## 4 Discussion
### Acute Effects
Although this may be related to long-term adaptations, the striking-specific isometric exercise may have had an acute effect on the body's ability to stiffen upon impact, thus producing greater stiffness and forces in subsequent strikes. Specific isometric exercise could also have improved the impact force of the punch to a greater extent, due to its greater biomechanical specificity and with perhaps less fatigue compared to dynamic exercise with resistance bands, which could have resulted in a more favorable stimulus towards PAPE [71]. Regarding the improvements through specific exercise with a resistance band in the impact force of the punch, these could be explained by the effect of the resistance bands that generate a greater production and application of force during the entire range of motion, while also according to the authors the punch technique was not altered [59]. However, this study [59] did not control the intensity of the resistance bands, which makes interpretation of its findings difficult. For example, [PERSON] and [PERSON] [84] reported that they used resistance bands at intensities of 78, 108 and 157 newton (N) per 100% elongation, in addition to controlling the training session through the perceived exertion scale (RPE 6-20), determining the type of resistance band and its pre-stretch with an RPE score close to 12, establishing it as the initial resistance to overcome during training, and resulting in a significant improvement in kicking speed by 7% [84]. With everything mentioned thus far, it is important to highlight the recent study by [PERSON] et al. [66], who through the same intervention and sample [59], but measuring the impact force of the punch before, during and after a simulated combat, also reported improvements in the impact force of the punch, although smaller than in their first study [59]. It should be noted that the recovery period after cessation of the potentiating exercise and the striking test before Round 1 of the simulated combat was individualized based on the results of the previous study [59], so that the optimal punch performance was observed between 2 and 13 min after each condition. Analysis of the results suggested a high variability between each subject in relation to the PAPE response. At the individual boxer level, specific isometric exercise was superior in improving neuromuscular performance and punching in six boxers. In contrast, only one boxer improved his punching performance further by performing the resistance band exercise, and only three boxers showed similar levels of performance improvement after both power exercises. As mentioned above, this highlights the large interindividual variability in the PAPE response and confirms the need for coaches to identify the optimal potentiation exercises and recovery period for their boxers, as major changes in performance could be missed by group analyses [66]. The optimal recovery time described in the above studies is within the range proposed by previous reviews of PAPE in various sports [45; 46]. It is clear that in the first minutes after a strengthening exercise there may be few changes or even detriments in performance [45], perhaps due to the presence of fatigue. However, based on the evidence, all of this is highly individualized. Moreover, strength level is also a modulating factor of the PAPE response [46], given that differences in relative strength levels could explain the lower benefit for improving performance in non-responding subjects [46]. In other words, stronger athletes are able to achieve higher levels of PAPE [71; 85], compared to their weaker counterparts. It has been suggested that a higher level of strength may make an individual more resistant to fatigue after a conditioning activity, responding better than weaker athletes [46]. It is important that future research investigates the differences between methods that appear to induce a better PAPE response in the impact force of punches, for example, isometric exercises with punching technique compared to BE and HRE.