## 5 Discussion
explored non-contact ACL injuries during single-leg landings, finding that the axial compression forces generated during these landings significantly contribute to such injuries [19; 58]. Moreover, excessive quadriceps strength and inversion torque may lower the compressive force threshold for injury, indirectly facilitating NC-ACLI development [56; 58]. Thus, our findings suggest that decreased knee flexion and increased abduction angles increase the risk of ACL injury during side-cutting exercises. Modifying side-cutting techniques can effectively reduce the ground reaction forces at the initiation of side-cut movements, inhibiting the knee joint abduction and thereby lowering the ACL injury probability. Specifically, adopting a TI position strategy appears beneficial for reducing knee loading and minimizing the ACL injury risk compared to a TO position. [PERSON] et al. similarly reported that increased ankle flexion-extension during landing significantly reduces internal loading forces on the ACL, indicating that a toe-out position strategy may correlate with a higher ACL injury incidence compared to toe-in situations [8; 10; 11; 62; 63]. Finite element analysis allowed us to evaluate the stresses on various components of the knee joint across different foot progression angles (TN, TI, and TO). The results indicated that, in the TN position, the ACL experienced lower stresses, primarily concentrated at the femoral and tibial attachment regions. In contrast, stresses on the ACL significantly increased in the TN and TO conditions, reaching values of 24.036 MPa and 26.043 MPa, respectively, suggesting that progressively rotating the foot outward can lead to heightened loads. Additionally, the stresses observed in the PCL and meniscus exhibited varying trends across different foot progression angles, with the lateral meniscus and lateral tibial cartilage experiencing the highest stresses in the TO condition. The medial collateral ligament and lateral collateral ligament also demonstrated significantly increased stresses in the TI condition, potentially compromising knee stability and increasing the injury risk [18; 64; 65]. Therefore, optimizing side-cutting techniques, particularly by controlling foot progression angles, can effectively mitigate stresses on knee joint components, thereby reducing the likelihood of sports-related injuries [9; 11; 16; 66; 67]. This study investigated the effects of different foot progression angles (inside toe, outside toe, and neutral) on ankle, knee, and hip kinematics and dynamics during a side-cutting task, revealing the importance of foot position in loading the knee joint during exercise, particularly on the risk of ACL injury. The results of the study show that landing on the outside toe increases the risk of lower extremity injuries, a finding that provides important guidance for training and technique improvement in athletes. First, the study emphasized the dominant role of knee loading by ground reaction forces, noting that small knee flexion angles combined with larger internal rotation and abduction angles increase knee loading, thereby increasing the risk of ACL injury. This finding suggests that coaches and athletes should pay attention to the optimization of side-cutting technique during training to reduce the chance of injury. Therefore, the promotion of an internal toe position strategy may be effective in reducing ACL loading and provide a safer training method for athletes. Finite element analysis further revealed the differences in stress distribution of the ACL and other knee structures under different foot progression angles, and found that the stress in the ACL was lower under toe-in position conditions, while the stress was significantly increased under the external toe-out position conditions, which provided a new understanding of the knee biomechanics, and contributed to the development of more effective training and rehabilitation strategies to minimize the occurrence of sport-related injuries.