OBJECTIVES: To examine the association between aging and physical function in men by testing a theoretically based model of aging, hormones, body composition, strength, and physical function with data obtained from men enrolled in the Boston Area Community Health/Bone (BACH/Bone) Survey.
DESIGN: Cross-sectional, observational survey.
PARTICIPANTS: Eight hundred ten black, Hispanic, and white randomly selected men from the Boston area aged 30 to 79.
MEASUREMENTS: Testosterone, estradiol, sex hormone–binding globulin, lean and fat mass, grip strength, and summated index of physical function (derived from walk and chair stand tests).
RESULTS: Measures of grip strength and physical function declined strongly with age. For instance, 10 years of aging was associated with a 0.49-point difference (scale 0–7) in physical function. Age differences in total testosterone and estradiol concentrations were smaller than age differences in their free fractions. Weak or nonsignificant age-adjusted correlations were observed between hormones and measures of physical function, although path analysis revealed a positive association between testosterone and appendicular lean mass and a strong negative association between testosterone and total fat mass. Lean and fat mass, in turn, were strongly associated with grip strength and physical function, indicating the possibility that testosterone influences physical function via indirect associations with body composition.
CONCLUSION: The age-related decline in serum testosterone concentration in men has a weak association with physical strength and functional outcomes through its associations with lean and fat mass.