Department of Kinesiology, Louisiana State University, Baton Rouge, Louisiana, U.S.A.
J Electromyogr Kinesiol. 1995 Jun;5(2):81-94. doi: 10.1016/1050-6411(94)00005-7.
The purpose of this investigation was to determine, for a planar multijoint throwing skill, if electromyographic (EMG) amplitudes of eccentric and concentric muscle activity for two agonist muscles (i.e. agonists for the concentric phase) changed over the course of practice. Eighteen men threw a weighted ball with their dominant arm at a target while the motion was restrained to a horizontal plane. EMG and kinematic data were collected for selected practice trials. EMG signals of the triceps brachii (lateral head) and posterior deltoid were full-wave rectified and integrated (IEMG) over two portions of the movement: the countermovement and the throw. Performance showed an expected improvement over trial blocks. IEMG activities of both muscles did not change across trial blocks for the countermovement (eccentric phase) or for the throw (concentric phase) even though several kinematic and kinetic descriptors changed significantly (e.g. during the throw, peak elbow angular velocity and mechanical work by the elbow extensor moment increased during practice). Results suggest that EMG amplitudes of assistive or auxiliary muscles may change rather than primary agonists or that limitations inherent in skill acquisition research and EMG signal processing may be the reasons why no changes were observed in EMG amplitudes.
本研究旨在确定在平面多关节投掷技能中，两个主动肌（即向心阶段的主动肌）的离心和向心肌肉活动的肌电图（EMG）幅度是否随练习过程而变化。18 名男性用优势臂投掷一个加重球，运动限制在一个水平面上。在选定的练习试验中收集肌电图和运动学数据。肱三头肌（外侧头）和后三角肌的肌电图信号在运动的两个部分（反向运动和投掷）进行全波整流和积分（IEMG）。表现随着试验块的增加而提高。尽管几个运动学和动力学描述符（例如，在投掷过程中，肘部角速度峰值和肘部伸展肌力矩的机械功在练习过程中增加）发生了显著变化，但两个肌肉的 IEMG 活动在反向运动（离心阶段）或投掷（向心阶段）期间并没有随试验块而变化。结果表明，辅助或辅助肌肉的 EMG 幅度可能会发生变化，而不是主要的主动肌，或者技能获取研究和 EMG 信号处理固有的限制可能是为什么没有观察到 EMG 幅度变化的原因。
