# Analysis of Different Stop-Jumping Strategies on the Biomechanical Changes in the Lower Limbs
## 4 Discussion  
This study aimed to compare lower limb stop-jumping results of the horizontal landing phase mechanics between SJF and SJR. A further aim was to compare the ability of stop-jumping phases to identify differences in stop-jumping horizontal landing phase mechanics. Our hypotheses were generally consistent with our results. We found that there are significant differences in biomechanical changes between two stop-jumping strategies, and our results indicate that SJF might reduce injuries when performed during a stop-jumping phase. Our findings demonstrate that the larger ankle angle resulted in a significant difference in the horizontal landing phase of the knee joint during the two stop-jumping strategies. [PERSON] proved that changes in the sagittal ankle angle during the landing phase can lead to \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Ground Reaction Force (BW).** & **SJR Mean \(\pm\) SD** & **SJF Mean \(\pm\) SD** & \(p\) Value** \\ \hline Peak VGRF & 1.75 (0.29) & 1.56 (0.18) & 0.009 \({}^{*}\) \\ Peak PGRF & 0.95 (0.15) & 0.83 (0.11) & 0.003 \({}^{*}\) \\ \hline \hline \end{tabular} Note: BW: body weight; SD: standard deviation. \({}^{***}\) means significance with \(p<0.05\).  
\end{table} 
Table 4: Comparison of the peak VGRF and PGRF changes between SJR and SJF during the stop-jumping phase. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Joint Kinetics** & **Peak** & **SJR Mean \(\pm\) SD** & **SJF Mean \(\pm\) SD** & \(p\) Value** \\ \hline \multirow{2}{*}{Ankle Moment (Nm/kg)} & Dorsiflexion & 0.64 (0.2) & 0.03 (0.04) & \textless{}0.001 \({}^{*}\) \\  & Plantarflexion & \(-\)1.66 (0.2) & \(-\)1.65 (0.29) & 0.910 \\ \cline{2-5}  & Extension & 3.08 (0.27) & 2.72 (0.36) & 0.001 \({}^{*}\) \\ \cline{2-5}  & Flexion & \(-\)0.67 (0.33) & \(-\)0.47 (0.34) & 0.015 \({}^{*}\) \\ \cline{2-5}  & Extension & 4.18 (1.23) & 2.76 (0.44) & \textless{}0.001 \({}^{*}\) \\ \cline{2-5}  & Flexion & \(-\)1.7 (0.79) & \(-\)0.99 (0.3) & \textless{}0.001 \({}^{*}\) \\ \cline{2-5}  & Dorsiflexion & 11.26 (2.04) & 8.39 (0.56) & \textless{}0.001 \({}^{*}\) \\ \cline{2-5}  & Plantarflexion & \(-\)3.36 (1.26) & \(-\)4.63 (0.9) & \textless{}0.001 \({}^{*}\) \\ \cline{2-5}  & Extension & 15.27 (2.97) & 16.44 (2.14) & 0.236 \\ \cline{2-5}  & Flexion & \(-\)13.99 (3.97) & \(-\)12.07 (2.38) & 0.061 \\ \cline{2-5}  & Extension & 19.21 (6.25) & 7.09 (2) & \textless{}0.001 \({}^{*}\) \\ \cline{2-5}  & Flexion & \(-\)6.33 (1.83) & \(-\)5.05 (0.95) & 0.019 \({}^{*}\) \\ \hline \hline \end{tabular} Note: Nm/kg: Newton meters per kilogram; \(W\)/kg: watts per kilogram; SD: standard deviation. \({}^{***}\) means significance with \(p<0.05\).  
\end{table} 
Table 3: Comparison of the peak joint kinetics changes on the sagittal plane between SJR and SJF during the stop-jumping phase. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Vertical Joint Force (N/kg)** & **SJR Mean \(\pm\) SD** & **SJF Mean \(\pm\) SD** & \(p\) Value** \\ \hline Peak Ankle Joint Force & 16.04 (1.97) & 14.04 (1.49) & \textless{}0.001 \({}^{*}\) \\ Peak Knee Joint Force & 11.71 (1.45) & 11.18 (1.92) & 0.410 \\ Peak Hip Joint Force & 11.62 (1.22) & 11.55 (1.39) & 0.793 \\ \hline \hline \end{tabular} Note: Nm/kg: Newton meters per kilogram; SD: Standard deviation. \({}^{***}\) means significance with \(p<0.05\).  
\end{table} 
Table 5: Comparison of the peak vertical joint force changes between SJR and SJF during the stop-jumping phase. a change in kinetics and kinematics of knee and hip joints [45]. This finding is consistent with our study. The knee joint in our study showed that SJF had higher knee flexion than SJR during the landing of the horizontal phase. The strategy of SJF increased the plantarflexion of ankle angle for simulating soft landing conditions during the landing of the horizontal phase. A previous study showed that a soft-landing strategy could lead to higher knee flexion, reducing landing impact force [46]. Additionally, actively changing the stiffness of the ankle is equivalent to increasing the range of motion [47].