## 4 Discussion
The similar performance improvements between the CLS and TRD groups suggest that both pyometric set configurations effectively enhance vertical jump performance. However, the slightly higher percentage improvement observed in the CLS group may still be attributed to better recovery mechanisms due to the rest intervals, which allow athletes to maintain higher power outputs during training [69; 70]. The Reactive Strength Index (RSI), which reflects an athlete's ability to produce rapid, explosive movements by calculating the ratio of flight time to ground contact time, also improved significantly in both training groups. The CLS group exhibited an 11.90% improvement, while the TRD group saw a 9.02% improvement. The RSI is essential in football, where players frequently need to react quickly, jump, and sprint with minimal ground contact time [51; 71]. Plyometric training has consistently enhanced RSI by improving the stretch-shortening cycle efficiency, enabling athletes to produce more force in less time [10; 72]. The fact that the CLS group outperformed the TRD group suggests that cluster-set training is effective for developing this neuromuscular efficiency due to controlled fatigue management, which allows athletes to execute higher-quality repetitions [40; 73]. One unique finding of the study was that the athletes perceived the task's difficulty significantly greater in one experimental group than the other. Athletes reported that cluster-set training was less physically demanding than traditional training, as evidenced by the finding that the CLS group had a significantly lower Rate of Perceived Exertion (RPE) than the TRD group. This difference is essential, especially when considering training programs in real life; lower perceived exertion will help improve adherence to training programs and reduce the risk of overtraining. By structuring rest intervals within the training session, cluster-set training likely reduces the cumulative fatigue experienced by athletes, enabling them to train at a high intensity without feeling overwhelmed [74; 75]. The lower RPE scores observed in the CLS group may account for the superior improvements in physiological performance (e.g., maximal strength and endurance), psychological factors (such as motivation and enjoyment), and metabolic responses [76; 77]. Athletes who feel less fatigued during training can maintain better technique and execution, contributing to more significant performance gains. This finding highlights the potential long-term benefits of cluster-set training in sports where consistent, high-quality performance is needed over extended periods. Despite the promising results, this study has limitations that should be considered. Firstly, the relatively small sample size may limit the generalizability of the findings to broader populations of football players. Additionally, the study focused exclusively on physical performance metrics without accounting for psychological or tactical variables that could influence on-field performance. Future research should aim to increase the sample size and diversity of participants, incorporating football players of varying skill levels and positions. It would also be valuable to explore integrating pyometric training with other training methods and examine its effects on tactical and technical skills in real gameplay situations.