Effects of high-intensity interval training on physical capacities and substrate oxidation rate in obese adolescents

Abstract

Purpose: To investigate the effects of a 3-week weight-management program entailing moderate energy restriction, nutritional education, psychological counseling and three different exercise training (a: low intensity, LI: 40 % V'O₂max; b: high intensity, HI: 70 % V'O₂max; c: high-intensity interval training, HIIT), on body composition, energy expenditure and fat oxidation rate in obese adolescents.

Methods: Thirty obese adolescents (age: 15-17 years, BMI: 37.5 kg m^-2) participated in this study. Before starting (week 0, W0) and at the end of the weight-management program (week 3, W3), body composition was assessed by an impedancemeter; basal metabolic rate (BMR), energy expenditure and substrate oxidation rate were measured during exercise and post-exercise recovery by indirect calorimetry.

Results: At W3, body mass (BM) and fat mass (FM) decreased significantly in all groups, the decreases being significantly greater in the LI than in the HI and HIIT subgroups (BM: -8.4 ± 1.5 vs -6.3 ± 1.9 vs -4.9 ± 1.3 kg and FM: -4.2 ± 1.9 vs -2.8 ± 1.2 vs -2.3 ± 1.4 kg, p < 0.05, respectively). V'O₂peak, expressed in relative values, changed significantly only in the HI and HIIT groups by 0.009 ± 0.005 and 0.007 ± 0.004 L kg FFM^-1 min^-1 (p < 0.05). Furthermore, the HI and HIIT subgroups exhibited a greater absolute rate of fat oxidation between 50 and 70 % V'O₂peak at W3. No significant changes were observed at W3 in BMR, energy expenditure during exercise and post-exercise recovery.

Conclusion: A 3-week weight-management program induced a greater decrease in BM and FM in the LI than in the HI and HIIT subgroups, and greater increase in V'O₂peak and fat oxidation rate in the HI and HIIT than in the LI subgroup.

Keywords: Body composition; Energy metabolism; Exercise intensity; Fat metabolism; Obesity.