A174: Obese Adolescents

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Background/Purpose: The incidence of overweight and obesity among adolescents is escalating rapidly. Many studies have validated the efficacy of low-volume, high-intensity interval training (HIIT) in ameliorating cardiometabolic risk factors in individuals with obesity. Nonetheless, the influence of exercise frequency—a pivotal element in HIIT's effectiveness—requires further exploration. This study aimed to evaluate the impacts of different HIIT frequencies on body composition and cardiorespiratory fitness in adolescents aged 10-13 years with obesity. Methods: Sixty adolescents with obesity aged 10-13 (age: 11.0±3.0 years, BMI: 23.4±2.5 kg/m^2) were randomly allocated to three exercise intervention groups (IG1, IG2, and IG3) and a non-exercise control group (CG). The intervention groups engaged in the same running-based HIIT program at varying frequencies: once weekly (IG-1, n=15, 10 males, 5 females), twice weekly (IG-2, n=15, 10 males, 5 females), and thrice weekly (IG-3, n=15, 10 males, 5 females). The CG (n=15, 9 males, 6 females) participated in only regular school physical education and extracurricular activities without additional exercise. Each HIIT session comprised 3 sets of 8 high-intensity 15-second runs at 100% maximal aerobic speed (MAS) and 8 recovery jogs of 15 seconds at 50% MAS, with a 3-minute rest between sets, totaling 18 minutes. Body composition and cardiorespiratory fitness were assessed before and after the intervention. Between-group comparisons were conducted using single-factor ANOVA, and within-group differences were analyzed with paired-samples t-tests. Results: Post a 12-week intervention, all experimental groups exhibited improvements in body composition and cardiopulmonary fitness, notably IG-3 and IG-2, which demonstrated significant enhancements. IG-3 showed significant changes in weight, BMI, body fat percentage, total body fat mass, fat-free mass, VAT, VO2max, systolic blood pressure, and waist circumference (t-values: 8.726, 7.020, 10.960, 4.923, -3.328, 4.948, -10.557, 2.957, 5.113; P < 0.05), as did IG-2 across these metrics (t-values: 8.15, 6.615, 10.831, 5.028, 6.64, -13.705, 2.965, 3.214, 3.453; P < 0.05). Conversely, the CON and IG-1 groups exhibited fewer improvements, with IG-1 showing gains in BMI, FM, BF, FFM, and VO2max (t-values: 3.638, 7.164, 5.551, -3.392, -6.884; P < 0.05). Relative to the control group CG, IG-2 emerged with the most differential indicators post-intervention, followed by IG-3, with IG-1 presenting the least. Conclusion: Running-based high-intensity interval training twice weekly optimally boosts body composition and cardiorespiratory fitness in adolescents with obesity. This frequency balances efficacy and practicality, offering a viable method to combat adolescent obesity. Future research should explore long-term effects and adherence to these exercise regimens.