Effects of variable resistance training on lower limb explosive power in athletes: a systematic review and meta-analysis

Objectives This study aims to investigate the effects of variable resistance training (VRT) on athletes’ lower limb explosive power through assessments of jumping, sprinting, and change of direction (COD) performance. Methods A systematic search was conducted across four electronic databases (Web of Science, PubMed, Scopus, ProQuest) from their inception until March 23, 2025. Study eligibility was assessed against the Population, Intervention, Comparison, Outcomes, Study design (PICOS) framework. Following data extraction, the methodological quality of the included studies was assessed using the Cochrane Risk of Bias tool. Data analysis was performed using Stata 15 software, with standardized mean differences (SMD) and 95% confidence intervals calculated as the pooled effect size measure. Results Fifteen articles involving 442 participants were included in the final analysis. The overall meta-analysis demonstrated that VRT was an effective method for enhancing athletes’ jumping performance (SMD = 0.81 cm, p < 0.001), sprint performance (SMD = −1.13 s, p < 0.001), and COD performance (SMD = −1.66 s, p < 0.001). Subgroup analyses indicated significant positive effects of VRT on vertical jump (VJ: SMD = 0.31 cm, p = 0.027), squat jump (SJ: SMD = 0.94 cm, p < 0.001), countermovement jump (CMJ: SMD = 1.01 cm, p < 0.001), 5-m sprint (SMD = −1.18 s, p < 0.001), 10-m sprint (SMD = −1.18 s, p < 0.001), 30-m sprint (SMD = −1.08 s, p = 0.013), T-test (SMD = −2.01 s, p < 0.001), repeated change of direction (RCOD: SMD = −2.01 s, p < 0.001), and Illinois test (SMD = −1.85 s, p < 0.001). Conclusion This systematic review suggests that VRT may serve as an effective training strategy for enhancing lower-limb explosive power in athletes. However, due to significant heterogeneity among the included studies and potential publication bias, the definitive benefits of VRT require further validation through additional high-quality research.