## 3 Results
### Baseline-Dependent Effect of Vibrotactile Stimulation  
In terms of the mean value, although the CoM movements in the progression and lateral directions were analyzed by performing the curve regression analysis and the linear regression analysis, the results of the curve regression analysis were not statistically significant (\(p=0.898\) and \(0.158\), respectively). Therefore, only the linear regression analysis results are presented in Table 2 and Figure 3. The effect of stimulation on the CV values of the walking speed, stance time, and CoM movement in the lateral direction depends on the CV values obtained when walking without the stimulation. The negative baseline-dependent effect of these variables indicates that the differences between the CV values decreased linearly as the values of the variable increased. Therefore, the subjects were divided into the steady and unsteady groups for each of these variables, and the subjects in these group were different depending on each variable. A comparison of the results of these groups indicates that the CV values of the walking speed and stance time increased in the steady group as a result of stimulation, as shown in Figure 4a,b, respectively. On the other hand, the CV of the CoM movement in the lateral direction decreased in the unsteady group (Figure 4c). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **Variable** & \multicolumn{2}{c}{**Unstandardized Coefficients (95\% CI)**} & \multicolumn{2}{c}{**Standardized Coefficients**} & \multicolumn{2}{c}{**Adjusted R2**} & \multicolumn{1}{c}{\(P\)-Value**} \\ \hline Mean & Walking speed & & \(-0.10\) (\(-0.36\) to \(0.15\)) & \(-0.27\) & \(0.01\) & \(0.38\) \\  & Stance time & & \(-0.01\) (\(-0.22\) to \(0.18\)) & \(-0.06\) & \(0.08\) & \(0.84\) \\  & CoM & Vertical & \(-0.02\) (\(-0.09\) to \(0.05\)) & \(-0.18\) & \(0.05\) & \(0.56\) \\  & Progression & \(-0.02\) (\(-0.34\) to \(0.29\)) & \(-0.05\) & \(0.08\) & \(0.84\) \\  & & Lateral & \(-0.63\) (\(-1.32\) to \(0.05\)) & \(-0.52\) & \(0.21\) & \(0.06\) \\ CV & Walking speed & & \(-1.23\) (\(-2.08\) to \(-0.39\)) & \(-0.70\) & \(0.44\) & \(0.008\) * \\  & Stance time & & \(-1.44\) (\(-2.37\) to \(0.52\)) & \(-0.71\) & \(0.47\) & \(0.006\) * \\  & CoM & Vertical & \(-0.01\) (\(-0.52\) to \(0.49\)) & \(-0.02\) & \(0.09\) & \(0.95\) \\  & Progression & \(-0.64\) (\(-1.59\) to \(0.30\)) & \(-0.41\) & \(0.09\) & \(0.16\) \\  & Lateral & \(-0.87\) (\(-1.36\) to \(-0.37\)) & \(-0.76\) & \(0.54\) & \(0.003\) * \\ \hline \hline \end{tabular}  
*: \(p<0.05\).  
\end{table} 
Table 2: Linear regression analysis results showing the effects of values obtained without stimulation and changes in values due to stimulation. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **Variable** & \multicolumn{2}{c}{**Without**} & \multicolumn{2}{c}{**With**} & \multicolumn{1}{c}{**MDC**} & \multicolumn{1}{c}{\(P\)**-Value**} \\ \hline Mean & Walking speed (m/s) & & \(1.32\pm 0.15\) & \(1.29\pm 0.14\) & \(0.10\) & \(0.03\)* \\  & Stance time (s) & & \(0.61\pm 0.05\) & \(0.61\pm 0.05\) & \(0.03\) & \(0.38\) \\  & CoM (cm) & Vertical & \(92.66\pm 2.49\) & \(92.65\pm 2.46\) & \(1.06\) & \(0.97\) \\  & & Progression & \(81.22\pm 6.93\) & \(79.42\pm 7.54\) & \(5.69\) & \(0.02\)* \\  & & Lateral & \(1.92\pm 0.67\) & \(1.75\pm 0.73\) & \(2.17\) & \(0.97\) \\ CV (\%) & Walking speed & & \(2.69\pm 1.28\) & \(3.37\pm 1.65\) & & \(0.38\) \\  & Stance time & & \(1.84\pm 0.76\) & \(2.39\pm 1.12\) & & \(0.15\) \\  & CoM & Vertical & \(0.35\pm 0.20\) & \(0.36\pm 0.25\) & & \(0.86\) \\  & Progression & \(2.48\pm 0.95\) & \(2.61\pm 1.40\) & & \(0.75\) \\  & Lateral & \(35.69\pm 13.00\) & \(32.16\pm 9.81\) & & \(0.38\) \\ \hline \hline \end{tabular}  
*: Values: Mean \(\pm\) standard deviation. MDC: Minimal detectable change. *: Statistically significant difference between values with and without stimulation (\(p<0.05\)).  
\end{table} 
Table 1: Comparison of variables obtained with and without stimulation (stim).