Divergent effects of high-intensity functional training and moderate-intensity continuous training in adolescents with overweight/obesity: a randomized controlled trial on body composition, physical fitness, and psychological health

Objectives: In the wake of the COVID-19 pandemic, declines in physical fitness and psychological resilience among adolescents with overweight/obesity have underscored the need for effective and feasible school-based behavioural interventions. This study compared the effects of High-Intensity Functional Training (HIFT) and Moderate-Intensity Continuous Training (MICT) on body composition, physical fitness, and multidimensional mental health in overweight/obese adolescents. Methods: In this randomized controlled trial, adolescents aged 11-12 years with overweight/obesity were assigned to an 8-week school-based intervention of HIFT, rhythm-/music-accompanied MICT, or a control condition (three sessions per week). Body composition, physical fitness, mood states, and mental health were assessed before and after the intervention. Dietary intake was monitored to ensure stability throughout the study period. Results: Both HIFT and rhythm-based MICT improved body composition, physical fitness, and psychological outcomes compared with the control group. MICT showed stronger effects in reducing overall adiposity and attenuating negative mood and internalizing symptoms such as anxiety and depressive mood. In contrast, HIFT produced greater improvements in cardiorespiratory fitness, muscular fitness and power, and positive mood dimensions including vigor and self-esteem, and showed additional benefits for interpersonal sensitivity. Discussion: Under real-world school conditions, both HIFT and rhythm-based MICT improved body composition, fitness, and mental wellbeing in adolescents with overweight/obesity, but with differential response profiles. These findings support a more tailored ("precision-oriented") selection of school-feasible exercise modalities based on prioritized physical and psychological targets. Clinical Trial Registration: https://www.chictr.org.cn/showproj.html?proj=61446, identifier ChiCTR2100048737.