## 3 Results  
### Muscle Activities  
The maximum voluntary contractions (MVCs) of the five target muscles obtained from the ten participants are summarized in Table 1. As can be observed from Table 1, the mean and standard error of the target muscles were 105.2 \(\pm\) 15.7 uV, 83.5 \(\pm\) 21.3 uV, 69.2 \(\pm\) 19.8 uV, 47.2 \(\pm\) 9.5 uV, and 159.1 \(\pm\) 55.0 uV for the RF, MG, LG, TA, and PL, respectively. The results showed a fairly high standard error, which could be explained due to the existence of individual differences in muscle-contraction responses among the participants. The statistical analysis showed that the MVCs were statistically different across the target muscles (\(F\) (4,36) = 3.01, \(p\) = 0.03). In addition, the Tukey test revealed significant evidence that the TA and PL muscles showed differences in mean. The averaged %MVCs for the rotated posture (mean \(\pm\) SD; 6.39 \(\pm\) 1.76%) was significantly greater than that (3.86 \(\pm\) 0.68%) for the natural posture (\(F\) (1, 10) = 39.31, \(p\) < 0.001), as shown in Figure 7. In addition, the averaged %MVCs for the rotated posture were more largely increased than the natural posture at high %stroke, and they also showed significance in the statistical test (\(F\) (10, 10) = 3.03, \(p\) = 0.05). It could be observed that the averaged %MVCs for the rotated muscles started to increase at 40% of stroke. Meanwhile, the gaps of the averaged %MVCs between the postures were only 1.9% on average until 70% of stroke, but the gaps then jumped to 4.2% on average, after 70% of stroke. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Participant**} & \multicolumn{5}{c}{**MVC of Target Muscles (Unit: uV)**} \\ \cline{2-6}  & **RF** & **MG** & **LG** & **TA** & **PL** \\ \hline
1 & 69.8 & 36.5 & 16.6 & 7.24 & 105 \\ \hline
2 & 108 & 111 & 167 & 54.5 & 228 \\ \hline
3 & 183 & 65.2 & 116 & 60.9 & 307 \\ \hline
4 & 151 & 236 & 161 & 62.5 & 421 \\ \hline  
The mean %MVC for individual muscle varied by the foot posture and %stroke, as shown in Figure 8. First of all, the mean %MVC for the RF (hip flexion and knee extension muscle) was significantly different depending on the foot posture (\(F\) (1, 10) = 16.35, \(p\) = 0.002) and %stroke (\(F\) (10, 10) = 3.13, \(p\) = 0.043). However, the Tukey test only showed a significant difference between rotated (2.55 \(\pm\) 0.69%) and natural (1.92 \(\pm\) 0.28%) postures, as shown in Figure 8a. The mean %MVC of the gastrocnemius (knee flexion and ankle extension muscles) was significantly changed by the foot posture (\(F\) (1, 10) = 49.38, \(p\) < 0.001) and %stroke (\(F\) (10, 10) = 7.42, \(p\) = 0.002), as shown in Figure 8b. The mean %MVCs for the rotated posture (7.21 \(\pm\) 2.44%) were larger than that for the natural posture (4.33 \(\pm\) 1.35%). Meanwhile, the mean %MVCs of gastrocnemius for both postures increased similarly as %stroke was elevated. The Tukey test showed significant differences of %MVC at 80%, 90%, and 100% of stroke against the initial stroke. The mean %MVC of the PL (ankle extension and aversion muscle) for the rotated posture (4.60 \(\pm\) 1.13%) was significantly larger than that (2.44 \(\pm\) 0.85%) for the natural posture (\(F\) (1, 10) = 19.07, \(p\) = 0.001). However, the mean %MVC of the PL was not significantly changed by the % stroke (\(F\) (10, 10) = 0.48, \(p\) = 0.87). In addition, the gap between the postures narrowed as the %stroke increased, since the mean %MVC for the rotated posture decreased while slightly increasing in the natural posture, as shown in Figure 8c. The mean %MVC of the TA (ankle flexion and inversion muscle) showed an opposite trend as the %stroke increased, as shown in Figure 8d. The rotated posture showed consistent %MVC until 50% of stroke; however, %MVC increased after 50% of stroke. Meanwhile, the natural posture had a decreasing trend until 30% of stroke and resulted in a consistent %MVC after that.