MUSCLE STRENGTH AND BODY-COMPOSITION - ASSOCIATIONS WITH BONE-DENSITYIN OLDER SUBJECTS

This study investigated the relationship between isokinetic muscle str ength and bone density (SPA and DPA) in men and women aged 45-77 yr. R egression models were adjusted for age, weight, smoking status, and ca lcium supplementation. Elbow extensors (but not flexors) peak torque w as correlated with radial density in men (partial r = 0.26, P < 0.05) and women (partial r = 0.24, P < 0.05). Knee flexor (but not extensor) peak torque in women was significantly correlated with spine density (partial r = 0.28, P < 0.05), and muscle mass was significantly correl ated with Ward's triangle density (partial r = 0.35, P < 0.05). No ass ociations between knee flexor or extensor muscle strength and spine or femur bone density were observed in men. Fat-free mass (FFM, hydroden sitometry) was associated with all bone density sites in males and fem ales (partial r = 0.30-0.55; P < 0.05). These results demonstrate that 1) significant associations observed between elbow extensor strength and radial bone density in men and women may reflect loading along the longitudinal axis of the radius associated with elbow extensor activi ty; and 2) significant associations exist between knee flexor muscle s trength and lumbar density in women only. Additionally, the associatio ns between FFM and bone density do not necessarily reflect association s between isokinetic muscle strength and bone density.