Effects of a 12-Week High-Intensity Interval Training Program on Body Fat Percentage and Lean Body Mass in Boys Aged 10–12 Years

Abstract

A 12-week high-intensity interval training (HIIT) program appears to be an effective and practical strategy for improving body composition in boys aged 10–12 years. Based strictly on the results reported in the source study, 20 boys were randomly assigned to either a HIIT group or a control group, and baseline comparisons showed no significant differences between groups in age, height, weight, or body mass index, supporting the comparability of the sample before the intervention. The HIIT program was performed three times per week for 12 weeks, with each session lasting about 40 minutes and including warm-up, repeated exercise bouts with active recovery, and cool-down. After the intervention, the HIIT group showed a statistically significant reduction in body fat percentage compared with the control group (p = 0.029), while lean body mass increased significantly in the HIIT group relative to the control group (p = 0.002). In contrast, the control group did not demonstrate meaningful change, indicating that the observed improvements were associated with the exercise intervention rather than normal variation alone. These findings suggest that HIIT may offer a time-efficient method for promoting healthier body composition during childhood, which is especially important given current public health concerns about low physical activity and increasing childhood obesity. Current World Health Organization guidance recommends that children and adolescents accumulate at least 60 minutes of moderate- to vigorous-intensity physical activity daily, including vigorous activities regularly, and systematic reviews have shown that HIIT can improve health-related fitness and selected cardio metabolic outcomes in children and adolescents, particularly in structured and school-based settings. Overall, the study supports the use of a structured HIIT protocol as a feasible, short-term, and school-compatible approach to reducing body fat and increasing lean body mass in young boys.