Combined influence of cardiorespiratory fitness and body mass index on cardiovascular disease risk factors among 8-18 year old youth: The Aerobics Center Longitudinal Study

Objective. The purpose of this study was to examine differences in cardiovascular disease (CVD) risk factors across four cross-tabulated groups of cardiorespiratory fitness and body mass index in 8- to 18-year-old children and adolescents. Methods. The sample included 296 boys and 188 girls (mean age=15.7 years) participating in the Aerobics Center Longitudinal Study. Participants were cross tabulated into four groups using a median split of age-adjusted treadmill time to exhaustion (TM) and body mass index (BMI). Group differences in CVD risk factors (blood pressure [BP], fasting total cholesterol [TC], low density lipoprotein-cholesterol [LDL-C], high density lipoprotein-cholesterol [HDL-C], TC:HDLC, triglycerides [TG], glucose, and a metabolic syndrome score) were examined by ANCOVA, controlling for age. Results. In males, significant differences across groups were observed for systolic BP, mean arterial pressure (MAP), TC, LDL-C, TC:HDL-C and the metabolic syndrome score (p<0.05). In females, only TG was significantly different across groups (p<0.05). A trend for significance was also observed for DBP and TG in males (p=0.09 to 0.11) and diastolic BP, MAP, HDL-C, and the metabolic syndrome score in females (p=0.14 to 0.16). In general, males and females in the low BMI group, either fit or unfit, had lower BP and blood lipid values than those in the high BMI group. In both sexes, the high BMI/low fit group had the highest (most adverse) metabolic syndrome score. Conclusion. This study utilized a unique approach to examine the possible interaction of fitness and fatness on CVD risk factors in children and adolescents. The results provide some evidence for the consideration of both variables when interpreting CVD risk factors in young people.