Acute Effects of Heavy-Load Squat and Light-Load Ballistic Conditioning Activities on Rebound Jump Performance in Collegiate Male Volleyball Players

Purpose Direct comparisons of post-activation performance enhancement (PAPE) from high-load versus low-load, high-velocity conditioning activities (CAs) in short stretch–shortening cycle (SSC) jumping are lacking. High-load CA is often advocated for stronger athletes, yet the optimal CA remains unclear. This study compared the effects of a 90% one-repetition maximum (1RM) back squat (BSQ) and 30% 1RM jump squat (JS) as CAs on rebound jump (RJ) performance. Methods Seventeen male collegiate volleyball players completed both conditions in a randomized crossover design. After a standardized warm-up, baseline RJ (PRE) was measured, and one set of three CA repetitions was performed. Participants completed five RJs at 3, 7, and 10 min post-CA. Jump height, ground contact time, and reactive strength index (RSI) were measured. Linear mixed models (condition × time fixed effects; participant random) with post hoc tests were applied. The time point of maximal individual PAPE (Peak) was extracted per CA, and PRE versus Peak and between-condition differences were tested. Results No condition × time interaction was detected. Jump height showed a time main effect and was significantly higher than PRE at all post-CA time points (3–10 min) in both conditions. Ground contact time increased at 7 min in BSQ, but no interaction was observed. Peak-based analysis showed RSI was higher than PRE in both conditions, with no between-condition differences. Conclusion Both BSQ90% and JS30% can acutely improve RJ jump height; however, no superiority was observed for SSC efficiency. These findings suggest that distinguishing high-load from low-load, high-velocity CAs may be insufficient to guide optimal CA selection.