Meta-analysis of high-intensity interval training and alternative modalities for enhancing aerobic and anaerobic...

This meta-analysis examined whether HIIT outperforms low-intensity endurance training (LIET), generic training (GT), or sport-specific drills (SSD) in improving aerobic and anaerobic endurance in youth athletes. Systematic searches of PubMed, MEDLINE, SPORTDiscus, and Web of Science identified studies comparing HIIT with LIET, GT, or SSD in athletes aged ≤18 years. Outcomes included maximal oxygen uptake (VO₂max), continuous endurance, intermittent endurance, and repeated sprint ability. Random-effects meta-analyses computed standardized mean differences, with risk of bias and sensitivity analyses conducted. Twenty-eight studies (N = 707, 10.7% female) met inclusion criteria. HIIT elicited significantly greater VO₂max improvements than GT (g = 0.97; p < 0.01) and also surpassed GT for continuous endurance performance (g = 0.91; p < 0.01). Compared to LIET, HIIT achieved similar VO₂max and continuous endurance outcomes despite less total training time. Against SSD, HIIT improved continuous endurance performance more (g = 0.41; p = 0.02), while showing no difference in VO₂max, intermittent endurance, or repeated sprint ability. HIIT is an effective, time-efficient modality for enhancing aerobic capacity and continuous endurance performance in youth athletes. It outperforms GT and is at least as effective as LIET and SSD. Coaches should consider incorporating HIIT into youth training programs to optimize endurance adaptations within limited training time. Future research should investigate long-term effects, consider female representation, and evaluate distinct HIIT protocols to further refine evidence-based training guidelines.