## 3 Results
### Between-Direction Comparison  
A repeated measures ANOVA with a Greenhouse-Geisser correction determined that CoAl1 (ST/VM) in the right lower limb differed statistically significantly between the three YBT-LQ directions (F = 3.394, \(p\) = 0.049). However, post hoc analysis with a Bonferroni correction revealed that CoAl1 (ST/VM) was comparable between the anterior and posteromedial (_p_ = 0.116), anterior and posterolateral (_p_ = 0.181), and posteromedial and posterolateral (_p_ = 1.000) directions. A repeated measures ANOVA with a Greenhouse-Geisser correction for the left lower limb did not show statistically significant CoAl1 (ST/VM) differences between the three YBT-LQ directions (F = 2.022, \(p\) = 0.146). A repeated measures ANOVA with a Greenhouse-Geisser correction determined that CoAl2 (ST/VL) in the right lower limb differed statistically significantly between the three YBT-LQ directions (F = 13.442, \(p\) < 0.001). Post hoc analysis with a Bonferroni correction revealed that CoAl2 (ST/VL) for the anterior direction was statistically significantly larger than that for the posteromedial (_p_ < 0.001) and posterolateral (_p_ = 0.001) directions. At the same time, CoAl2 (ST/VL) was comparable between the posteromedial and posterolateral directions (_p_ = 1.000). A repeated measures ANOVA with a Greenhouse-Geisser correction in the left lower limb revealed that CoAl2 (ST/VL) also differed statistically significantly between the three YBT-LQ directions (F = 5.651, \(p\) = 0.009). Like the right lower limb, post hoc analysis with a Bonferroni correction revealed that CoAl2 (ST/VL) for the anterior direction was statistically significantly larger than that for the posterolateral direction (_p_ = 0.024). Although CoAl2 (ST/VL) for the anterior direction was larger than that for the posteromedial direction, the difference was not statistically significant (_p_ = 0.077). Again, CoAl2 (ST/VL) was comparable between the posteromedial and posterolateral directions (_p_ = 1.000). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{5}{c}{**Surface Electromyography-Based CoAls**} \\ \hline \multirow{2}{*}{**CoAl**} & **YBT-LQ Direction** & **Right Limb** & **Left Limb** & **Between-Limb \(p\)-Value** \\ \hline \multirow{4}{*}{CoAl1 (ST/VM)} & Anterior & 54.55 \(\pm\) 29.17 & 56.30 \(\pm\) 46.45 & 0.826 \\ \cline{2-5}  & Posteromedial & 43.44 \(\pm\) 28.08 & 48.69 \(\pm\) 37.25 & 0.318 \\ \cline{2-5}  & Posterolateral & 43.86 \(\pm\) 27.55 & 41.81 \(\pm\) 24.54 & 0.624 \\ \hline \multirow{4}{*}{CoAl2 (ST/VL)} & Anterior & 60.32 \(\pm\) 31.79 & 63.56 \(\pm\) 41.81 & 0.681 \\ \cline{2-5}  & Posteromedial & 40.79 \(\pm\) 20.35 & 46.64 \(\pm\) 27.06 & 0.130 \\ \cline{2-5}  & Posterolateral & 41.24 \(\pm\) 25.49 & 42.39 \(\pm\) 29.86 & 0.839 \\ \hline \multirow{4}{*}{CoAl3 (BF/VM)} & Anterior & 40.82 \(\pm\) 27.52 & 41.47 \(\pm\) 27.15 & 0.906 \\ \cline{2-5}  & Posteromedial & 48.95 \(\pm\) 33.74 & 54.27 \(\pm\) 42.49 & 0.383 \\ \cline{2-5}  & Posterolateral & 53.27 \(\pm\) 27.92 & 50.53 \(\pm\) 35.50 & 0.565 \\ \hline \multirow{4}{*}{CoAl4 (BF/VL)} & Anterior & 44.48 \(\pm\) 27.59 & 47.78 \(\pm\) 31.23 & 0.523 \\ \cline{2-5}  & Posteromedial & 45.88 \(\pm\) 25.75 & 51.87 \(\pm\) 32.67 & 0.280 \\ \cline{1-1} \cline{2-5}  & Posterolateral & 51.43 \(\pm\) 27.65 & 49.30 \(\pm\) 32.22 & 0.708 \\ \hline \end{tabular} Values expressed as arithmetic mean and standard deviation (\(\pm\)). BF, biceps femoris, CoAl, coactivation index; VL, vastus lateralis; YBT-LQ, Lower Quarter Y-Balance Test.  
\end{table} 
Table 5: The between-limb comparison of the four studied CoAls. A repeated measures ANOVA with a Greenhouse-Geisser correction determined that CoAI3 (BF/VM) in the right lower limb differed statistically significantly between the three YBT-LQ directions (F = 4.114, \(p\) = 0.026). Post hoc analysis with a Bonferroni correction revealed that CoAI3 (BF/VM) for the posteromedial direction was statistically significantly larger than that for the anterior direction (\(p\) = 0.034).