## 3 Results
Conversely, the oxidative system exhibits lower \(r^{2}\) values (\(r^{2}\) = 0.31 for running and \(r^{2}\) = 0.29 for cycling), which were not statistically significant (\(p\) = 0.078 and \(p\) = 0.081, respectively). This suggests a less pronounced but still measurable contribution of the oxidative pathway under the conditions of short sprint tests. Such findings indicate that, while the oxidative system is engaged during these sprints, its role may be overshadowed by the more immediate energy contributions from anaerobic sources. The negative coefficients observed for the fatigue index (\(r^{2}\) = \(-\)0.14 and \(r^{2}\) = \(-\)0.11 with \(p\) < 0.05) in both modalities further suggest an inverse relationship between anaerobic energy system contributions and fatigue, implying that a higher anaerobic output might correlate with greater fatigue. Figure 3: The percentage contribution of energy during running and cycling test protocols (sprints only). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Variables**} & **Running** & \multirow{2}{*}{**Cycling Test**} & **Sprint Mode** & \multirow{2}{*}{\(p\)} & \multirow{2}{*}{\(\eta^{2}\)} \\  & **Test** & & **Effect** & & \\ \hline ATP-PCr (\(\%\)) & 55.8 \(\pm\) 4.3 & 52.9 \(\pm\) 2.9 & F = 9.982 & 0.002 & 0.137 \\ Glycolytic (\(\%\)) & 30.8 \(\pm\) 5.0 & 32.7 \(\pm\) 3.6 & F = 2.922 & 0.092 & 0.044 \\ Oxidative (\(\%\)) & 13.4 \(\pm\) 2.4 & 14.5 \(\pm\) 2.6 & F = 3.201 & 0.078 & 0.048 \\ ATP-PCr (k) & 108.9 \(\pm\) 15.7 & 94.7 \(\pm\) 12.2 & F = 15.460 & 0.000 & 0.200 \\ Glycolytic (k) & 61.1 \(\pm\) 8.0 & 58.4 \(\pm\) 8.5 & F = 1.769 & 0.188 & 0.028 \\ Oxidative (k) & 25.9 \(\pm\) 5.5 & 26.0 \(\pm\) 5.8 & F = 0.005 & 0.985 & 0.000 \\ Energy demand & \multirow{2}{*}{9.4 \(\pm\) 1.0} & \multirow{2}{*}{8.6 \(\pm\) 0.9} & F = 9.951 & 0.002 & 0.138 \\ (L of O\({}_{2}\)) & & & & & \\ TEE (kJ) & 195.7 \(\pm\) 21.4 & 179.0 \(\pm\) 20.9 & F = 9.983 & 0.002 & 0.139 \\ PCr\_breaks (kJ) & 51.4 \(\pm\) 6.3 & 45.8 \(\pm\) 6.2 & F = 12.544 & 0.001 & 0.168 \\ PCr\_epocfast (kJ) & 57.5 \(\pm\) 11.9 & 48.8 \(\pm\) 9.2 & F = 10.433 & 0.002 & 0.144 \\ \hline \hline \end{tabular}  
* TEE = total energy expenditure, PCr_breaks = estimated PCr repayment during rest intervals (kJ), PCr_epocfast = estimated PCr repayment during fast phase of EPOC (kJ).  
\end{table} 
Table 3: Estimated relative and absolute energy system contribution during the running and cycling test. Figure 4 represents the correlation coefficients between the cycling and running sprint test performance metrics. Notably, the mean power (MP) exhibits a moderate positive correlation (0.41) across the two modalities, indicating a significant consistency in power output between the cycling and running tests. This consistency suggests that, while the exercise modalities differ, the relative demand and output in terms of MP are comparably measurable. The heatmap also highlights a weaker correlation (0.08) for the fatigue index across modalities, which points to the varying fatigue dynamics between the cycling and running sprints. This discrepancy underscores the necessity of selecting sport-specific tests that align more closely with the actual performance demands and fatigue profiles experienced in competitive settings.