Weight-Independent Cardiovascular Fitness and Coronary Risk Factors

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Abstract
Background: It is unclear whether cardiovascular fitness influences risk factors for coronary artery disease and non-insulin-dependent diabetes mellitus independently of level of body fat because fitness is often measured in tasks that involve moving body weight (eg, running) and because body weight and level of body fat are correlated. Objective: To measure fitness during a task in which body weight was controlled experimentally (ie, supine cycling). Design: Cross-sectional. Participants: Seventy-four children, 7 to 13 years of age, recruited through school flyers and newspaper advertisements, varying in level of body fat from 7% to 61%. There were 31 boys and 43 girls; 35 were white and 39 were black. Main Independent Variables: Cardiovascular fitness was expressed as submaximal heart rate while cycling at a power output of 49 W, and level of body fat was measured with dual x-ray absorptiometry. Main Outcome Measures: Blood pressure and levels of triglycerides, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, insulin, glucose, and glycohemoglobin. Results: Controlling for age and sex, level of body fat was significantly (P<.01) related to unfavorable levels of systolic blood pressure (r=0.32), triglycerides (r=0.42), high-density lipoprotein cholesterol (r= −0.31), insulin (r=0.50), and total cholesterol to high-density lipoprotein cholesterol ratio (r=0.37); submaximal heart rate was not significantly correlated with any of the other variables. Conclusions: When cardiovascular fitness was measured in a weight-independent task, it was not significantly related to level of body fat or the major coronary artery disease and non–insulin-dependent diabetes mellitus risk factors. In addition, we confirmed previous findings that higher levels of body fat are associated with a very unfavorable risk profile. Arch Pediatr Adolesc Med. 1997;151:462-465