Smith Cory M, Housh Terry J, Herda Trent J, Zuniga Jorge M, Ryan Eric D, Camic Clayton L, Bergstrom Haley C, Smith Doug B, Weir Joseph P, Cramer Joel T, Hill Ethan C, Cochrane Kristen C, Jenkins Nathaniel D M, Schmidt Richard J, Johnson Glen O
University of Nebraska - Lincoln, Lincoln, NE, United States.
University of Nebraska - Lincoln, Lincoln, NE, United States.
J Electromyogr Kinesiol. 2015 Aug;25(4):565-70. doi: 10.1016/j.jelekin.2015.04.014. Epub 2015 May 15.
The purposes of the present study were to examine the effects of electrode placements over, proximal, and distal to the innervation zone (IZ) on electromyographic (EMG) amplitude (RMS) and frequency (MPF) responses during: (1) a maximal voluntary isometric contraction (MVIC), and; (2) a sustained, submaximal isometric muscle action. A linear array was used to record EMG signals from the vastus lateralis over the IZ, 30mm proximal, and 30mm distal to the IZ during an MVIC and a sustained isometric muscle action of the leg extensors at 50% MVIC. During the MVIC, lower EMG RMS (p>0.05) and greater EMG MPF (p<0.05) values were recorded over the IZ compared to away from the IZ, however, no differences in slope coefficients for the EMG RMS and MPF versus time relationships over, proximal, and distal to the IZ occurred. Thus, the results of the present study indicated that during an MVIC, EMG RMS and MPF values recorded over the IZ are not comparable to those away from the IZ. However, the rates of fatigue-induced changes in EMG RMS and MPF during sustained, submaximal isometric muscle actions of the leg extensors were the same regardless of the electrode placement locations relative to the IZ.
本研究的目的是检验在以下过程中，电极置于神经支配区（IZ）上方、近端和远端时，对肌电图（EMG）幅度（均方根值，RMS）和频率（平均功率频率，MPF）反应的影响：（1）最大自主等长收缩（MVIC），以及；（2）持续的次最大等长肌肉活动。使用线性阵列在MVIC以及腿部伸肌以50%MVIC进行持续等长肌肉活动期间，记录股外侧肌在IZ上方、IZ近端30mm和IZ远端30mm处的EMG信号。在MVIC期间，与远离IZ处相比，在IZ处记录到的EMG RMS值较低（p>0.05），EMG MPF值较高（p<0.05），然而，在IZ上方、近端和远端，EMG RMS和MPF与时间关系的斜率系数没有差异。因此，本研究结果表明，在MVIC期间，在IZ处记录到的EMG RMS和MPF值与远离IZ处不可比。然而，在腿部伸肌持续的次最大等长肌肉活动期间，无论电极相对于IZ的放置位置如何，EMG RMS和MPF疲劳诱导变化的速率是相同的。
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