Wu Ge, Ren Xiaolin
Department of Rehabilitation and Movement Science, Biomedical Engineering Program, University of Vermont, Burlington, VT 05401, USA.
Clin Biomech (Bristol). 2009 Jun;24(5):415-21. doi: 10.1016/j.clinbiomech.2009.03.001. Epub 2009 Apr 7.
Tai Chi Chuan is becoming a popular exercise for improving balance and preventing falls in the elderly. To date, there is no quantitative study investigating the effect of Tai Chi Chuan movement speed on leg muscle function. This study investigated the effect of Tai Chi Chuan exercise performed at different speed on leg muscle activity characteristics in both young and old Tai Chi Chuan practitioners.
Surface electromyography of six leg muscles and kinematics of lower extremity joints were measured in young and old subjects during Tai Chi Chuan practice at fast, normal, and slow speed, respectively. The magnitude and duration of activation, and durations of isometric, concentric and eccentric actions of each muscle were compared among three speeds and between two groups.
The activation duration of all six leg muscles was significantly longer at slower speed than at faster speed (P<0.039). The durations of isometric, concentric and eccentric actions were either longer at the slower speed or did not change with speed for all six leg muscles. The action of knee extensor was primarily isometric at slower speed (P=0.004), and increased significantly to concentric and eccentric at faster speed (P<0.031). The activation magnitude of posterior leg muscles increased with speed (P<0.009). The old subjects had significantly shorter activation duration and lower activation magnitude in several leg muscles than the young, but similar speed effect as the young.
The activation duration and function of leg muscles, especially the knee extensor muscle, are significantly affected by the speed of the selected Tai Chi Chuan movement. Practicing Tai Chi Chuan at different speed may alter the role of muscular function in movement control.
太极拳正成为一种流行的运动，用于改善老年人的平衡能力和预防跌倒。迄今为止，尚无定量研究调查太极拳运动速度对腿部肌肉功能的影响。本研究调查了不同速度的太极拳练习对年轻和老年太极拳练习者腿部肌肉活动特征的影响。
分别在年轻和老年受试者以快、正常和慢速度进行太极拳练习时，测量六条腿部肌肉的表面肌电图和下肢关节的运动学数据。比较三种速度之间以及两组之间每条肌肉的激活幅度和持续时间，以及等长、向心和离心动作的持续时间。
六条腿部肌肉的激活持续时间在较慢速度下均显著长于较快速度（P<0.039）。六条腿部肌肉的等长、向心和离心动作持续时间在较慢速度下要么更长，要么不随速度变化。膝关节伸肌的动作在较慢速度下主要是等长的（P=0.004），在较快速度下显著增加为向心和离心动作（P<0.031）。小腿后部肌肉的激活幅度随速度增加（P<0.009）。老年受试者在几条腿部肌肉中的激活持续时间显著短于年轻人，激活幅度也低于年轻人，但与年轻人有相似的速度效应。
所选太极拳动作的速度显著影响腿部肌肉的激活持续时间和功能，尤其是膝关节伸肌。以不同速度练习太极拳可能会改变肌肉功能在运动控制中的作用。
