## 2 Materials and Methods
### Cardiorespiratory Parameters  
For this study, a maximal multistage progressive treadmill test was conducted using the Technogym Run Exciting 9000 (Technology, Fairfield, NJ, USA). After positioning the participants, a mask ([PERSON], Kansas City, MO, USA) was securely fitted with elastic straps to prevent air leakage, allowing for direct VO2 max measurement using Cosmed's FitMate Med (Cosmed, Rome, Italy). Following the mask placement, a heart rate monitor (Polar Pro Team System, Kempele, Finland) was positioned around the chest, just below the nipples, and fastened. The monitor was placed on bare skin to ensure accurate and continuous heart rate measurements. Cardiovascular and respiratory data were recorded automatically every 15 s. During the test, the participants walked and ran at varying intensities and inclines, following a standardized stepwise continuous test protocol [47; 48]. The variables were measured as in the previous study [33]. The directly measured variables during the test were maximum heart rate (HRmax), anaerobic threshold speed (V/AT), heart rate at the anaerobic threshold (HR AT), heart rate at the first minute of recovery (HR 1\({}^{\prime}\)), heart rate at the second minute of recovery (HR 2\({}^{\prime}\)), and maximum oxygen uptake (VO2 max). Other cardiorespiratory parameters were calculated based on formulas: theoretical maximum heart rate (THRmax; THRmax = 220 \(-\) years) [49], achieved percentages of the load (%HRmax; %HRmax = HRmax/THRmax \(\times\) 100), running efficiency (VO2 max/v), cardiorespiratory efficiency (VO2 max/HR), cardiovascular efficiency (HR AT/kg), percentage of cardiovascular efficiency (% HR AT/kg), percentage of recovery in the first minute (%Re 1\({}^{\prime}\); %Re 1\({}^{\prime}\) = 100 \(-\) HR 1\({}^{\prime}\)/HRmax \(\times\) 100), and percentage of recovery in the second minute (%Re 2\({}^{\prime}\); %Re 2\({}^{\prime}\) = 100 \(-\) HR 2\({}^{\prime}\)/HRmax \(\times\) 100). For clarity, all variables and their abbreviations are arranged in the order they will be used in the subsequent text (Table 2).  
\begin{table}
\begin{tabular}{c c c} \hline
**No.** & **Variable** & **Abbreviation** \\ \hline
1. & Maximum heart rate (bpm) & HRmax \\
2. & Theoretical maximum heart rate (bpm) & THRmax \\
3. & Anaerobic threshold speed (km/h) & V AT \\
4. & Achieve \% of the load on test (\%) & \%HRmax \\
5. & Heart rate at the anaerobic threshold (bpm) & HR AT \\
6. & Heart rate at the anaerobic threshold percentages (\%) & HR AT\% \\
7. & Cardiovascular efficiency (score) & HR AT/kg \\
8. & Percentage of cardiovascular efficiency (\%) & \%HR AT/kg \\
9. & Maximum oxygen uptake (ml/kg/min) & VO2 max \\
10. & Running efficiency (score) & VO2 max/v \\
11. & Cardiorespiratory efficiency (score) & VO2 max/HR \\
12. & Heart rate at the first minute of recovery (bpm) & HR 1\({}^{\prime}\) \\
13. & Heart rate at the second minute of recovery (bpm) & HR 2\({}^{\prime}\) \\
14. & Percentage of recovery in the first minute (\%) & \%Re 1\({}^{\prime}\) \\
15. & Percentage of recovery in the second minute (\%) & \%Re 2\({}^{\prime}\) \\ \hline
16. & Rest lactate (mmol/L) & RL \\
17. & Lactate at 4 min (mmol/L) & LA 4\({}^{\prime}\) \\
18. & Lactate at 10 min (mmol/L) & LA 10\({}^{\prime}\) \\
19. & Metabolic recovery index (score) & Index LA \\
20. & Metabolic efficiency index (score) & Index ME \\ \hline \end{tabular}
\end{table}
Table 2: Cardiovascular and metabolic variables with their abbreviations.