Assessment of low back muscle fatigue by surface EMG signal analysis: methodological aspects
Assessment of low back muscle fatigue by surface EMG signal analysis: methodological aspects
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DOI：
10.1016/s1050-6411(03)00040-3
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发表时间：
2003-08-01
影响因子：
2.5
通讯作者：
Merletti, R
中科院分区：
文献类型：
--
作者：
Farina, D;Gazzoni, M;Merletti, R
本文重点讨论了与表面肌电图（EMG）信号检测有关的方法学问题。特别是，我们分析了（1）从这些肌肉检测到的信号的特性（在传播分量方面）;（2）电极位置对从表面EMG提取的变量的影响;（3）电极间距离（IED）对相同变量的影响;（4）在高和非常低的力水平收缩期间评估疲劳的可能性。为了解决这些问题，我们检测单差分表面肌电信号阵列的8个电极从6个位置上的两侧的脊柱，在水平的第一（L1），第二（L2），和第五（L5）腰椎。在高和低的力量，短和长时间的收缩过程中，共获得42个表面肌电通道。主要结果如下：（1）信号质量差，非行进分量占优势;（2）由于点（1），在大多数情况下，不可能可靠地估计肌纤维传导速度;（3）尽管信号质量差，但可以区分所研究肌肉的疲劳特性和不同收缩水平下的疲劳性;（4）IED影响表面肌电变量对电极位置的敏感性，在进行频谱和振幅分析时，建议使用较大的IED：（5）表面肌电变量对电极位置变化的敏感性平均大于结构不太复杂的其他肌肉;（6）IED影响振幅初值、斜率和谱变量初值;（7）幅度和频谱变量的归一化斜率不受IED的影响，因此建议用于不同姿势或运动期间的疲劳分析，当IED在不同条件下可能发生变化时（在分离电极的情况下）;（8）在振幅和频谱分析的全局水平下的表面EMG技术不能用于表征在非常低水平、长持续时间收缩期间的下背部肌肉的疲劳特性，因为在这些情况下，不稳定的MU池对EMG变量具有主要影响。这些考虑澄清了过去研究中仅部分研究的问题。上述局限性很重要，在临床实践中将表面肌电图结果作为腰背肌评估的一种手段时，应仔细讨论。(C)2003爱思唯尔科技有限公司版权所有。
This paper focuses on methodological issues related to surface electromyographic (EMG) signal detection from the low back muscles. In particular, we analysed (1) the characteristics (in terms of propagating components) of the signals detected from these muscles; (2) the effect of electrode location on the variables extracted from surface EMG; (3) the effect of the inter-electrode distance (IED) on the same variables; (4) the possibility of assessing fatigue during high and very low force level contractions. To address these issues, we detected single differential surface EMG signals by arrays of eight electrodes from six locations on the two sides of the spine, at the levels of the first (L1), the second (L2), and the fifth (L5) lumbar vertebra. In total, 42 surface EMG channels were acquired at the same time during both high and low force, short and long duration contractions. The main results were: (1) signal quality is poor with predominance of non-travelling components; (2) as a consequence of point (1), in the majority of the cases it is not possible to reliably estimate muscle fiber conduction velocity; (3) despite the poor signal quality, it was possible to distinguish the fatigue properties of the investigated muscles and the fatigability at different contraction levels; (4) IED affects the sensitivity of surface EMG variables to electrode location and large IEDs are suggested when spectral and amplitude analysis is performed; (5) the sensitivity of surface EMG variables to changes in electrode location is on average larger than for other muscles with less complex architecture; (6) IED influences amplitude initial values and slopes, and spectral variable initial values; (7) normalized slopes for both amplitude and spectral variables are not affected by IED and, thus, are suggested for fatigue analysis at different postures or during movement, when IED may change in different conditions (in case of separated electrodes); (8) the surface EMG technique at the global level of amplitude and spectral analysis cannot be used to characterize fatigue properties of low back muscles during very low level, long duration contractions since in these cases the non-stable MU pool has a major influence on the EMG variables. These considerations clarify issues only partially investigated in past studies. The limitations indicated above are important and should be carefully discussed when presenting surface EMG results as a means for low back muscle assessment in clinical practice. (C) 2003 Elsevier Science Ltd. All rights reserved.