## 4 Discussion
### The Effect of LT on PAPE  
Different ambient temperatures have varying effects on athletic performance, and by adapting to these temperatures, athletes can achieve optimal training results. We next explored whether LT would have an effect on the induction and maintenance of PAPE. Our results showed that under LT conditions, VJ performance after 4 min, 8 min, and 12 min of 30 cm and 90 cm drop jumps were significantly lower than the pre-test. However, there was no significant difference in VJ performance at 4 min and 8 min after the 60 cm drop jump, while VJ performance at 12 min was significantly lower than the pre-test, indicating that under LT conditions, PAPE was not induced by drop jumps of different heights. In addition, compared with RT conditions, VJ performance after 4 min, 8 min, and 12 min of 30 cm, 60 cm, and 90 cm drop jumps were lower than at RT conditions. This may be due to the fact that muscle movement becomes sluggish with the decrease in temperature when a drop jump is performed at LT conditions [43]. This phenomenon can be explained by the results of [PERSON] et al. [44], who showed a 4.2% decrease in muscle explosive power for every 1 \({}^{\circ}\)C decrease in core temperature. In addition, [PERSON] et al. [45] also showed that muscle temperature decreased at LT conditions, which in turn led to a significant decrease in VJ takeoff time. Furthermore, [PERSON] et al. [46] showed that blood flow to the muscles of the lower limbs was significantly reduced after exercise at LT conditions, leading to a decrease in muscle contractile function and impaired athletic performance. At the same time, LT can lead to a decrease in the maximum contraction force of the muscle, while the force-velocity curve can shift to the left, which in turn reduces the rate of force generation during exercise and affects athletic performance [47]. However, under LT conditions, there was no significant difference in VJ performance at 4 min and 8 min after the 60 cm drop jump compared to the pre-test, while VJ performance at 12 min was significantly lower than the pre-test. Combined with the results that PAPE was effectively induced by a 60 cm drop jump at RT conditions and the PAPE effect was most significant at 4 min and was maintained until 8 min, the effect of PAPE induced by a 60 cm drop jump offset the influence of LT on VJ performance. [PERSON] et al. [48] showed that exercise in LT conditions requires additional muscle effort to maintain athletic performance in order for the body to generate sufficient energy to maintain core temperature and compensate for heat loss, and, therefore, the fatigue produced by exercise results in an offsetting enhancement effect. In addition, many studies have shown that the blood lactate concentration is higher during exercise at LT conditions compared to RT conditions [49; 50], which suggests that the body provides energy for exercise at LT conditions mainly through anaerobic metabolism. However, anaerobic capacity is affected by LT [51], which can affect athletic performance at LT conditions. In addition, LT may affect the ability of the cardiovascular system to deliver oxygen to working muscles and the ability of metabolism to produce sufficient energy [47]. Furthermore, [PERSON] et al. [46] found a significant decrease in muscle temperature in the lower limb after a study on six healthy subjects after prolonged exposure to water below the abdomen at 20 \({}^{\circ}\)C. In summary, LT resulted in a decrease in muscle temperature, with the fatigue effect accounting for the dominant, and the enhancement effect was small. However, PAPE was effectively induced by a 90 cm drop jump at RT conditions, and the PAPE effect was most significant at 8 min, while VJ performance after 4 min, 8 min, and 12 min of 90 cm drop jumps were significantly lower than the pre-test at LT conditions. This may be due to the fact that LT reduces the muscle contractile function.