University of Nantes, Laboratory «Motricité, Interactions, Performance» (EA 4334), F-44000, Nantes, France.
J Electromyogr Kinesiol. 2011 Apr;21(2):229-35. doi: 10.1016/j.jelekin.2010.10.012. Epub 2010 Nov 18.
The present study aimed at determining the electromyographic fatigue threshold (EMG(FT)) from the EMG activity level and the EMG frequency content of the First Dorsal Interosseous. Thirty-seven healthy subjects performed seven isometric index abductions at randomly ordered percentages of maximal voluntary contraction (i.e., 20%, 25%, 30%, 35%, 40%, 50% and 60%). During these bouts, surface EMG was measured using a linear electrodes array (i.e., seven EMG channels) in the First Dorsal Interosseous. For each subject the EMG(FT) was determined from both Root Mean Square (RMS) and Mean Power Frequency (MPF) values, only if the following criteria were met: (i) significant positive linear regression (P<0.05) between force and slope coefficient, (ii) an adjusted coefficient of determination for force versus slope coefficient relationship greater than 0.85, and (iii) a standard error for the EMG(FT) below 5% of MVC. The results showed the inability to determine an EMG(FT) in all of the 37 subjects from both RMS (9 out of 37 subjects) and MPF (27 out of 37 subjects). In addition, for the 12 subjects tested twice, the reproducibility of the EMG(FT) determination was weak (ICC=-0.029 and SEM=7.5% of MVC for EMG(FT) determined from MPF). The present results suggest that the EMG(FT) is not a valid tool to assess muscle function.
本研究旨在确定第一背侧骨间肌的肌电图（EMG）活动水平和 EMG 频率内容的肌电图疲劳阈值（EMG(FT)）。37 名健康受试者以随机顺序的最大自主收缩百分比（即 20%、25%、30%、35%、40%、50%和 60%）进行 7 次等长索引外展。在这些回合中，使用线性电极阵列（即 7 个 EMG 通道）在第一背侧骨间肌测量表面 EMG。对于每个受试者，如果满足以下标准，则从均方根（RMS）和平均功率频率（MPF）值确定 EMG(FT)：（i）力与斜率系数之间存在显著正线性回归（P<0.05），（ii）力与斜率系数关系的调整决定系数大于 0.85，以及（iii）EMG(FT)的标准误差低于 MVC 的 5%。结果表明，在所有 37 名受试者中，无法从 RMS（9 名受试者中有 9 名）和 MPF（37 名受试者中有 27 名）确定 EMG(FT)。此外，对于 12 名接受两次测试的受试者，EMG(FT)的重现性较弱（ICC=-0.029，对于从 MPF 确定的 EMG(FT)，SEM=7.5%MVC）。本研究结果表明，EMG(FT)不是评估肌肉功能的有效工具。
