Background: This study aimed to determine whether acute dietary nitrate supplementation enhances the post-activation performance enhancement (PAPE) response induced by squats performed with a 5% velocity loss (VL) threshold. Methods: A randomized, double-blind, placebo-controlled, crossover design was employed. 20 male long jumpers completed three experimental conditions: placebo (PLA), 5%VL, and beetroot juice (BRJ) + 5%VL. Approximately 2 h following the ingestion of 100 ml of BRJ containing 9.22 mmol of nitrate or a nitrate-depleted placebo, participants performed a squat conditioning protocol at 85% their one-repetition maximum (1RM), employing a 5%VL threshold. Countermovement jump (CMJ) performance was assessed at baseline and at 4, 8, 12, and 16 min post-intervention. Results: At 4 min post-intervention, all three groups showed significant improvements from baseline in CMJ height, peak power output (PPO), and momentum (P < 0.05), with no significant differences observed between the groups. The total number of squat repetitions performed across two sets was significantly higher in the BRJ + 5%VL group compared to both the 5%VL (P = 0.002) and PLA groups (P = 0.027). Conclusion: Squats performed with a 5% VL threshold effectively elicited a PAPE response in male long jumpers, resulting in improved short-term explosive performance. In contrast, acute BRJ supplementation did not enhance the PAPE response or further improve single-jump performance. However, BRJ supplementation was associated with a greater number of squat repetitions completed at 85%1RM, suggesting a potential benefit for squat repetition tolerance and strength-endurance capacity. These findings indicate that low-volume activation protocols may be useful for acutely enhancing explosive performance, whereas acute dietary nitrate supplementation appears unlikely to augment PAPE but may contribute to improved resistance exercise tolerance.
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