Objective: Cardiorespiratory fitness and obesity, especially central adiposity, have consistently been associated with circulating C-reactive protein (CRP), particularly in aging women. The purpose of this study was to determine the sex-specific independent relationships between physical activity, fitness, central and whole body adiposity, and CRP in sedentary older adults.
Design: Cross-sectional study on sedentary, healthy, community-dwelling older adults (age, mean +/- SD; 70.0 +/- 5.4 years; N = 132, 47 men, 85 women). Physical activity was determined using a questionnaire, fitness using a maximal oxygen consumption treadmill test (V(dot)O2peak), and body composition via dual-energy x-ray absorptiometry.
Results: CRP tended to be higher in women than men (4.0 +/- 2.9 vs 3.1 +/- 2.3 mg/L, P = 0.07). All measures of adiposity (absolute, relative [%fat], and trunk) were positively associated with CRP in women (r range = 0.22-0.28, all P < 0.05), whereas neither physical activity nor fitness was related. In contrast, %fat was the only measure of adiposity associated with CRP in men (r = 0.36, P = 0.01) and V(dot)O2peak was inversely correlated with CRP (r = -0.31, P = 0.04). Trunk fat was the only independent predictor of CRP in women, explaining 8% of the variance (P = 0.01), whereas %fat (P = 0.01) and anti-inflammatory medication use (P = 0.02) were independent predictors of CRP in men, explaining 13% and 10% of the variance, respectively.
Conclusions: In sedentary, healthy older adults, the relationship between regional body fatness, aerobic fitness, and CRP differs between sexes such that (1) central adiposity was most strongly associated with CRP in women, whereas %fat was the strongest predictor of systemic inflammation in men and (2) the negative association between fitness and CRP was stronger in men.