Cardiorespiratory fitness and C-reactive protein among a tri-ethnic sample of women

Background - Elevated C-reactive protein (CRP) is associated with increased coronary heart disease (CHD) risk. Cardiorespiratory fitness ("fitness") is related with lower CHD risk; however, its relationship with CRP is relatively unknown. Methods and Results - Cross-sectional associations between fitness and plasma CRP were examined among 135 African American (AA), Native American (NA), and Caucasian (CA) women (55± 11 year; 28±6 kg/m²). Fitness was assessed with a maximal treadmill exercise test. Plasma CRP concentrations were determined with the Dade Behring high-sensitivity immunoassay. Geometric mean CRP levels were 0.43, 0.25, and 0.23 mg/dL, and average maximal MET levels of fitness were 7.2, 9.1, and 10 METs for AA, NA, and CA, respectively. CRP decreased across tertiles of fitness (P=0.002), increased across tertiles of BMI (P=0.0007), and varied by race (P=0.002). After adjustment for covariates, lower CRP (P<0.05) was observed across tertiles of fitness among NA and CA, but not AA. Among all women, after adjusting for race and covariates, the odds of high-risk CRP (>0.19 mg/dL) were 0.67 (95% CI=0.19 to 2.4) among fit (>6.5 METs) versus unfit women. Conclusions - The health benefits from enhanced fitness may have an antiinflammatory mechanism.