The effects of concurrent training on physical fitness in children and adolescents: a systematic review and meta-analysis

Objective To use a meta-analysis to explore the effects of concurrent training on physical fitness in a population aged (10∼24 years), and to further analyze differences related to factors such as intervention sequence, duration, and frequency. Method The search platform includes data resource systems such as PubMed, Web of Science, Scopus, CNKI, and VIP, with inclusion and exclusion criteria established based on PICOS. Review Manager 5.4 was used for quality assessment and statistical analysis. Results Compared to isolated strength training or endurance training, combined training significantly enhances lower-body explosive power in children and adolescents (MD = 0.05, 95% CI: [0.01, 0.09], I 2 = 0%, P = 0.009) and aerobic capacity (MD = 2.05, 95% CI: [0.80, 3.31], I 2 = 82%, P = 0.001). Subgroup analysis revealed that training strength before endurance within the same period (MD = 2.06, 95% CI: [0.73, 3.39], I 2 = 83%, P = 0.002) and the absence of an interval between the two training sessions (MD = 2.09, 95% CI: [0.50, 3.68], I 2 = 83%, P = 0.01) were associated with greater improvements in VO₂ max in the pediatric and adolescent population. An 8-week concurrent training intervention period resulted in improvements in both maximal oxygen uptake and lower-body explosive power. Conclusion Concurrent training ≤3 times per week does not produce “interference effects” in children and adolescents; concurrent training can significantly improve cardiorespiratory endurance while maintaining strength levels in this population. Systematic Review Registration https://www.crd.york.ac.uk/PROSPERO/view/CRD420251242860 , PROSPERO CRD420251242860.