搂膝拗步膝踝关节预激活与共收缩的表面肌电分析

目的 分析长期太极拳练习者进行搂膝拗步和正常行走时下肢膝、踝关节肌群预激活与共收缩的表面肌电（surface electromyography, sEMG）特征，探讨太极预防跌倒的神经肌肉控制策略。方法 采用Vicon运动捕捉系统、Kistler测力板和Noraxon表面肌电图系统同步采集搂膝拗步和正常行走时股直肌、股二头肌、胫骨前肌、外侧腓肠肌的sEMG信号和体位信息。通过股直肌和股二头肌、胫骨前肌和外侧腓肠肌两对肌肉的积分肌电分别计算膝、踝关节预激活和共收缩。结果 与正常行走相比，搂膝拗步在4个阶段的平均用时显著增加；搂膝拗步在4个阶段内时间百分比存在显著性差异；搂膝拗步膝关节共收缩水平和预激活水平降低，踝关节共收缩水平和预激活水平升高。结论 长期的太极拳练习可能使膝关节周围肌肉的激活水平提高，增强肌肉群之间的协同作用，以帮助稳定关节。研究结果为神经肌肉控制障碍疾病的康复评估和训练提供参考。

Surface EMG Analysis on Pre-Activation and Co-Contraction of Knee and Ankle Joint in Brush-Knee Twist-Step

Objective To analyze muscle pre-activation and surface electromyography (sEMG) characteristics of knee and ankle joints of long-term Tai Chi practitioners during brush-knee twist-step and normal walking, and explore the neuromuscular control strategies of Tai Chi to prevent falls. Methods Vicon motion capture system, Kistler force plate, and Noraxon sEMG system were synchronously used to collect the EMG signals of the rectus femoris, biceps femoris, tibialis anterior muscle, lateral head of gastrocnemius and body posture information during brush-knee twist-step and normal walking. The pre-activation and co-contraction of knee and ankle joints were calculated by integrated EMG of the rectus femoris/biceps femoris, tibial anterior/lateral gastrocnemius muscles. Results Compared with normal walking, the average time of brush-knee twist-step in four phases was significantly increased. There was a significant difference in the percentage of time in four phases. The knee joint co-contraction level and pre-activation level decreased, and the ankle joint co-contraction level and pre-activation level increased. Conclusions Long-term Tai Chi exercises may increase the activation level of the muscles around knee joints and enhance the synergy in muscle groups to help stabilize the joint. The results provide references for rehabilitation assessment and training of neuromuscular control disorders.