Objective The present study examined the effects of post-activation performance enhancement (PAPE) induced by different velocity loss (VL) thresholds on lower-limb explosive performance in sprinters under velocity-based resistance training (VBT). A secondary aim was to identify the optimal VL thresholds (5% and 15%) and recovery time points (PRE, 4, 8, 12, and 16 min) for maximizing PAPE responses. Methods Using a randomized crossover design, fifteen male sprinters completed two PAPE protocols consisting of deep squats performed at 85% 1RM with two VL thresholds (5% and 15%). Countermovement jump (CMJ) performance (jump height, relative power, and vertical impulse) and 30 m sprint performance (total time used and average speed) were assessed at each time point. The total number of squat repetitions completed under each VL condition was also recorded. Results In the 5% VL condition, significant improvements were observed in CMJ jump height ( P = 0.01), relative power ( P = 0.009), vertical impulse ( P = 0.016) at 8 min post-intervention. In addition, both total sprint time and mean speed showed significant changes at 4 min ( P = 0.014; P = 0.030) and 8 min ( P = 0.011; P = 0.006). In contrast, no significant changes in CMJ variables were found at any time point in the 15% VL condition. However, total sprint time and mean speed were significantly improved at 8 min post-intervention ( P = 0.002; P = 0.004). The total number of squat repetitions was significantly lower in the 5% VL condition compared with the 15% VL condition ( P = 0.003 vs. P = 0.042). Conclusion Under two sets of deep squats at 85% 1RM, 5% VL was associated with CMJ improvement at 8 min and 30 m sprint improvement at 4 and 8 min with fewer repetitions, whereas 15% VL improved sprint performance mainly at 8 min with no clear CMJ enhancement.
Wang et al. (Wed,) studied this question.