Introduction: The aim of this study was to investigate the impact of different plyometric jump training (PJT) loading strategies, using either weighted vests (WV) or elastic bands (EB), on the physical and physiological performance of young volleyball players. Methods: Thirty-two male volleyball players participated in the study and were randomly assigned to WV-PJT (n = 8), EB-PJT (n = 8), unloaded PJT (UL-PJT, n = 8), and a control group (CG, n = 8). The players in the WV and EB groups performed PJT with resistance equivalent to 10% of body mass, while the UL group engaged in PJT without any additional loads. Moreover, the players in the CG only performed regular volleyball practice. Countermovement vertical jump (CMVJ), 10-m sprint, T-test change of direction speed (T-CODS), reactive strength index (RSI), 1 repetition maximum of leg press (1RMLP), and Wingate anaerobic power tests were measured before and after the 8-week training period. A two-way repeated measures analysis of variance (ANOVA) (4 [group] x 2 [time]), followed by Bonferroni post hoc testing, was employed to identify any significant differences in pairwise comparisons. Results: All training groups (i.e., WV-PJT, EB-PJT, and UL-PJT) showed significant improvements (p = 0.001) in physical and physiological performance outcomes, with effect sizes ranging from small to large over the training period. Both the WV-PJT and EB-PJT groups exhibited greater adaptive changes (p < 0.05) compared to the UL-PJT group after the intervention. For the 1RMLP, the WV-PJT group demonstrated significantly greater adaptive responses (p = 0.011, standard mean difference [SMD] = 0.51, 95% CI = -0.51-1.48) than the EB-PJT group. Conversely, the EB-PJT group showed greater adaptations in the RSI (p = 0.041, SMD = 0.46, 95% CI = -0.53-1.45), as well as in peak power (p = 0.006, SMD = 0.49, 95% CI = -0.53-1.46) and mean power output (p = 0.017, SMD = 0.33, 95% CI = -0.67-1.30) compared to the WV-PJT group. Conclusion: Loaded PJT is an effective method for producing greater adaptations in volleyball players. Specifically, WV-PJT is more beneficial for strength gains, while EB-PJT is superior for improving RSI and anaerobic power output.
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