SKELETAL-MUSCLE MECHANICS IN OSTEOPOROTIC AND NONOSTEOPOROTIC POSTMENOPAUSAL WOMEN

The purpose of this study was to evaluate single-joint, dynamic muscle function of osteoporotic (OST) and nonosteoporotic (N-OST) women. Kne e flexor and extensor function in postmenopausal women (6th decade OST , n=15; 7th decade OST, n=10; 6th decade N-OST, n=6; 7th decade N-OST, n=5) were evaluated at five angular velocities from 60 degrees.s(-1) to 300 degrees.s(-1). All subject groups had similar anthropometric me asurements, but the 6th decade N-OST group were more physically active than the age-matched OST group. The OST and N-OST women produced peak torque at similar knee angles. The 6th decade N-OST women produced si gnificantly greater knee extensor mean peak torque and angle specific torque, and mean work than any of the other three groups (P<0.05). How ever, knee flexor function was equivalent throughout the groups for mo st comparisons, except those between the 6th decade N-OST and 7th deca de OST. While previous research has shown an early loss of flexor musc le function in ageing women, our data indicated that women with osteop orosis also experience a deterioration in quadriceps muscle function n ot encountered within the N-OST subjects. It is possible that such a c hange is precipitated by reduced physical activity, and may mirror det erioration in bone mineral content.