Are the myoelectric manifestations of fatigue distributed regionally in the human medial gastrocnemius muscle?
Are the myoelectric manifestations of fatigue distributed regionally in the human medial gastrocnemius muscle?
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DOI：
10.1016/j.jelekin.2011.08.006
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发表时间：
2011-12-01
影响因子：
2.5
通讯作者：
Vieira, Taian M. M.
中科院分区：
文献类型：
--
作者：
Gallina, Alessio;Merletti, Roberto;Vieira, Taian M. M.
肌电疲劳通常表现为表面肌电图（EMG）的幅度和频谱的变化。有趣的是，这些变化似乎在不同的肌肉中局部表现出来。在这项研究中，我们问这样的区域分布的肌电疲劳是否延伸到内侧腓肠肌（MG）肌肉。如果MG肌肉在疲劳收缩期间被局部激活，或者如果最易疲劳的MG纤维位于不同的肌肉区域，则预期MG疲劳的肌电表现局部地出现在表面电极的网格中。与矩阵的表面电极（7 × 15单差分肌电图），我们表明，肌电疲劳，的确，体现在区域MG肌肉的12名受试者，谁施加间歇性，疲劳足底屈曲在50%的最大努力。与均方根振幅相反，在整个足底屈曲过程中，受试者的表面EMG的中位频率变化一致（P = 0.002）。平均而言，在矩阵中的105个通道中，EMG频谱的变化在78-93（四分位数间隔）处表示，尽管通道之间的变化程度不同。对于所有参与者，与矩阵中的所有通道相比，约29%的通道检测到中值频率显著更大的降低（P < 0.003）。引人注目的是，这些通道并不是稀疏分布的;它们占据了受试者的局部皮肤区域。生理上，我们的研究结果表明，在次最大疲劳任务，肌电表现的MG疲劳的空间局部肌肉区域。从技术上讲，研究MG肌肉中肌电疲劳的可能性似乎取决于电极位置。(C)2011爱思唯尔有限公司保留所有权利。
Myoelectric fatigue typically manifests as variations in the amplitude and spectrum of surface electromyograms (EMGs). Interestingly, these variations seem to be represented locally in different muscles. In this study, we ask whether such a regional distribution of myoelectric fatigue extends to the medial gastrocnemius (MG) muscle. If the MG muscle is activated locally during fatiguing contractions, or if the most fatigable MG fibers are located at distinct muscle regions, then, the myoelectric manifestations of MG fatigue are expected to appear locally in a grid of surface electrodes. With a matrix of surface electrodes (7 x 15 single-differential EMGs) we show that myoelectric fatigue, indeed, manifests regionally in the MG muscle of 12 subjects, who exerted intermittent, fatiguing plantar flections at 50% of their maximal effort. Contrary to the root mean square amplitude, the median frequency of surface EMGs varied consistently across subjects throughout the plantar flections (P = 0.002). On average, changes in EMG spectrum were represented at 78-93 (interquartile interval) out of the 105 channels in the matrix, though with different degrees across channels. For all participants, about 29% of the channels detected significantly greater reductions in median frequency when compared to all channels in the matrix (P < 0.003). Strikingly, these channels were not sparsely distributed; they rather occupied localized skin regions across subjects. Physiologically, our results suggest that, during sub-maximal fatiguing tasks, myoelectric manifestations of MG fatigue are represented in spatially localized muscle regions. Technically, the possibility of studying myoelectric fatigue in the MG muscle appears to depend on the electrode location. (C) 2011 Elsevier Ltd. All rights reserved.