Effects of Whole-Body High-Intensity Interval Training on Fitness in Overweight Adults

This study aims to evaluate the effects of a supervised whole-body high-intensity interval training (WB-HIIT) program on physical fitness and health outcomes in adults with overweight and obesity. WB-HIIT is a practical and time-efficient training modality based on body-weight exercises performed at high intensity with short recovery intervals. It may offer an accessible approach for improving health in individuals with excess body weight. Participants aged 18 to 55 years with a body mass index (BMI) between 25 and 35 kg/m² will take part in a supervised 10-week WB-HIIT program, performed in small groups and led by trained exercise professionals. Before and after the intervention, participants will undergo assessments including DXA-based body composition analysis, fasting blood sampling, muscular strength testing, a Chester step test, a maximal graded treadmill exercise test with gas-exchange analysis to determine VO₂peak, and functional evaluations (chair-stand, arm-curl, and 6-minute walk test). Physical activity and dietary intake will also be recorded. The primary objective of the study is to assess whether WB-HIIT improves cardiorespiratory fitness (VO₂peak) in adults with overweight. Secondary objectives include evaluating changes in muscular strength, body composition, metabolic markers, and functional capacity. The results may help determine whether an equipment-free WB-HIIT program can serve as an effective and accessible training approach for improving health and physical fitness in adults with overweight and obesity.