Physical activity, cardiovascular fitness, and adiposity in children.

With cardiovascular fitness (CVF) as the dependent variable, relationships with habitual level of physical activity, age, gender, and body mass index (BMI) were investigated in a sample of 93 high adiposity and 93 low adiposity children, ages 8 to 13. A physical activity score (PAS) was computed for each child from a 2-day observation period. A physical working capacity index from cycle ergometry (PWC170) was the measure of CVF. Low and high adiposity samples were classified by a median split (42.9 mm) on the sum of three skinfold measures (tricep, suprailiac, subscapula). For the high adiposity sample, PAS, age, BMI, and gender were significant and the overall model was significant (p less than .001), accounting for 38% of variance in PWC170. In the low adiposity sample, gender (p less than .04) was significantly related to CVF, but the overall model was not significant (p less than .35). PAS, thus, was a significant predictor of CVF among the high adiposity children, but not the low adiposity children. Mechanisms that may account for this difference include greater work for equal activity among the obese, a ceiling effect on CVF among the low adiposity children, or differences in hormonal or metabolic factors mediating the activity-CVF relationship.