Association between hs-CRP, Leisure-time Physical Activity and Body Weight in Children

Abstract

C-reactive protein (CRP) concentration is a novel risk marker for cardiovascular disease. Exercise training has been shown to reduce CRP concentration in adults. PURPOSE: To study if physically active children have lower CRP concentration than sedentary children. Additionally to study the association of CRP with body weight. METHODS: This study is a part of the large prospective randomized STRIP study (Special Turku Coronary Risk Factor Intervention Project) on-going in Turku, Finland. Leisure-time physical activity habits were assessed during a study visit at age 13 (n=565) by a self-reported questionnaire. Leisure-time physical activity index (PAI; MET h/wk) was calculated by leisure-time exercise intensity, duration and frequency (n=558: 294 boys, 264 girls). According to PAI the girls and boys were divided into 3 groups: 1) Sedentary, mean PAI 3.1 for girls (n=89) and 8.2 for boys (n=114) 2) Average Active, mean PAI 24.7 (n=121) and 30.7 (n=89), respectively and 3) Active, mean PAI 54.8 (n=54) and 58.7 (n=91), respectively. High-sensitivity C-reactive protein (hs-CRP) concentration (n=532) was assayed by a turbidimetric immunoassay (Wako Chemicals GmbH, Neuss, Germany). The sensitivity of the method was 0.06 mg/L. Concentration under the detection limit was interpreted as 0.05 mg/L (n=14) and concentration >10 mg/L as 10.0 mg/L (n=4). Due to the skewed distribution of the hs-CRP concentrations, log-transformation was used. ANCOVA with BMI as a covariate was used to test the differences in hs-CRP between the groups. T-test was used to compare overweight boys (BMI >21.9, 16%) and girls (BMI >22.6, 14%) to children with normal body weight. RESULTS: Physically active 13-year-old children had similar hs-CRP concentration to Sedentary and Average Active children. The mean (median) hs-CRP concentration in the Sedentary, Average Active and Active boys was 0.75 (0.23), 0.58 (0.21) and 0.46 (0.19) mg/L, respectively (NS). In girls the corresponding concentrations were 0.42 (0.19), 0.52 (0.16) and 0.44 (0.20) mg/L (NS). Overweight children were found in all 3 activity groups. Interestingly, overweight girls and boys had higher (p <0.0001) mean hs-CRP concentration (1.31 and 1.29 mg/L, respectively) than girls and boys with normal body weight (0.32 and 0.47 mg/L, respectively). CONCLUSION: Physically active 13-year-old children have similar hs-CRP concentration to sedentary children. It is evident that physical activity and body weight have interesting and challenging interrelations.