Abstract：
BACKGROUND: Most studies on cutting have focused on the biomechanics of the knee and lower-limb muscle activation characteristics, with less consideration given to the influence of motor experience on control strategies at the joint level. This study aimed to investigate the differences in knee stability and inter-joint coordination between high- and low-level athletes when cutting at different angles.
METHODS: A Vicon motion capture system and a Kistler force table were used to obtain kinematic and ground reaction force data during cutting. Joint dynamic stiffness and vector coding were used to assess knee stability and inter-joint coordination. Uncontrolled manifold analysis was used to clarify whether there was synergy among lower-limb joints to maintain postural stability during cutting.
RESULTS: During the load acceptance phase, skilled subjects had the smallest joint stiffness at 90° compared with novice subjects (P < 0.05). Compared with novice subjects, skilled subjects had smaller knee-hip ellipse areas at 90° and 135° (P < 0.05), but larger knee-ankle ellipse areas at 135° (P < 0.05). The synergy index in load acceptance was significantly higher (P < 0.05) for skilled subjects at 90° and 135°.
CONCLUSIONS: Advanced subjects can adjust joint control strategies to adapt to the demands of large-angle cutting on the change of direction. Advanced subjects can reduce knee stability for greater flexibility during cutting compared with novice subjects. By increasing the degree of synergy among the lower-limb joints, advanced athletes can maintain high postural stability.
METHODS: A Vicon motion capture system and a Kistler force table were used to obtain kinematic and ground reaction force data during cutting. Joint dynamic stiffness and vector coding were used to assess knee stability and inter-joint coordination. Uncontrolled manifold analysis was used to clarify whether there was synergy among lower-limb joints to maintain postural stability during cutting.
RESULTS: During the load acceptance phase, skilled subjects had the smallest joint stiffness at 90° compared with novice subjects (P < 0.05). Compared with novice subjects, skilled subjects had smaller knee-hip ellipse areas at 90° and 135° (P < 0.05), but larger knee-ankle ellipse areas at 135° (P < 0.05). The synergy index in load acceptance was significantly higher (P < 0.05) for skilled subjects at 90° and 135°.
CONCLUSIONS: Advanced subjects can adjust joint control strategies to adapt to the demands of large-angle cutting on the change of direction. Advanced subjects can reduce knee stability for greater flexibility during cutting compared with novice subjects. By increasing the degree of synergy among the lower-limb joints, advanced athletes can maintain high postural stability.
摘要：
背景：大多数关于切割的研究都集中在膝盖和下肢肌肉激活特征的生物力学上，较少考虑电机经验对关节级控制策略的影响。本研究旨在探讨高低水平运动员在不同角度切割时膝关节稳定性和关节间协调性的差异。
方法：使用了Vicon运动捕获系统和Kistler力表，以获得切割过程中的运动学和地面反作用力数据。关节动态刚度和矢量编码用于评估膝关节稳定性和关节间协调性。未控制的流形分析用于阐明下肢关节之间是否存在协同作用以保持切割过程中的姿势稳定性。
结果：在负载接受阶段，与新手受试者相比，熟练受试者在90°时的关节刚度最小（P<0.05）。与新手相比，熟练受试者在90°和135°时的膝臀椭圆面积较小（P<0.05），但135°处的膝踝椭圆面积较大(P<0.05)。对于90°和135°的熟练受试者,负荷接受的协同指数显著更高(P<0.05)。
结论：高级受试者可以调整关节控制策略，以适应大角度切削对方向变化的需求。与新手受试者相比，高级受试者可以降低膝盖稳定性，从而在切割过程中具有更大的灵活性。通过增加下肢关节之间的协同作用程度，先进的运动员可以保持高度的姿势稳定性。
方法：使用了Vicon运动捕获系统和Kistler力表，以获得切割过程中的运动学和地面反作用力数据。关节动态刚度和矢量编码用于评估膝关节稳定性和关节间协调性。未控制的流形分析用于阐明下肢关节之间是否存在协同作用以保持切割过程中的姿势稳定性。
结果：在负载接受阶段，与新手受试者相比，熟练受试者在90°时的关节刚度最小（P<0.05）。与新手相比，熟练受试者在90°和135°时的膝臀椭圆面积较小（P<0.05），但135°处的膝踝椭圆面积较大(P<0.05)。对于90°和135°的熟练受试者,负荷接受的协同指数显著更高(P<0.05)。
结论：高级受试者可以调整关节控制策略，以适应大角度切削对方向变化的需求。与新手受试者相比，高级受试者可以降低膝盖稳定性，从而在切割过程中具有更大的灵活性。通过增加下肢关节之间的协同作用程度，先进的运动员可以保持高度的姿势稳定性。
