Purpose: The purpose of this study was to examine the relative association of physical activity, cardiorespiratory fitness (CRF), and adiposity with C-reactive protein (CRP) in prepubescent children.
Methods: Forty-five prepubescent children (age = 9.4 ± 1.6 yr; 26 boys) were assessed for adiposity (percent fat) via dual-energy x-ray absorptiometry, CRF with a peak graded exercise test, physical activity using pedometers, and systemic inflammation via serum CRP.
Results: Adiposity was positively correlated with CRP (body mass index, r = 0.61; percent fat, r = 0.59, P < 0.001), whereas step count and CRF were inversely associated with CRP (r = -0.49 and -0.37, respectively, all P values < 0.05). Compared across fitness or physical activity and adiposity groups, the low-fit/high-fat and the low-activity/high-fat groups had higher CRP than both low-fat groups. There was also a main effect of physical activity (P < 0.01) but not fitness on CRP. Regression analyses revealed that percent fat (ß = 0.59, P = 0.002) and physical activity (ß = -0.35, P = 0.011) were the only independent predictors of CRP, explaining 16.0% and 10.0% of the variance, respectively.
Conclusions: Adiposity is positively related to serum CRP in prepubescent children, independent of the effects of fitness or physical activity. In addition, physical activity is inversely associated with CRP levels. This research identified habitual physical activity and adiposity as focal points for the design of interventions attempting to reduce chronic systemic inflammation in children.