Purpose: we examined the cross-sectional associations between cardiorespiratory fitness (CRF) level, different measures of adiposity, and serum 25-dihydroxyvitamin D levels (SVD) in men.
Methods: a total of 2317 men completed a baseline health examination between 2005 and 2009. Clinical measures included body mass index (BMI), waist circumference (WC), waist-to-hip ratio (W:Hip), percent body fat, CRF quantified as duration of a maximal treadmill exercise test, and measurement of SVD. Participants were classified by CRF as "unfit" (lowest 20%) and "fit" (remaining 80%) based on age as well as by clinical cut points for BMI, WC, W:Hip, and percent body fat and by categories of SVD. We examined trends of CRF and adiposity exposures across SVD categories. We also calculated odds ratios (OR) of abnormal SVD across levels of adiposity exposures before and after adjusting for CRF as well as OR of abnormal SVD across levels of CRF before and after adjusting for each adiposity exposure.
Results: we observed a significant positive trend for CRF across incremental SVD categories (P < 0.001), with the highest mean age-adjusted CRF levels (11.9 ± 1.9 METs) in the highest SVD category. When compared with normal-weight men, OR for abnormal SVD was significantly higher for overweight men within each adiposity exposure (P < 0.05). Joint associations among CRF, adiposity, and SVD revealed significantly lower SVD in unfit than in fit men within each stratum of each adiposity exposure.
Conclusions: SVD levels are positively associated with CRF and are negatively associated with different measures of adiposity in men. Higher CRF attenuates the relationship between adiposity level and SVD. Because the observed associations are cross-sectional, future prospective studies are warranted.