Abstract
OBJECTIVE: The association between physical activity or cardiovascular fitness and chronic disease risk in men might be mediated, in part, through androgens. Limited data exists on the potential associations of activity or fitness with serum hormones. We examined the associations of serum testosterone and sex hormone binding globulin (SHBG) concentrations with physical activity and cardiorespiratory fitness in black and white young men. METHOD: Data were collected from 391 black and 604 white male participants of the Coronary Artery Risk Development in (Young) Adults (CARDIA) Male Hormone Study aged 24-32 in 1992-1993. Cross-sectional associations of serum total testosterone (TT), bioavailable testosterone (BT) and SHBG levels with self-reported total physical activity score, and in a subset of men (n=617) with cardiorespiratory fitness measured via duration on a treadmill test were assessed. Five-year longitudinal associations of change in hormones with changes in physical activity also were examined. RESULTS: There were no cross-sectional or longitudinal associations of physical activity with SHBG, TT or BT in either black or white men. Fitness was positively associated with SHBG only in white men, but was not associated with TT or BT in either group. CONCLUSION: Overall the results do not support an association of self-reported physical activity with androgens, whereas they do suggest that fitness might be associated with SHBG in white men.