Is low-volume high intensity interval training a time-efficient strategy for improving body composition and cardiovascular health in children and adolescents? Evidence from a systematic review and three-level meta-analysis.

Objectives: This meta-analysis assessed the impact of low-volume high-intensity interval training (LV-HIIT) on body composition and cardiovascular health in children and adolescents, while examining potential moderating factors. Methods: A systematic search was conducted in PubMed, Web of Science, the Cochrane Library (CENTRAL), and CNKI from inception to April 2025. A three-level random-effects model was used to estimate the overall effects, and subgroup analyses supplemented with meta-regression were performed to explore potential moderators and sources of heterogeneity. Results: A total of 23 studies (996 participants, including 246 females) were included, with 6 studies on normal-weight and 17 on overweight/obese individuals. Compared with controls, low-volume high-intensity interval training (LV-HIIT) significantly reduced BMI (g = -1.24), fat mass (g = -0.99), body fat (g = -0.89), waistline (g = -0.42), weight (g = -0.34), and SBP (g = -0.37), while improving VO2max (g = 1.35). No significant differences were observed versus MICT. Subgroup and dose-response regressions suggested that weight status, age, intervention duration, training frequency, repetitions, and per-repetition time may alter the observed effects. Descriptive findings indicated comparable effects of LV-HIIT with small-sided games and sprint interval training but greater benefits over moderate-intensity interval training. Conclusion: LV-HIIT can effectively and time-efficiently improve body composition and cardiovascular health in children and adolescents, with overall effects comparable to MICT. Exercise prescriptions should carefully consider weight status, age, and intervention characteristics; however, given the limited number of studies and potential bias, the conclusions should be interpreted with caution. Limited descriptive comparisons indicate that LV-HIIT produces effects similar to SSG and SIT, and may offer greater benefits than MIIT. Systematic Review Registration: https://osf.io/exhjm/.