Falla D, Farina D, Graven-Nielsen T
Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7D-3, DK-9220 Aalborg, Denmark.
J Electromyogr Kinesiol. 2007 Jun;17(3):299-306. doi: 10.1016/j.jelekin.2006.03.005. Epub 2006 Jun 5.
The purpose of this study was to explore changes in spatial muscle activation within the three divisions of the trapezius muscle during a dynamic, cyclic task of the upper limb. Surface EMG signals were detected from thirteen healthy subjects from the upper, middle and lower divisions of the trapezius muscle at multiple electrode sites in the cephalad-caudal direction during a repetitive shoulder flexion task. Initial values and rate of change of average rectified value (ARV) and of instantaneous mean power spectral frequency (iMNF) were estimated at 45 degrees , 90 degrees and 120 degrees of shoulder flexion throughout the 5-min task. The location of the electrodes had a significant effect on initial EMG ARV for both the upper and middle division of the trapezius muscle (P<0.05). Both the rate of change and normalized rate of change of ARV were greatest for the most cranial muscle fibers of the upper division (P<0.05). Initial values and rates of change of iMNF were also affected by electrode location for the upper and lower divisions of the trapezius muscle (P<0.05). These results demonstrate that muscle activity and its changes over time depend on position within the three divisions of the trapezius muscle during a dynamic, cyclic task of the upper limb. This suggests non-uniform muscle fiber distribution and/or recruitment. The results also highlight the importance of multiple recording sites when investigating trapezius muscle function in dynamic tasks.
本研究的目的是探讨在动态循环上肢任务期间斜方肌三个部分内的空间肌肉激活变化。在重复的肩部屈曲任务期间，从13名健康受试者斜方肌的上、中、下部分的多个头端至尾端电极部位检测表面肌电图信号。在整个5分钟任务中，在肩部屈曲45度、90度和120度时估计平均整流值（ARV）和瞬时平均功率谱频率（iMNF）的初始值和变化率。电极位置对斜方肌上、中部的初始肌电图ARV有显著影响（P<0.05）。上部分最头端的肌纤维的ARV变化率和标准化变化率均最大（P<0.05）。电极位置也影响斜方肌上、下部分的iMNF初始值和变化率（P<0.05）。这些结果表明，在动态循环上肢任务期间，肌肉活动及其随时间的变化取决于斜方肌三个部分内的位置。这表明肌肉纤维分布和/或募集不均匀。结果还突出了在动态任务中研究斜方肌功能时多个记录部位的重要性。
