## 4 Discussion
### The Effect of Drop Jump Height on PAPE at RT Conditions  
Studies have shown that drop jump training can be effective in improving rapid strength levels, which is important for sports that emphasize explosive power [32; 33]. However, the explosive factor occupies an important place in PAPE. A study by [PERSON] et al. [6] showed that three sets of drop jump training significantly increased the throwing distance of hammer throwers after 1 min, suggesting a significant PAPE effect. Training intensity is the most important factor in inducing PAPE, and different drop jump heights have different effects on PAPE. [PERSON] et al. [34] showed that induced PAPE was most effective in improving athletic performance at 60-84% one-repetition maximum (1 RM) load intensity. A moderate intensity (i.e., 80% 1 RM) may result in significant increases in jumping, repetitive changes in direction velocity, and non-repetitive changes in direction velocity in elite male soccer players compared to low-intensity (60% 1 RM) and high-intensity (100% 1 RM) warm-up protocols [35]. Our results showed that under RT conditions, VJ performance after 4 min and 8 min of 60 cm drop jumps were significantly higher than the pre-test, and the PAPE effect was most significant at 4 min, which was consistent with [PERSON] et al. [36]. In addition, VJ performance after 4 min and 8 min of a 90 cm drop jump was significantly higher than the pre-test, and the PAPE effect was most significant at 8 min, which was in agreement with the findings of [PERSON] et al. [37], where the jumping performance of rugby players was significantly improved 8 min after three sets of an 87% 1 RM back squat. However, there was no significant difference in VJ performance at a 30 cm drop jump after 4 min, 8 min, and 12 min. The effect of recovery time after PAPE induction on subsequent performance needs further study. [PERSON] et al. [38] showed that a significant PAPE window period occurred 3-7 min after load stimulation, i.e., the enhancement effect was greater than the fatigue effect. In addition, a study by [PERSON] et al. [37] on professional football players showed that PAPE appeared at 8 min and 12 min, while the optimal recovery time occurred at 8 min. Furthermore, [PERSON] et al. [39] showed that VJ height and output power increased significantly after resistance training at moderate intensity (70% 1 RM) and high intensity (93% 1 RM), while the PAPE effect was most significant at 4 min. Previous studies have shown that the fatigue effect is believed to dominate immediately after conditioning activities, but the enhancement effect lasts longer. Therefore, a precise schedule is needed for the improvement of athletic performance, and the enhancement effect can be greater than the fatigue effect if the rest interval is long enough. However, the rest interval should not be too long to avoid a decrease in the enhancement effect [17; 40]. In the present study, there was no significant difference in VJ performance at 60 cm and 90 cm drop jumps after 12 min compared to the pre-test. The failure of the PAPE effect to be maintained over 12 min may be due to the enhancement effect being counteracted by the fatigue effect. Many studies have reported the effects of different drop jump heights on training outcomes, and their findings suggest that the optimal drop jump height is not fixed and will exist within a range due to individual differences in athletes [41; 42; 43]. In addition, a previous study has shown that the results are highly individualized for each individual, and there is no consistent training intensity or rest interval that increases the vertical jump height the most for all subjects [36]. Therefore, there will be individualized differences in the duration of maintenance of the PAPE effect due to the different training experience and exercise capacity of the subjects, which is consistent with the findings of [PERSON] et al.