Background:Little is known about how the intensity of exercise influences cardiovascular fitness and body composition, especially in obese adolescents. Objective: Our goal was to determine the effects of physical training intensity on the cardiovascular fitness, percentage of body fat (%BF), and visceral adipose tissue (VAT) of obese adolescents. Design: Obese 13-16-y-olds (n = 80) were assigned to 1) biweekly lifestyle education (LSE), 2) LSE + moderate-intensity physical training, or 3) LSE + high-intensity physical training. The intervention lasted 8 mo. Physical training was offered 5 d/wk, and the target energy expenditure for all subjects in physical training groups was 1047 kJ (250 kcal)/session. Cardiovascular fitness was measured with a multistage treadmill test, %BF with dual-energy X-ray absorptiometry, and VAT with magnetic resonance imaging. Results: The increase in cardiovascular fitness in the highintensity physical training group, but not in the moderate-intensity group, was significantly greater than that in the LSE alone group (P = 0.009); no other comparisons of the 3 groups were significant. Compared with the LSE alone group, a group composed of subjects in both physical training groups combined who attended training sessions ≥ 2 d/wk showed favorable changes in cardiovascular fitness (P < 0.001), %BF (P = 0.001), and VAT (P = 0.029). We found no evidence that the high-intensity physical training was more effective than the moderate-intensity physical training in enhancing body composition. Conclusions: The cardiovascular fitness of obese adolescents was significantly improved by physical training, especially highintensity physical training. The physical training also reduced both visceral and total-body adiposity, but there was no clear effect of the intensity of physical training. 2002;75:818-26. Am J Clin Nutr

Objective: The goal of this study was to evaluate the impact of a 10-month after-school physical activity (PA) program on body composition and cardiovascular (CV) fitness in young black girls. Research Methods and Procedures: Subjects were 8-to 12-year-olds recruited from elementary schools. Body composition was measured using anthropometrics {waist circumference and BMI, DXA [percentage body fat (%BF)] and bone mineral density (BMD)}, and magnetic resonance imaging [visceral adipose tissue (VAT)]. CV fitness was measured using a graded treadmill test. The intervention consisted of 30 minutes homework/healthy snack time and 80 minutes PA (i.e., 25 minutes skills instruction, 35 minutes aerobic PA, and 20 minutes strengthening/stretching). Analyses were adjusted for age, baseline value of the dependent variable, and sexual maturation (pediatrician observation). Results: Mean attendance was 54%. Compared with the control group, the intervention group had a relative decrease in %BF (p Ͻ 0.0001), BMI (p Ͻ 0.01), and VAT (p Ͻ 0.01) and a relative increase in BMD (p Ͻ 0.0001) and CV fitness (p Ͻ 0.05). Higher attendance was associated with greater increases in BMD (p Ͻ 0.05) and greater decreases in %BF (p Ͻ 0.01) and BMI (p Ͻ 0.05). Higher heart rate during PA was associated with greater increases in BMD (p Ͻ 0.05) and greater decreases in %BF (p Ͻ 0.005). Discussion: An after-school PA program can lead to beneficial changes in body composition and CV fitness in young black girls. It is noteworthy that the control and intervention groups differed in change in VAT but not waist circumference. This suggests that changes in central adiposity can occur in response to PA, even in young children, but that waist circumference may not be a good indicator of central adiposity.

PT, especially high-intensity PT, had a favorable effect on several IRS markers in obese adolescents.