Lack of association of anabolic hormone status and muscle strength with regional and whole body bone mineral density in healthy men aged 60-79 years

This study investigated the capacity of muscle strength and anabolic hormon e status to predict regional and whole body bone mineral density (BMD) in o lder men. Fifty-two healthy men aged 60-79 years served as subjects. BMD of the lumbar spine, proximal femur, upper and lower limbs, and whole body wa s assessed by dual Xray absorptiometry. Dynamic muscle strength for several upper and lower body muscle groups was determined by the one-repetition ma ximum and isometric grip strength by dynamometry. Anabolic hormone status w as assessed by the ratio of testosterone (T) to sex hormone binding globuli n (SHBG), given as the free androgen index (FAI), and the ratio of insulin- like growth factor I (IGF-I) to IGF binding protein-3 (IGFBP-3). Age was as sociated with declines in dynamic strength and the log FAI. In stepwise reg ression analysis, only body mass was an independent predictor of whole body and upper limb BMD (R-2=0.14), and hip adductor strength predicted the War d's triangle (R-2=0.13). For lumbar spine BMD, triceps extensor strength te as significantly correlated (r=0.36, p<0.01), while no strength or hormonal variable was associated with the femoral neck, trochanter, or lower limb. The lack of association between muscle strength and BMD was generally unalt ered after controlling for hormone status and body mass. There was no diffe rence in BMD when analyzed by tertiles of log FAI or IGF-I/IGFBP-3 or by te rtiles of muscle strength. These results suggest that in healthy community- dwelling men in the seventh and eighth decade, muscle strength and hormonal status are not significant contributors to regional or whole body BMD.