Soccer Players' Physical Performance After Loaded Plyometric-Jump Training: A Systematic Review

Objective: This systematic review examined the effects of loaded plyometric-jump training (LPJT) on physical performance outcomes in soccer players. Methods: A systematic search of PubMed, Web of Science, Scopus and Embase covered all records from database inception to February 2026, with an additional update performed in March 2026. Eligible studies were randomized controlled trials comparing LPJT with unloaded plyometric-jump training (UPJT) or passive control conditions. Methodological quality was assessed using the PEDro scale, risk of bias using RoB 2, and certainty of evidence using the GRADE approach. Findings were synthesized narratively. Results: Six randomized controlled trials involving 214 soccer players met the inclusion criteria. In general, LPJT showed favorable within-group changes in selected physical performance outcomes, particularly horizontal jump performance and some strength- and power-related variables. However, comparable improvements were also observed after UPJT in several outcomes, including vertical jump performance, linear sprint performance, change-of-direction and agility performance, and soccer-specific outcomes. Five studies raised some concerns, and one study presented a high overall risk of bias. The certainty of evidence ranged from low to very low across outcomes. Conclusions: Current evidence remains highly uncertain and does not allow firm conclusions regarding the superiority of LPJT over UPJT or passive control conditions. LPJT may therefore be considered a possible alternative to UPJT rather than a demonstrably superior approach. LPJT may be associated with favorable changes in selected performance outcomes. However, these findings should be interpreted cautiously because of the small evidence base, limited sample sizes, methodological heterogeneity, residual risk of bias concerns, and low to very low certainty of evidence. Further well-designed randomized controlled trials are needed to clarify whether LPJT provides additional benefits beyond conventional unloaded plyometric training.