## 3 Results
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Variation**} & \multirow{2}{*}{**Time**} & **Mean Difference \(\pm\) SE** & \multirow{2}{*}{**t**} & \multirow{2}{*}{**_p_**} \\  & & **(100 mg-200 mg)** & & \\ \hline \multirow{2}{*}{SBP} & 30 min & \(-0.01097\pm 0.00732\) & \(-1.4985\) & 0.145 \\  & 60 min & \(-0.02008\pm 0.00786\) & \(-2.5530\) & 0.016 \({}^{*}\) \\ \hline \multirow{2}{*}{DBP} & 30 min & \(-0.01852\pm 0.00939\) & \(-1.9720\) & 0.059 \\  & 60 min & \(-0.02498\pm 0.01097\) & \(-2.2760\) & 0.031 \({}^{*}\) \\ \hline \multirow{2}{*}{MaxD} & 30 min & \(0.01953\pm 0.00783\) & 2.495 & 0.019 \({}^{*}\) \\  & 60 min & \(0.00837\pm 0.00638\) & 1.311 & 0.201 \\ \hline \multirow{2}{*}{MinD} & 30 min & \(0.02147\pm 0.00930\) & 2.307 & 0.029 \({}^{*}\) \\  & 60 min & \(0.01718\pm 0.00844\) & 2.035 & 0.052 \\ \hline \multirow{2}{*}{PWV} & 30 min & \(-0.00904\pm 0.04381\) & \(-0.0206\) & 0.838 \\  & 60 min & \(0.05229\pm 0.03464\) & 1.5100 & 0.143 \\ \hline \multirow{2}{*}{PSV} & 30 min & \(-0.03298\pm 0.02186\) & \(-1.509\) & 0.144 \\  & 60 min & \(-0.00489\pm 0.03181\) & \(-0.154\) & 0.879 \\ \hline \multirow{2}{*}{HR} & 30 min & \(0.00818\pm 0.00897\) & 0.912 & 0.373 \\  & 60 min & \(-0.00185\pm 0.01311\) & \(-0.141\) & 0.889 \\ \hline \multirow{2}{*}{SpO\({}_{2}\)} & 30 min & \(-0.002\pm 0.00205\) & \(-0.976\) & 0.338 \\  & 60 min & \(-0.00437\pm 0.00213\) & \(-2.051\) & 0.050 \({}^{*}\) \\ \hline \multirow{2}{*}{Accuracy rate} & 30 min & \(0.01782\pm 0.01168\) & 1.526 & 0.139 \\  & 60 min & \(0.01242\pm 0.01464\) & 0.849 & 0.404 \\ \hline \multirow{2}{*}{Response time} & 30 min & \(-0.01296\pm 0.01064\) & \(-1.218\) & 0.235 \\  & 60 min & \(-0.00403\pm 0.0117\) & \(-0.357\) & 0.724 \\ \hline \hline \end{tabular} Abbreviations: DBP, diastolic blood pressure; HR, heart rate; MaxD, maximum diameter; MinD, minimum diameter; PSV, peak systolic velocity; PWV, pulse wave velocity; \(p\), \(p\)-value; SBP, systolic blood pressure; SE, standard Error; SpO\({}_{2}\), peripheral oxygen saturation; t, t+statistic. \({}^{*}\)\(p<0.05\)  
\end{table} 
Table 7: Comparison of the change rate by caffeine dose using paired \(t\)-test. Figure 8: Comparison of the changes in accuracy rate at each time point (the error bars indicate standard error). \({}^{*}\)_p_\(<\) 0.05. Figure 9: Comparison of the changes in response time at each time point (the error bars indicate standard error). \({}^{*}\)_p_\(<\) 0.05.  
that at 0 min and by 0.27 at 60 min compared to that at 30 min. For a caffeine intake of 200 mg, the VAS was 2.87 \(\pm\) 2.16 at 0 min, 2.83 \(\pm\) 2.09 at 30 min, and 2.57 \(\pm\) 2.05 at 60 min. This value decreased by 0.03 at 30 min compared to that at 0 min and by 0.26 at 60 min compared to that at 30 min. For a caffeine intake of 100 mg, the KSS was 4.87 \(\pm\) 1.59 at 0 min, 4.00 \(\pm\) 1.46 at 30 min, and 4.13 \(\pm\) 1.41 at 60 min. This value decreased by 0.46 at 30 min compared to 0 min and by 0.28 at 60 min compared to 30 min. When the caffeine intake was 200 mg, the KSS was 5.00 \(\pm\) 1.55 at 0 min, 3.87 \(\pm\) 1.22 at 30 min, and 3.87 \(\pm\) 1.28 at 60 min. The 200 mg intake decreased by 1.13 at 30 min compared to that at 0 min and showed no further decrease from 30 min to 60 min (0.00 change). For a caffeine intake of 100 mg, the CFS was 16.30 \(\pm\) 5.53 at 0 min, 14.40 \(\pm\) 5.62 at 30 min, and 16.00 \(\pm\) 5.64 at 60 min. This value decreased by 1.90 at 30 min compared to that at 0 min and increased by 2.10 at 60 min compared to that at 30 min. For a caffeine intake of 200 mg, the CFS was 14.80 \(\pm\) 5.58 at 0 min, 13.20 \(\pm\) 5.64 at 30 min, and 12.80 \(\pm\) 5.31 at 60 min. This value decreased by 1.60 at 30 min compared to that at 0 min and decreased further by 0.40 at 60 min compared to that at 30 min (Table 8). In short, the VAS scores decreased slightly at 60 min compared to those at 0 min for both doses, although this difference was insignificant.