Cardiovascular risk profile, oxygen uptake, and perceived exertion rate in children with obesity: The interactive effect of exercise intensity and duration

Background: Although physical exercise is a crucial element in the management of childhood obesity, the most effective training intensity and duration remain controversial. The primary purpose of this study was to analyze the interaction effects of exercise intensity and duration on cardiovascular risk profile, maximum oxygen uptake (VO2max), and rating of perceived exertion (RPE) in obese children. Methods: Eighty obese children were allocated evenly to four groups (20 in each group): groups I and II performed 20 -minute and 40-minute constant-load treadmill training, respectively, with the intensity set at running speed, corresponding to 100% of first ventilatory threshold (VT1), and groups III and IV performed 20 -minute and 40-minute training, respectively, with the intensity set at running speed, corresponding to 80% of VT1. Training was conducted every other day for eight consecutive weeks. Blood lipids, VO2max, and RPE were assessed pre- and postintervention. Results: Postintervention, significant between-group differences regarding all outcome measures (P<0.05) were indicated. Total cholesterol level had dropped significantly in group II compared to the other groups (adjusted P<0.05), and low-density lipoprotein and triglycerides had decreased significantly in group II compared to group III (adjusted P=0.003 and 0.007, respectively). VO2max had increased significantly in group II compared to group I (adjusted P=0.008). RPE had decreased significantly in group II in comparison to other groups (adjusted P<0.05). Conclusion: Intensity and duration are essential factors in aerobic-exercise prescription to reduce cardiovascular risk factors, increase oxygen uptake, and improve perceived exertion in obese children.