This study aimed to compare the post-activation performance enhancement induced by successive drop-jumps performed on hard or sand surfaces in the sprint and jump performance of top-level sprinters. Athletes were tested on 2 occasions. On each visit they were allocated to one of the experimental protocols, which consisted of performing 2×5 drop-jumps from a box height of 60 cm on hard or sand surfaces in a randomized order, 7 days apart. Prior to and 7 and 15 minutes after executing the drop-jumps, the sprinters performed countermovement jumps and 60-m sprint tests. Differences between sprinting splits and surfaces were assessed using a two-way analysis of variance with repeated measures. No significant differences in jump height or sprint time were observed (P> 0.05), regardless of the surface used (i.e., hard or sand) during the conditioning activity (effect sizes [95% confidence intervals] ranging from 0.01 [-0.84; 0.84] to 0.44 [-0.42; 1.27]). Performing drop-jumps on sand or hard surfaces immediately before maximum sprinting bouts does not provide any additional benefit to top-level sprinters. Sprint coaches may prescribe short-plyometric training activities on sand surfaces even close to competitions, bearing in mind that this strategy will not compromise sprint-specific performance.
Fonte: Journal of Human Kinetics, in press, 2021.