loss of lean muscle mass. A therapeutic approach to the loss of skeletal muscle mass and strength in older persons depends on the correct classification. The term sarcopenia should be reserved for age-related decline in muscle mass that is not attributable to the presence of proinflammatory cytokines. Cachexia may be a better term for a decline in muscle mass associated with known inflammatory disease states. Although starvation resulting from protein energy undernutrition is widely regarded as the primary cause of loss of fat and fat-free mass in older persons, a failure to improve with nutritional replacement should trigger a consideration of other causes. Advances in understanding of sarcopenia suggests that resistance exercise training and nutritional supplementation can improve both muscle strength and muscle mass. This symposium described practicalities for integrating nutritional and physical therapy to strengthen physical function.