Adding High-Intensity Interval Training to a Multidisciplinary Lifestyle Intervention for Childhood Obesity:...

Children and adolescents with overweight or obesity are less physically active than their lean counterparts. We examined the effects of adding a 3-month high-intensity interval training (HIIT) program to a 12-month lifestyle intervention on physical activity (PA) in children and adolescents with overweight or obesity. Participants were randomized to a 12-month lifestyle intervention (control, N = 83) or a 12-month lifestyle intervention with a 3-month HIIT program (HIIT, N = 90). PA was assessed using accelerometry at baseline, and subsequently at 3 and 12 months. Linear mixed models estimated the mean difference in PA intensity between groups. Associations were explored using Pearson's correlation coefficient. The HIIT group showed a greater increase in moderate-to-vigorous PA (MVPA) after 3 months (p = 0.04), with a mean increase of 8.3 min per day (p < 0.01) compared to 0.9 min per day (p = 0.75) in the control group. At 12 months, there was no difference between the groups (p = 0.64), and MVPA returned to baseline levels. Across randomization, sedentary time increased by 17.5 min per day (p = 0.02) at 3 months and by 29.9 min per day (p < 0.01) at 12 months. Changes from baseline to 12 months in vigorous activity were inversely correlated with changes in BMI z-score (r = -0.26, p = 0.02). Adding a 3-month HIIT program to a 12-month lifestyle intervention in children and adolescents with overweight or obesity increased MVPA at 3 months, but not at 12 months. The inverse correlation between changes in vigorous-intensity PA and changes in BMI z-scores underscores the potential of incorporating vigorous-intensity activities into obesity treatment programs. Trial Registration: ClinicalTrials.gov: NCT05465057.