Osteoporosis, degenerative joint disease, and primary muscle atrophy are three age-related disorders of the musculoskeletal system. Osteoporosis affects 90 percent of women over 75 years, osteoarthritis afflicts 80 percent, and muscle atrophy is progressive with age. Physical conditioning retards bone loss, stabilizes deteriorated joints, and prevents muscle atrophy. The most efficient stimulus to produce these effects is therapy utilizing submaximal eccentric muscle contraction. Exercise of this type generates an equivalent training effect with less energy expenditure and less cardiovascular stress.There are presently no isotonic eccentric devices available to study exercise in which the resistance in the lifting phase of the cycle can be different from the resistance during the lowering phase. Phase I will involve development of a mechanism with which eccentric muscle conditioning can be performed. The application of the principles learned from this project may increase function and activity for postsurgical patients, neurologically impaired individuals, and the elderly.National Institute on Aging (NIA)
