## 4 Discussion  
The aim of this study was to identify the effects of a submaximal accentuated eccentric jump training program on punching performance and CMJ force-time characteristics in amateur boxers. The main findings of this study were the significant group \(\times\) time interaction effects observed for both punching peak force and CMJ performance variables, indicating that the AEL group improved to a greater extent compared to the CMJ and CON  
Figure 6: Individual changes in countermovement jump height, propulsive impulse, peak power, and relative peak power for responders and non-responders across AEL, CMJ, and CON groups. Bars represent \(\Delta\) (delta) values from pre- to post-intervention. Dashed lines indicate the technical error (TE) thresholds used to classify meaningful individual responses. Participant IDs 1–9 correspond to the AEL group, 10–19 to the CMJ group, and 20–29 to the CON group. AEL: accentuated eccentric loading; CMJ: countermovement jump; CON: control; W: watt; kg: kilogram.  
groups. Therefore, the hypothesis raised at the beginning of the research was confirmed. These results are consistent with existing literature reporting improvements in punch strength and power following strength training interventions in amateur boxers [19]. For example, [PERSON] et al. [33] indicated increases in straight punch and curved punch force with the dominant hand in amateur boxers after 16 weeks of training using traditional strength exercises with loads of 50% to 70% of 1 RM, elastic bands of different resistances, and medicine ball exercises. Similarly, [PERSON] [34] reported increases in straight punch power after 12 weeks of training in amateur female boxers through traditional speed-focused strength exercises with intensities of 5 kg to 25 kg. Similarly, [PERSON] et al. [35] observed improvements in straight punch and rear-hand low punch strength along with increases in side punches and lead-hand low punches in amateur boxers after 4 weeks of training using upper and lower body resistance exercises at intensities of 20-90% of 1 RM in combination with glyometric exercises. Based on the current literature, this is the first study to investigate the effects of a submaximal accentuated eccentric loading jump training on punching peak force in amateur boxers.  
Punches require a transmission of force through the boxer's entire kinetic chain, starting with the force applied against the ground by the lower body and then transferring the energy generated through the core to the upper extremities to hit the opponent in the head or trunk [16]. The improvements in the peak force of the punches in the AEL group confirm the importance of the muscle power of the lower body in punches, given that the AEL training program only involved the execution of jumps with 10-20% of the boxers' BM. This is relevant, as current research has suggested that lower body muscle power is strongly associated with punching peak force in elite amateur boxers [16; 36]. Furthermore, amateur boxers who punch harder have been reported to possess higher levels of lower body muscle power compared to boxers who punch with lower impact forces [36]. Early research reporting the importance of leg contribution to punching force highlighted that the lower extremities and trunk contributed 76-78% of the force generated during a punch in experienced boxers [16]. In this regard, boxers in the AEL group may have benefited from the accentuated eccentric loading jump training program by improving force application through triple extension of the ankle, knee, and hip joints, generating greater peak force during punches [25].