Feasibility and efficacy of adding high-intensity interval training to a multidisciplinary lifestyle intervention in children with obesity – a randomized controlled trial

Abstract Background Multidisciplinary lifestyle interventions for children and adolescents with obesity often include recommendations regarding physical activity, but no structured exercise program. We hypothesized that adding high intensity interval training (HIIT) to a multidisciplinary lifestyle intervention would improve BMI z-score (primary outcome) and health-related quality of life (HRQOL). Methods This randomized controlled trial included 173 children and adolescents with obesity. Participants were allocated to a 12-months lifestyle intervention (N=83) or a 12-month lifestyle intervention accompanied by a 12-week HIIT program at intervention onset (N=90). The HIIT intervention consisted of three weekly sessions and included activities designed to elicit intensities >85% of maximal heart rate. Results Dropout rate was lower in HIIT compared to control at three months (7.8% vs. 20.5%) and 12 months (26.5% vs 48.2%). Changes in Body mass index (BMI) z-score did not differ between HIIT and control at 3 months (Mean Difference (MD): 0.01, 95% confidence interval (CI): -0.09; 0.12, P=0.82) or 12 months (MD: 0.06, CI: -0.07; 0.19, P=0.34). Across randomization (pooled data), BMI z-score was reduced by 0.11 (CI: 0.17; 0.06, P<0.01) at 3 months and 0.20 (CI: 0.26; 0.14, P<0.01) at 12 months. At 3 months, HIIT experienced a greater increase in HRQOL, with increases of 2.73 (CI: 0.01; 5.44, P=0.05) in PedsQL Child total score and 3.85 (CI: 0.96; 6.74, P<0.01) in psychosocial health score compared to control. At 12 months, PedsQL Child physical score was reduced by 6.89 (CI: 10.97; 2.83, P<0.01) in HIIT compared to control. Conclusion Adding a 12-week HIIT program did not further augment the effects of a 12-month lifestyle intervention on BMI z-score, but improved HRQOL after 3 months. Implementation of HIIT in a community-based setting was feasible and showed positive effects on adherence to the lifestyle intervention.