This study examined cardiac and arterial differences between overweight and normal-weight preadolescent children. Twenty children (10.2 +/- 0.4 years of age) classified as overweight, on the basis of age-appropriate body mass index (BMI) cutoffs, were compared with 43 normal-weight controls. Height, mass, and body surface area were measured. Relative body fat and lean body mass were estimated from skinfold thickness. Each child's weekly physical activity metabolic equivalent (PAME) was calculated using a standardized questionnaire, and his or her sexual maturation was self-assessed using the Tanner scale. Peak aerobic power was assessed using a cycle ergometer and normalized to lean body mass. Mean arterial pressure was calculated from systolic and diastolic blood pressure (DBP) measurements taken with a Finapres. Cardiac dimensions were measured, using Mu-mode 2-dimensional echocardiography, and normalized to body surface area and height2.7. Left carotid artery pulse pressure (CaPP) was assessed with applanation tomometry. Overweight boys and girls had a higher left ventricular mass (LVM) and LVMHT2.7 than normal-weight boys and girls. CaPP was signficantly lower in the overweight than in the normal-weight groups, whereas PAME and relative peak aerobic power were significantly higher in the boys than the girls. Although overweight children had significantly higher stroke volumes and cardiac outputs than normal-weight children, ejection fraction was similar in the weight groups. Adjusted LVMHT2.7 was associated with cardiac volume measurements, BMI, and DBP in normal-weight children, whereas in the overweight children LVMHT2.7 did not significantly correlate with any variable. In conclusion, we found that cardiovascular adaptations can be seen in prepubescent overweight children as young as 10 years of age.