The influence of cardiorespiratory fitness on clustered cardiovascular disease risk factors and the mediator role of body mass index in youth: The UP&DOWN Study

Background The combined effect of cardiorespiratory fitness (CRF) and body mass index (BMI) on cardiovascular disease (CVD) risk in young people remains to be fully determined. We examined the individual and combined associations of CRF and BMI with clustered CVD risk factors, and the mediator role of BMI in the association between CRF and clustered CVD risk factors in children and adolescents. Methods 237 children (111 girls) and 260 adolescents (120 girls) were included in this cross‐sectional study. Height and weight were assessed and BMI was calculated. A CVD risk factor index (CVDRF‐I) was computed from: waist circumference, systolic blood pressure, triglycerides, high‐density lipoprotein cholesterol and glucose. CRF was assessed using the 20‐m shuttle run test. Regression analysis, analysis of covariance and mediation analysis (Baron and Kenny procedures) were used to test the independent and combined effect of CRF and BMI on CVDRF‐I, and to test mediation hypothesis, respectively. Results CRF was negatively associated with CVDRF‐I (all P