## 4 Discussion
### Straight Punch Performance  
The straight punch is defined as a rear-hand punch delivered with the arm furthest from the opponent [38]. It is considered a \"power\" punch that can cause great damage to the opponent [41]. It has been reported that the straight punch can generate greater acceleration of the fist and forearm compared to the jab punch mainly due to the additional rotation of the trunk during its execution [37]. The literature has also reported a higher GRF in the straight punch (1709.28 \(\pm\) 486.62 N) compared to the jab punch (1176.55 \(\pm\) 248.69 N) in amateur boxers. Likewise, a higher peak force has been reported in the straight punch (2328.547 N) compared to the jab punch (1534.514 N) [28]. Similar to the results of this study, where the peak force of the straight punch was also greater, averaging 1664 \(\pm\) 346 N and 1702 \(\pm\) 323 for the test-retest vs. 1019 \(\pm\) 187 N and 1035 \(\pm\) 174 N for the peak force of the jab punch. The group analysis reported significant post-intervention improvements for peak straight punch force (\(\Delta\) 10.5%) in the AEL group. [PERSON] et al. [42] and [PERSON] et al. [43] have mentioned that during the straight punch, the impulse developed in both the vertical and horizontal directions from the rear leg towards the lead leg (produced through plantar flexion of the ankle joint and extension of the knee joint) is crucial for upper limb velocity by improving proximal to distal sequencing during the punch. Therefore, the execution of AEL jumps by increasing the propulsive impulse of the lower body may have led to the improvements in peak straight punch force. Furthermore, it has been suggested that the boxers' ability to maintain a rigid lead leg (by producing vertical anteroposterior braking forces), the generation of lower extremity extensor moments, and the ability to control the degree of knee flexion in the lead leg may enhance force transmission from the lower extremities to the arm/hand segments during the execution of the straight punch [41; 42; 43]. In this regard, it has been suggested that to improve straight punch performance, exercises that increase the ability of the lead leg to absorb force and resist excessive knee flexion and exercises that increase the ability of the rear leg to powerfully extend the hip, knee, and ankle joints are needed [43]. Therefore, the implementation of AEL jumps through acute eccentric loading may help absorb forces at an intermediate degree of knee flexion to subsequently generate force against the ground by extending the lower extremities during the flight phase. Based on the findings of this study, this may be positive for increasing peak straight punch force. The analysis of Rs and NRs indicated that five boxers in the AEL group did not exceed the technical error threshold for straight punch force, and although the delta of these boxers was positive (\(\Delta\) 0-11%), it was not enough to overcome the technical error. As mentioned above, lower relative lower body muscle strength can affect adaptations to AEL training, so athletes with less experience in strength training may see their improvements through AEL diminished by requiring slower-tempo strategiesduring the application of eccentric loads affecting the speed of the eccentric phase and muscle elongation, decreasing the recruitment of motor units and fast-twitch explosive fibers [3,44]. Regarding the CMJ group, there was only one responding boxer (\(\Delta\) 15%), which suggests that a greater stimulus is necessary, through an increase in the volume or intensity of the jumps to improve the peak force of the straight punch in amateur boxers.