Effects of obesity and gender on exercise capacity in urban children.

Background: The prevalence of childhood and adolescent obesity has been rising steadily over the last few decades and is now considered one of the most important issues worldwide.

Objective: The goal of this study was to investigate the influence of body mass on fitness in a healthy cohort of urban children and adolescents and to evaluate the difference in the cardiovascular responses, as measured by heart rate and endurance time, elicited with exercise in each gender.

Methods: This observational study was conducted in an exercise laboratory. Participants were healthy boys and girls aged 4 to 18 years. The study evaluated heart rate and endurance time during exercise testing on a treadmill. Outcome measures were endurance time and heart rate.

Results: The study comprised 303 boys and 222 girls ranging in age from 4 to 18 years (mean [SD], 12.2 [3.48] years). Obese children had a significantly lower endurance time than nonobese children (boys, P < 0.0001; girls, P = 0.0001). The mean (SEM) decrease in endurance time for obese versus nonobese children was 1.90 (0.38) minutes for boys and 1.52 (0.39) minutes for girls. A decrease in mean endurance time of 0.69 minute for each unit increase in BMI was noted. Obese boys and girls performed at a higher heart rate than their nonobese counterparts, although there was no statistically significant difference in maximum heart rate achieved by obese and nonobese children (boys, P = 0.71; girls, P = 0.79).

Conclusions: Endurance time was significantly decreased in these obese boys and girls, and they performed at a higher heart rate earlier in exercise than nonobese children. There was no significant difference in maximum heart rate between obese and nonobese children.