Effects of high-intensity interval training on cardiorespiratory fitness, jump, and sprint performance in male under-20 soccer players: a systematic review.

BACKGROUND AND OBJECTIVES: This systematic review and meta-analysis aimed to examine the effects of high-intensity interval training (HIIT) on cardiorespiratory fitness, jump performance and sprint performance in male under-20 soccer players. MATERIALS AND METHODS: A systematic search was conducted across PubMed, Medline, SportDiscus, CINAHL Complete, Scopus, and Web of Science up to March 2026. The review followed PRISMA guidelines and was prospectively registered in PROSPERO. Eligible studies were randomized controlled trials involving male soccer players younger than 20 years exposed to HIIT interventions. Methodological quality was assessed using the TESTEX scale, risk of bias with RoB 2, and certainty of evidence with GRADE. RESULTS: Eight randomized controlled trials involving 203 participants were included. Interventions lasted 5 to 12 weeks, with two to three sessions per week. Meta-analysis showed that HIIT significantly improved VO2max compared with active comparator/control conditions (Hedges' g = 0.53; 95% CI: 0.16 to 0.90; p = 0.0284), while no significant effect was observed for Yo-Yo test performance (Hedges' g = 0.26; 95% CI: -0.58 to 1.09; p = 0.4911). Narrative synthesis showed inconsistent findings for jump and sprint performance, although some studies reported improvements in 30-m sprint performance. The certainty of evidence was low due to serious risk of bias. CONCLUSIONS: HIIT may improve selected physical performance outcomes, particularly VO2max and longer sprint performance, in male under-20 soccer players. SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=1167616, identifier CRD420251167616.