## 3 Results  
### Analysis of Hip, Knee, and Ankle Range of Motion  
The ROM of the lower limb joints is shown in Figure 3. No significant effects were found in hip flexion-extension ROM or adduction-abduction ROM across groups or leg preferences. Internal-external rotation ROM showed a significant main effect of group with a large effect size (F (3,123) = 11.505, \(p\) < 0.001, \(\eta^{2}\) = 0.219). Post-hoc analysis revealed that for the preferred leg kicks, MalePro exhibited significantly lower rotation ROM compared to EliteU19 (\(p\) = 0.022). For the non-preferred leg kicks, MalePro had the lowest ROM among all groups, while no significant differences were observed among the other three groups (all \(p\) < 0.05).  
Knee flexion-extension ROM was significantly influenced by leg preference (H = 15.900, \(p\) < 0.001, \(\eta^{2}\) = 0.105), with a medium effect size. Post-hoc analysis showed that among professional players, the preferred leg exhibited a significantly greater knee flexion-extension ROM compared to the non-preferred leg (all \(p\) < 0.01).  
Ankle plantarflexion-dorsiflexion ROM showed no significant differences across groups or leg preferences in the two-way ANOVA.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{1}{c}{**Kicking Performance**} & \multicolumn{2}{c}{**Ball Velocity**} & \multicolumn{2}{c}{**Ball Spin**} \\ \hline \multicolumn{1}{c}{VIF Range} & \multicolumn{3}{c}{1.25-3.69} \\ \multicolumn{1}{c}{R\({}^{2}\)m} & \multicolumn{2}{c}{0.261} & \multicolumn{2}{c}{0.243} \\ \multicolumn{1}{c}{R\({}^{2}\)c} & \multicolumn{2}{c}{0.725} & \multicolumn{2}{c}{0.413} \\ \multicolumn{1}{c}{Predictors} & Estimate (\(\beta\)) & 95\% CI & Estimate (\(\beta\)) & 95\% CI \\ \hline \multicolumn{1}{c}{Hip Add-Abd ROM} & \(-\)0.007 & \([-0.062,0.0047]\) & 0.000 & \([-0.315,0.316]\) \\ \multicolumn{1}{c}{Hip Flex-Ext ROM} & \(-\)0.046 & \([-0.084,-0.007]\) & 0.129 & \([-0.088,0.346]\) \\ \multicolumn{1}{c}{Hip IR-ER ROM} & 0.047 & \([-0.019,0.114]\) & 0.142 & \([-0.227,0.512]\) \\ \multicolumn{1}{c}{Peak Hip Add Vel} & 0.130 & \([-0.116,0.376]\) & \(-0.590\) & \([-2.053,0.873]\) \\ \multicolumn{1}{c}{Peak Hip Abd Vel} & 0.036 & \([-0.239,0.311]\) & \(-1.112\) & \([-2.849,0.625]\) \\ \multicolumn{1}{c}{Peak Hip Hip Flex Vel} & 0.092 & \([-0.102,0.285]\) & \(-0.237\) & \([-1.468,0.994]\) \\ \multicolumn{1}{c}{Peak Hip Ext Vel} & 0.046 & \([-0.145,0.238]\) & \(-0.027\) & \([-1.276,1.223]\) \\ \multicolumn{1}{c}{Fixed Effects} & Peak Hip IR Vel & \(-0.002\) & \([-0.106,0.102]\) & \(-0.357\) & \([-0.976,0.261]\) \\ \multicolumn{1}{c}{Peak Hip Etv Rel} & \(-0.151\)\({}^{*}\) & \([-0.286,-0.106]\) & 0.581 & \([-0.269,1.430]\) \\ \multicolumn{1}{c}{Knee Flex-Ext ROM} & 0.046 & \([0.020,0.072]\) & \(-0.230\)\({}^{**}\) & \([-0.380,-0.081]\) \\ \multicolumn{1}{c}{Peak Knee Flex Vel} & 0.032 & \([-0.094,0.158]\) & 0.086 & \([-0.612,0.785]\) \\ \multicolumn{1}{c}{Peak Knee Ket Vel} & \(-0.089\) & \([-0.261,0.088]\) & 1.640\({}^{**}\) & \([0.686,2.593]\) \\ \multicolumn{1}{c}{Ankle PF-DF ROM} & 0.017 & \([-0.008,0.043]\) & \(-0.099\) & \([-0.245,0.048]\) \\ \multicolumn{1}{c}{Peak Ankle DF Vel} & 0.050 & \([-0.045,0.145]\) & \(-0.355\) & \([-0.884,0.175]\) \\ \multicolumn{1}{c}{Peak Ankle PF Vel} & \(-0.012\) & \([-0.085,0.061]\) & 0.341 & \([-0.080,0.762]\) \\ \multicolumn{1}{c}{Random Effect} & Player Var & 2.326 & 24.645 & \\ \hline \hline \end{tabular}  
* Add: adduction; Abd: abduction; Flex: flexion; Ext extension; PF: plantarflexion; DF: dorsiflexion; Vel: velocity, \({}^{*}\): \(p\) < 0.05, **: \(p\) < 0.001, \({}^{**}\): \(p\) < 0.001.  
\end{table}
Table 4: LMM of lower joint parameters and kicking performance for non-preferred leg kicks.  
Figure 3: _Cont._