## 4 Discussion
### Yo-Yo Intermittent Recovery/Max VO\({}_{2}\)  
When examining the effects of different pyometric training protocols on boxers' endurance and cardiopulmonary performance, the results indicate that both the Plyometric Stair Jump (PSJ) and Plyometric Reaction Box Jump (PRJ) training groups showed significant improvements in endurance distance (m) and max VO\({}_{2}\) (mL/kg/min) values after an 8-week training period. These findings highlight that plyometric training impacts strength, explosive power, cardiovascular capacity, and endurance. The endurance distance (m) data revealed significant improvements in the PSJ and PRJ training groups. The results demonstrate that both the Plyometric Stair Jump (PSJ) and Plyometric Reaction Box Jump (PRJ) groups experienced significant improvements in endurance distance and maximal oxygen uptake (max VO\({}_{2}\)) following the 8-week intervention, underscoring the effectiveness of plyometric training in enhancing endurance and cardiopulmonary function. These findings align with previous research indicating that plyometric exercises improve aerobic capacity by enhancing muscle oxygen utilization and increasing the oxygen transport capacity of muscles [53; 67; 68]). The observed increase in max VO\({}_{2}\) further reflects beneficial cardiopulmonary adaptations, including improved oxygen delivery and energy metabolism efficiency [69; 70; 71; 72].  
Although plyometric training is traditionally associated with improvements in anaerobic power and explosive strength, the current findings highlight its broader impact on aerobic endurance performance. This dual effect is particularly valuable in sports such as boxing, where athletes must sustain high-intensity efforts over extended periods while maintaining explosive power. Plyometric training enhances both aerobic and anaerobic energy systems, improving oxygen delivery to muscles and optimizing energy production pathways. Consequently, it offers a comprehensive training approach to improve both strength and endurance capacities, which are critical for competitive success in explosive sports.  
Furthermore, the physiological benefits of plyometric training extend beyond boxing and are applicable to a variety of sports that require a combination of strength, power, and endurance. Plyometric exercises have been shown to enhance aerobic and anaerobic energy systems, improve oxygen delivery to muscles, and optimize overall energy metabolism. Consequently, these adaptations can contribute to improved performance in explosive and endurance-based sports such as basketball, soccer, and track and field events. Expanding the discussion to include these broader sporting contexts highlights the versatility and practical relevance of plyometric training across different athletic disciplines [73].  
In summary, the findings from this study suggest that plyometric training can significantly improve both endurance and cardiopulmonary performance in athletes. Specifically, plyometric exercises increased the endurance distance and max VO\({}_{2}\) values, indicating improvements in aerobic capacity and energy metabolism. While the effects of plyometric training on strength and explosive power are well-documented, this study highlights that it also positively impacts endurance, making it an effective method for enhancing overall athletic performance, especially in sports that require both explosive power and sustained endurance, like boxing. However, it is essential to note that training frequency, duration, and protocol variations could yield different results. As such, careful consideration of training parameters is critical for optimizing the benefits of plyometric training for endurance and cardiopulmonary performance.