<![CDATA[Background & objective: Lower-limb explosive power is an important physical capacity underlying horizontal jumping performance in youth. However, the observed association may be influenced by biological maturation, anthropometry, training status, and overlap between exposure and outcome measurements. This systematic review synthesized evidence on the association between lower-limb explosive power and long-jump performance in youth and examined biological maturation, sex, age, training status, and measurement methods as factors affecting interpretation. Materials for analysis: A systematic search was conducted across PubMed/MEDLINE, Scopus, Web of Science Core Collection, SPORTDiscus, Cochrane CENTRAL, and supplementary sources. The review followed PRISMA 2020 and SWiM principles. Eligible evidence included studies involving participants younger than 18 years that assessed lower-limb explosive power and standing, broad, or running long-jump performance. Evidence was classified according to directness and measurement overlap, and effect estimates were retained in their original statistical forms. Results: Of 1,441 identified records, 517 duplicates were removed and 924 records underwent screening. Following full-text assessment, 21 reports were retained, comprising five primary empirical studies and 16 secondary contextual reports. Only two primary studies directly addressed the review question. Both reported positive associations: one found a moderate bivariate correlation (r = 0.58), while another reported a multivariable correlation (R = 0.687, p = 0.001). Biological maturation emerged as an important developmental factor, while measurement overlap was identified as a major methodological concern. Conclusions: Lower-limb explosive power is positively associated with long-jump performance in youth, but current evidence is insufficient to establish its independent contribution. Future studies should use independent power measures, standardized long-jump outcomes, validated maturation indicators, and longitudinal designs.]]>
