## 4 Discussion
### Associations between Energy Systems and Performance  
This study has illuminated the intricate relationship between energy systems and performance outcomes in the context of repeated sprint tests, examining both the cycling and running modalities. An important finding from the analysis is the notable similarities in how energy systems correlate with performance across these different exercise modalities. The analysis of energy system contributions to performance metrics revealed that, while the specific contributions from the ATP-PCr and glycolytic systems exhibited some variations between cycling and running, the associations between these energy systemsand performance outcomes were broadly consistent across modalities. This suggests a uniform influence of energy system dynamics on performance, regardless of the exercise type. In both the running and cycling tests, the ATP-PCr system showed a significant correlation with peak power outputs, which aligns with previous research suggesting that the immediate energy supply from phosphocreatine breakdown is crucial for high-intensity, short-duration efforts. The glycolytic system, although slightly more variable, still correlated positively with the mean power outputs in both modalities, underscoring its role in sustaining performance over the duration of the sprints. In related research, [PERSON] and [PERSON] (2022) reported the contributions of the ATP-PCr, glycolytic, and oxidative energy systems as 68%, 17%, and 14%, respectively, following a 10 \(\times\) 6 s sprint ([PERSON] and [PERSON], 2022). Contrastingly, in our study, the values were 56%, 31%, and 13% for running, and 53%, 32%, and 15% for cycling. These variances may stem from different sample groups (indoor team sports athletes vs. combat athletes) or the specific RSA test mode employed. Additionally, running and cycling involve distinct forms of muscle contraction. In running, the support phase, where the foot maintains ground contact, constitutes approximately 60% of the stride time at speeds ranging from 12 to 23 km/h. This phase includes around 34% eccentric muscle activation. Such eccentric muscle activity can significantly influence the oxygen consumption during running, as eccentric exercise is known to have a substantially lower metabolic demand compared to equivalent concentric activity ([PERSON] et al., 2019). Furthermore, [PERSON] et al. (2020) identified strong correlations between the results of the Wingate Test against a resistance of 0.09 kg/kg body mass and the contributions of the phospha and glycolytic pathways, as measured by the maximal accumulated oxygen deficit. [PERSON] and [PERSON] (2019), in their study of 12 \(\times\) 20 m running sprints with 20 s recoveries, and [PERSON] et al. (2019), in their examination of 10 \(\times\) 6 s sprints with 30 s of passive rest on a cycle ergometer, both suggested that PCr plays an essential role in ATP resynthesis during RSA. Our study corroborates this, highlighting the crucial role of the ATP-PCr energy system in RSA performance. The results of this study, when juxtaposed with the findings from [PERSON] et al. (2009), provide a comprehensive understanding of the applicability and relevance of different sprint test modalities in assessing anaerobic power and capacity. Our analysis revealed that running-based tests show higher contributions from the ATP-PCr system, which aligns with the higher total energy expenditure and indicates a significant reliance on this energy system for high-intensity efforts, particularly relevant in field sports like soccer. These findings resonate with the significant correlations between the RAST and Wingate test results as noted by [PERSON] et al., which demonstrated the utility of RAST in capturing the anaerobic components crucial to performance across a range of short distances ([PERSON] et al., 2019).