## 2 Materials and Methods
### Procedures  
A total of three cardiovascular endurance tests were conducted in this study, the GXT performed by the Bruce protocol, the Young Men's Christian Association (YMCA) step test, and the PACER test. A portion of the maximal GXT was used as a method for the submaximal exercise treadmill tests. This was a research design that seeks maximum efficiency, and the GXT, a standard cardiovascular endurance test, was performed to determine the feasibility of the other tests. To minimize the impact between each test, the GXT, YMCA step test, and the PACER test were conducted on different days randomly. All participants took a break of two days or more after each test to minimize the impact of one test on the other. To minimize errors between each measurement, the participants were instructed to refrain from excessive physical activity, smoking, and alcohol consumption the day before visiting the laboratory, and not drink stimulant-containing beverages during testing.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Subgroup (n)** & **Age (years)** & **Height (cm)** & **Weight (kg)** & **BMI (kg/m\({}^{2}\))** \\ \hline \multirow{8}{*}{Males (287)} & 19–24 (31) & 22.68 \(\pm\) 1.49 & 176.08 \(\pm\) 6.60 & 71.66 \(\pm\) 8.73 & 23.16 \(\pm\) 2.63 \\ \cline{2-6}  & 25–29 (33) & 27.27 \(\pm\) 1.38 & 176.06 \(\pm\) 4.58 & 74.44 \(\pm\) 10.30 & 24.09 \(\pm\) 3.24 \\ \cline{2-6}  & 30–34 (34) & 32.09 \(\pm\) 1.29 & 175.55 \(\pm\) 5.96 & 73.61 \(\pm\) 10.60 & 23.82 \(\pm\) 3.14 \\ \cline{2-6}  & 35–39 (33) & 37.15 \(\pm\) 1.28 & 174.19 \(\pm\) 6.49 & 77.02 \(\pm\) 10.90 & 25.24 \(\pm\) 2.96 \\ \cline{2-6}  & 40–44 (34) & 41.71 \(\pm\) 1.34 & 172.28 \(\pm\) 5.46 & 71.08 \(\pm\) 8.04 & 23.88 \(\pm\) 2.23 \\ \cline{2-6}  & 45–49 (34) & 46.79 \(\pm\) 1.32 & 172.32 \(\pm\) 4.74 & 75.14 \(\pm\) 10.03 & 25.21 \(\pm\) 2.99 \\ \cline{2-6}  & 50–54 (23) & 52.70 \(\pm\) 1.52 & 169.11 \(\pm\) 5.95 & 71.77 \(\pm\) 9.31 & 24.96 \(\pm\) 2.14 \\ \cline{2-6}  & 55–59 (34) & 56.82 \(\pm\) 1.64 & 169.32 \(\pm\) 5.42 & 69.76 \(\pm\) 8.01 & 24.21 \(\pm\) 2.19 \\ \cline{2-6}  & 60–64 (31) & 62.29 \(\pm\) 1.42 & 169.96 \(\pm\) 6.25 & 65.35 \(\pm\) 12.50 & 24.03 \(\pm\) 2.48 \\ \cline{2-6}  & Total (287) & 41.83 \(\pm\) 12.83 & 172.56 \(\pm\) 6.46 & 72.27 \(\pm\) 10.30 & 24.28 \(\pm\) 2.76 \\ \hline \multirow{8}{*}{Females (254)} & 19–24 (29) & 22.14 \(\pm\) 1.58 & 162.69 \(\pm\) 4.81 & 54.65 \(\pm\) 6.93 & 20.86 \(\pm\) 2.62 \\ \cline{2-6}  & 25–29 (26) & 27.46 \(\pm\) 1.36 & 163.42 \(\pm\) 6.02 & 54.41 \(\pm\) 5.81 & 20.38 \(\pm\) 1.81 \\ \cline{2-6}  & 30–34 (26) & 31.77 \(\pm\) 1.28 & 162.34 \(\pm\) 5.36 & 56.64 \(\pm\) 10.70 & 21.35 \(\pm\) 3.15 \\ \cline{2-6}  & 35–39 (36) & 36.81 \(\pm\) 1.45 & 162.35 \(\pm\) 6.24 & 57.31 \(\pm\) 7.39 & 21.81 \(\pm\) 2.44 \\ \cline{2-6}  & 40–44 (31) & 42.10 \(\pm\) 1.38 & 161.04 \(\pm\) 4.51 & 59.97 \(\pm\) 9.40 & 22.97 \(\pm\) 3.24 \\ \cline{2-6}  & 45–49 (26) & 47.04 \(\pm\) 1.46 & 160.79 \(\pm\) 5.15 & 57.42 \(\pm\) 6.04 & 22.00 \(\pm\) 2.23 \\ \cline{2-6}  & 50–54 (32) & 52.66 \(\pm\) 1.58 & 158.10 \(\pm\) 4.21 & 55.51 \(\pm\) 6.30 & 22.19 \(\pm\) 2.16 \\ \cline{2-6}  & 55–59 (27) & 56.89 \(\pm\) 1.31 & 157.73 \(\pm\) 4.85 & 57.57 \(\pm\) 6.17 & 23.04 \(\pm\) 2.31 \\ \cline{2-6}  & 60–64 (21) & 61.62 \(\pm\) 1.32 & 154.43 \(\pm\) 5.56 & 56.86 \(\pm\) 8.17 & 23.81 \(\pm\) 3.11 \\ \cline{2-6}  & Total (254) & 41.54 \(\pm\) 12.48 & 160.50 \(\pm\) 5.77 & 56.75 \(\pm\) 7.64 & 22.01 \(\pm\) 2.73 \\ \hline \multicolumn{2}{c}{Total (541)} & 41.69 \(\pm\) 12.66 & 166.89 \(\pm\) 8.60 & 64.98 \(\pm\) 11.99 & 23.21 \(\pm\) 2.97 \\ \hline \hline \end{tabular} BMI: body mass index. Values are means and standard deviation.  
\end{table}
Table 1: Physical characteristics of the subjects.