## 4 Discussion  
In this study, we analyzed changes in lower limb muscle activity and gait ability according to walking speed in patients post-stroke. Participants conducted 20 m overground walking under three conditions: slow speed, self-selected speed, and maximum speed. The patients who had had a stroke showed a tendency toward increased paretic-side lower limb muscle activity with faster walking speeds. Specifically, in the stance phase, rectus femoris activity significantly increased from 659.95 to 1319.67 %RVC (99.97%). In the swing phase, significant increases were observed in the rectus femoris (407.49 to 849.66, 108.51%), biceps femoris (604.73 to 1118.23, 84.91%), and gastrocnemius (329.56 to 576.36, 74.89%) (_p_ < 0.05 for all). Conversely, gluteus medium activity decreased slightly as walking speed increased, but this change was not statistically significant (_p_ > 0.05). The increase in muscle activity in the paretic lower limb at higher walking speeds possibly reflects greater neuromuscular demand, as faster walking requires additional muscle recruitment. At maximal speed, participants might have increased activation of muscles associated with knee flexion, hip extension, and ankle push-off, potentially generating greater propulsive force. This pattern shows a compensatory strategy to support and move the limb more quickly. However, this is not a novel finding, as previous studies have reported similar results [1,28,29]. One interesting finding of this study was the tendency for gluteus medius muscle activity to decrease as walking speed increased, contrary to the overall pattern observed in other muscles. These results may be associated with the interaction between the functional role of the gluteus medius and the use of walking aids. During the single-limb support \begin{table}
\begin{tabular}{l l l l l l l} \hline \hline \multirow{2}{*}{**Parameters**} & \multicolumn{2}{c}{**Slow Speed**} & \multicolumn{2}{c}{**Self-Selected**} & \multicolumn{2}{c}{**Maximum**} & \multirow{2}{*}{**F(_p_)**} & \multirow{2}{*}{**Post hoc**} \\  & **Walking** & & & & & & \\  & **(A)** & & & & & & \\ \hline \multirow{8}{*}{Paratic side} & STL (\%height) & 46.22 \(\pm\) 13.01 & 53.26 \(\pm\) 12.14 & 60.00 \(\pm\) 12.96 & 44.100 & A \(<\) B, B \(<\) C, \\  & STP (\%cycle) & 57.25 \(\pm\) 4.61 & 57.04 \(\pm\) 5.26 & 57.17 \(\pm\) 5.11 & 0.030 (0.970) & \\  & SWP (\%cycle) & 42.75 \(\pm\) 4.61 & 42.95 \(\pm\) 5.26 & 42.82 \(\pm\) 5.11 & 0.027 (0.973) & \\  & SLST (\%cycle) & 37.14 \(\pm\) 3.72 & 37.44 \(\pm\) 4.83 & 38.05 \(\pm\) 5.19 & 0.645 (0.529) & \\  & STL (\%height) & 45.99 \(\pm\) 13.07 & 53.23 \(\pm\) 12.09 & 59.09 \(\pm\) 13.32 & 41.318 & A \(<\) B, B \(<\) C, \\  & STL (\%height) & 45.99 \(\pm\) 13.07 & 53.23 \(\pm\) 12.09 & 59.09 \(\pm\) 13.32 & (+0.001) & A \(<\) C \\  & STP (\%cycle) & 62.09 \(\pm\) 5.57 & 62.66 \(\pm\) 4.86 & 61.87 \(\pm\) 5.19 & 0.302 (0.741) & \\  & SWP (\%cycle) & 36.97 \(\pm\) 3.77 & 37.33 \(\pm\) 4.86 & 38.12 \(\pm\) 5.19 & 1.011 (0.372) & \\  & SLST (\%cycle) & 42.81 \(\pm\) 4.63 & 43.00 \(\pm\) 5.22 & 42.73 \(\pm\) 5.11 & 0.053 (0.949) & \\  & STL & \(-0.25\pm\) 1.31 & \(-0.02\pm\) 0.51 & \(-0.82\pm\) 4.51 & 0.534 (0.590) & \\  & STP & \(3.98\pm\) 7.33 & 4.72 \(\pm\) 7.47 & 3.94 \(\pm\) 8.23 & 0.173 (0.841) & \\ GAI & SWP & \(-7.15\pm\) 9.15 & \(-6.93\pm\) 11.08 & \(-5.82\pm\) 11.93 & 0.305 (0.738) & \\  & SLST & 6.99 \(\pm\) 9.05 & 6.85 \(\pm\) 11.02 & 5.80 \(\pm\) 11.96 & 0.258 (0.774) & \\ \hline \hline \end{tabular} Note. Values are expressed mean \(\pm\) SD. STL, stride length; STP, stance phase; SWP, swing phase; SLST, single-limb support time; GAI, gait asymmetry index (S) (Non particle side variable \(-\) Pareto side variable)/(Non particle side variable \(+\) Pareto side variable \(\times\) 100. A \(<\) B, B \(<\) C, A \(<\) C: Significant differences between walking speeds (slow and self-selected, self-selected and maximum, and slow and maximum) based on post hoc comparisons (_p_ < 0.05).  
\end{table}