Body Composition, Cardiorespiratory Fitness, and Low-Grade Inflammation in Middle-Aged Men and Women

The objective of the present study was to determine the respective contributions of visceral adipose tissue (AT) accumulation and cardiorespiratory fitness to variation of inflammatory markers in men and women. Circulating levels of C-reactive protein, tumor necrosis factor-α, interleukin-6, and adiponectin were obtained with visceral AT (computed tomography) and fitness (physical working capacity test) levels in a sample of healthy men (n = 120) and women (n = 152) covering a wide range of adiposity. An inflammation score was developed based on gender-specific percentile values of each inflammatory marker (0 or 1), which yielded a score ranging from 0 (low) to 4 (high). Visceral AT was positively associated with C-reactive protein and interleukin-6 levels (r ≥0.35, p <0.0001), but negatively associated with adiponectin (r = −0.29, p ≤0.0003) after adjustment for fitness. After adjusting for visceral AT, fitness was not associated with variation in inflammatory markers in women and only with adiponectin in men (r = −0.20, p = 0.03). In participants with low visceral AT (<130 cm² for men and <100 cm² for women), prevalences of participants with an increased inflammation score were 23.9% and 28.0%, respectively, for participants with high and low fitness, whereas in subjects with increased visceral AT, prevalences of a high inflammation score were 60.0% and 61.7%, respectively, for participants with high and low fitness. In conclusion, these results suggest that the previously reported association between poor fitness and low-grade inflammation may be largely attributable to increased visceral AT accumulation and its associated state of insulin resistance, conditions frequently observed in subjects with poor cardiorespiratory fitness.