Delayed lead straight punch performance following resistance priming with different velocity-loss thresholds in highly trained boxers.

Background: Optimizing pre-competition priming is critical for maximizing acute performance in combat sports. Traditional percentage-based training (PBT), which uses a fixed percentage of one-repetition maximum (1RM) for a set number of repetitions, is widely used but lacks autoregulation, potentially causing suboptimal stimulus or excessive fatigue. In contrast, velocity-based training (VBT) adjusts training volume by ending sets when a prescribed velocity loss (VL) threshold is reached, providing individualized fatigue management. This study examined delayed punch-performance responses following traditional PBT and VBT performed with VL thresholds of 10%, 20%, or 30%, with each active condition evaluated relative to a low-intensity active control condition. Methods: Eighteen highly trained male boxers completed five priming conditions in a randomized crossover design, each separated by approximately 5 days: a low-intensity active control condition (CON; bench press at <30% 1RM for 3 sets of 10 repetitions with 3 min rest between sets), percentage-based training (PBT; 3 sets of 5 repetitions at 85% 1RM), and velocity-based training conditions performed at 85% 1RM with sets terminated at 10%, 20%, or 30% velocity loss. In the VBT conditions, barbell velocity was monitored on each repetition, and sets were stopped when mean concentric velocity dropped by the target percentage. Lead straight punch performance was assessed using relative peak punch force (RPF; N/kg), peak punch velocity (PPV; m/s), and an estimated relative punch-power index (RPP; W/kg) at baseline and 6 h, 24 h, and 48 h after priming. Results: The condition × time interactions were not significant for RPF, PPV, or RPP. At baseline, no active condition differed significantly from CON. At 6 h, RPP was significantly higher than CON following PBT, VL10%, and VL20%, whereas PPV was higher than CON following VL10% and VL20%; RPF did not differ significantly from CON. At 24 h, RPP was higher than CON following all active conditions; PPV was higher than CON following PBT, VL10%, and VL20%; and RPF was higher than CON following VL10%, VL20%, and VL30%. At 48 h, no active condition differed significantly from CON. Conclusion: At specific post-intervention time points, VL10% and VL20% showed higher PPV and/or RPP values than the low-intensity active control condition at 6 h and 24 h, whereas VL30% showed higher RPF and RPP values than CON at 24 h. Because the condition × time interactions were not significant and change-from-baseline contrasts were not performed, these findings represent time-specific differences from CON rather than confirmed differences in change from baseline or temporal response. The comparisons also do not establish direct differences among the active protocols, and the unequal training doses across VL conditions preclude identification of an optimal VL threshold.