The effects of exercise on skeletal muscle in the aged.

Age-related sarcopenia leads to muscle weakness and a concomitant increase in gait problems and the risk of hip fracture due to falling in the elderly. Muscle weakness reduces general activity levels in elderly individuals which in turn elevates the risk of osteoporosis due to a decrease in overall mechanical loading of the skeleton. At the same time, age-related sarcopenia is also linked to an increase in the risk of metabolic disorders such as adult onset (Type II) diabetes. However, it is widely accepted that increased mechanical loading of the musculoskeletal system (e.g., resistive exercise) can have a beneficial effect on both skeletal muscle and the supporting skeleton resulting in a significant reduction in the risk of developing all of the above age-related problems. As such, unloading models that exhibit many if not all of the same responses observed in aged muscle, including the capacity of exercise to reverse these responses, may provide valuable insight into the skeletal muscle aging process.