NEW ORLEANS — Fatness has more influence than does fitness on cardiovascular disease risk in children and adolescents, data from the Cardiovascular Health in Children and Youth II and III studies show.
The findings suggest that interventions to reduce cardiovascular disease risk should begin early in youth and should focus on reducing body fat, reported Kristin S. Ondrak in a poster at the annual meeting of the American College of Sports Medicine.
Ms. Ondrak and her colleagues used baseline information from a total of 1,824 participants in the CHIC studies, including 938 girls and 886 boys aged 8–16 years, for the current analysis. They assessed fatness and fitness for each participant, as well as cardiovascular disease risk.
Fatness in this study was assessed using the sum of skin folds at the triceps and subscapular sites, and was calculated using established equations that factor in gender, race, and pubertal status. Fitness (defined as aerobic power, or peak oxygen intake [VO2max], and here expressed in mL/kg per minute as kgVO2max) was estimated using a multistage submaximal test on a cycle ergometer, with a workload corresponding to a heart rate range of 150–170 beats per minute used to predict the maximum intake. The kgVO2max measurement includes fat mass, so the researchers also calculated the aerobic power per kilogram of fat-free mass (ffmVO2max) to remove the potentially confounding effect of fat mass.
The cardiovascular risk score was based on measurements of HDL cholesterol, total cholesterol, triglycerides, systolic and diastolic blood pressures, and fasting insulin, with each measurement classified into one of three risk categories and assigned a score (0 = no risk, 1 = borderline risk, 2 = at risk); the sum of a participant's scores represented that individual's total cardiovascular risk score.
After adjustment for gender and socioeconomic status, the percentage of body fat was a stronger predictor of cardiovascular disease risk score than was fitness, with fatness accounting for the majority of variance in total risk score in each of three age groups (8–10 years, 11–13 years, and 14–16 years).
This was particularly true for the youngest group (partial R
Although fatness played a greater role in risk in the youngest age group in this study, it was the 11- to 13-year age group that appeared most vulnerable, because this group had significantly higher cardiovascular risk scores than did the other groups, and also had more risk factors that were classified as “borderline risk” and “at risk” than did the other groups.
Although the mean percentage of body fat was high for boys and girls in each age group (18% for boys and 27% for girls in the 8- to 10-year age group; 21% for boys and 29% for girls in the 11- to 13-year age group; and 16% for boys and 32% for girls in the 14- to 16-year age group), and the mean aerobic power was low (kgVO2max of 40 for boys and 34 for girls in the 8- to 10-year age group; 41 for boys and 34 for girls in the 11- to 13-year age group; and 41 for boys and 31 for girls in 14- to 16-year age group), the percentages of participants with elevated risk scores (scores greater than 6 out of 12 possible points) was low (mean of 1.5 boys and 1.8 girls in the 8- to 10-year age group; 2.5 boys and 2.7 girls in the 11- to 13-year age group; and 1.7 boys and 1.5 girls in the 14- to 16-year age group). (See box.)
Fatness and fitness have been implicated in the increasing prevalence of cardiovascular disease risk factors in children and adolescents, but which variable is more important in determining risk and whether age plays a role have remained controversial questions. Some data suggest that a higher percentage of body fat is associated with increased risk regardless of fitness levels, and other data suggest high fitness levels are associated with a lower percentage of body fat. The current study is the first to examine the influence of age in the roles that fitness and fatness play in cardiovascular risk, Ms. Ondrak noted.
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