Fatness, Fitness, and Increased Cardiovascular Risk in Young Children

Objectives To investigate the relationships between cardiorespiratory fitness and adiposity among young children, and their influence on a comprehensive cardiovascular risk profile. Study design The sample included 95 healthy weight, 54 overweight, and 31 obese children (n = 180, 10.9 +/- 2.1 years). All children had a medical assessment that included a physical examination and fasting investigations including glycated hemoglobin, total cholesterol, high-density lipoprotein, low-density lipoprotein, triglycerides, insulin and glucose levels. Body mass index and waist circumference z-scores were calculated. Children's fitness level was measured with the Queens College step test. Results Although low fitness was independently associated with cardiovascular risk, multi-level analysis demonstrated that waist circumference z-score was the only significant predictor of cardiovascular risk factors including SBP (beta = 3.29, P <.001), DBP (beta = 1.88, P <.005), high-density lipoprotein (beta = -0.12, P <.001), and triglyceride levels (beta = 0.14, p <.001), fasting insulin (beta = 2.83, P <.001), C-peptide (beta = 0.11, P <.001), and HOMA-IR (beta = 0.34, P <.001), with increasing waist circumference z-score associated with increasing cardiovascular risk. Within the healthy weight children, high fitness was associated with significantly reduced triglyceride levels, and lower fasting glucose, insulin and HOMA-IR. Conclusions Young children's health may be influenced more by body fatness, and in particular, the distribution of body fat than by cardiorespiratory fitness. However, within the healthy weight children, high fitness was associated with a favorable metabolic profile, suggesting that cardiorespiratory fitness may exert a protective effect on metabolic risk in children whose risk is not confounded by fatness. (J Pediatr 2010; 157:552-8).