C-REACTIVE PROTEIN AND CARDIORESPIRATORY FITNESS IN AN ADULT POPULATION

Abstract

Elevated C-reactive protein (CRP), a hepatic marker of sub-clinical inflammation, is associated with coronary heart disease (CHD) risk. Preliminary data suggest an inverse correlation between CRP and cardiorespiratory fitness (CF), however data are sparse. PURPOSE To determine the cross-sectional association between plasma CRP and CF among a healthy, adult population. METHODS Plasma CRP and CF were examined in a sub-sample of 46 adults (26 males, 20 females) aged 23–64 yrs (BMI: 27.0 ± 5.5 kg/m2) who completed a coronary risk factor screening at the University of South Carolina. Plasma CRP was quantified using a high sensitivity enzyme linked immunosorbent assay. CF was measured with a maximal treadmill exercise test and used to dichotomize participants as high fit (HF) (> 20th percentile of age- and gender-specific maximal treadmill time) and low fit (LF) (20th percentile of age- and gender-specific maximal treadmill time). RESULTS CRP concentration did not vary by gender, categories of body mass index, diabetes status, or smoking status. CRP correlated significantly (p < 0.05) with low-density lipoprotein cholesterol (r = 0.41), triglyceride (TG) (r = 0.43), and total cholesterol (r = 0.36) concentrations. Maximal MET levels of fitness were 12.4 and 9.4 METS for the HF and LF groups, respectively. Geometric mean CRP concentration varied significantly (p = 0.036) by fitness level (0.15 and 0.43 mg/dl for the HF and LF groups, respectively), however, significance disappeared after adjustment for TG concentration. CONCLUSION A significant trend for lower CRP concentration among adults with higher CF existed. This trend continued after adjustment for TG concentration, however, results were not statistically significant. Lack of statistical significance may be attributed, in part, to a small sample size and a rather healthy, homogeneous population. The clinical relevance of our findings support the conclusion that the health benefits attained from enhanced CF may have an anti-inflammatory mechanism.