## 5 Discussion  
This study investigated the effects of different foot progression angles--toe-neutral, toe-in, and toe-out--on the kinematics and kinetics of the ankle, knee, and hip joints during a side-cutting task. Additionally, the study analyzed the impact of the side-cutting maneuver on ACL loading in the knee through finite element modeling. The results indicated significant differences in the kinematic and kinetic properties associated with the various foot progression angles, particularly highlighting that the TO position may increase the risk of lower limb injuries compared to the toe in the TI position. The knee joint's loading is predominantly influenced by ground reaction forces during different side-cutting techniques. The combination of smaller knee flexion angles and larger internal rotation and abduction angles at initial touchdown results in increased knee loading. Specifically, when the knee flexion angle is minimized, the ground reaction force induces quadriceps muscle contraction, leading to the anterior displacement of the femur relative to the tibia and an increased ACL load [53]. Previous research has demonstrated that an increase in the ankle plantar flexion angle correlates with decreased impact loads on the knee, both anteriorly and vertically. As the plantar flexion angle increases, the foot's contact area with the ground expands, allowing for greater impact energy absorption  
Figure 10: Visualization of von Mises stress distribution for three different lateral cutting tasks (from left to right: toe-neutral, toe-medial, and toe-out). (**A**) Results of Medial collateral ligament stress. (**B**) Results of lateral collateral ligament stress. (**C**) Results of medial tibial cartilage stress. (**D**) Results of lateral tibial cartilage stress. and reducing the load on the knee joint [11; 54]. In this study, a gradual increase in the external rotation angle during foot touchdown corresponded with significant increases in the plantar flexion angle of the ankle joint, suggesting that different foot progression angles exert varying effects on the musculoskeletal system. Notably, the external toe-out position resulted in smaller plantar flexion angles than the internal toe-in position, potentially subjecting the ligaments and muscles around the knee joint to greater impacts and injury risk. Statistical parametric mapping (SPM) analyses revealed significant differences in ankle joint moments at different foot progression angles, with greater moments observed in the TO condition compared to the TI condition. This finding suggests an additional burden on the knee and hip joints, which may compromise joint stability. Changes in muscle activation patterns are equally important; in the present study, foot internal rotation landing EMG activated the H:Q ratio compared to the external toe-out position. Previous studies have reported that an increase in the H:Q ratio indicates a change in muscle activation patterns, which would be accompanied by a decreased risk of non-contact ACL injury [17; 55; 56]. Lower H:Q ratios have been suggested to be a high-risk factor for ACL injury while performing a side-cutting task [19; 55; 57]. Furthermore, observed alterations in the activation patterns of the semitendinosus and gastrocnemius muscles may impact the joint stability and responsiveness to external forces. The gastrocnemius is a knee flexor muscle that exhibits greater stress on the ACL when activated with other muscles [56; 58]. This is consistent with our findings that the toe-in position leads to reduced gastrocnemius activation compared to the toe-out position, which reduces the risk of ACL injury during side-step cutting. The ACL plays a crucial role in maintaining knee stability [59; 60]. While previous studies have primarily linked the ACL injury risk to knee internal and external rotation moments, more recent research indicates that the knee valgus and internal rotation may not be significant indicators of ACL injury [11; 61]. For instance, [PERSON] et al.