Robust Identification of Motor Unit Discharges From High-Density Surface EMG in Dynamic Muscle Contractions of the Tibialis Anterior
Robust Identification of Motor Unit Discharges From High-Density Surface EMG in Dynamic Muscle Contractions of the Tibialis Anterior
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DOI：
10.1109/access.2021.3107283
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发表时间：
2021
期刊：
影响因子：
3.9
通讯作者：
H. Yokoyama;Atsushi Sasaki;Naotsugu Kaneko;Akira Saito;K. Nakazawa
中科院分区：
文献类型：
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作者：
H. Yokoyama;Atsushi Sasaki;Naotsugu Kaneko;Akira Saito;K. Nakazawa
运动单位 (MU) 活动的研究提供了神经肌肉控制的基本信息。基于盲源分离技术 (BSS) 的高密度表面肌电图 (HDsEMG) 分解已被用来估计 MU 的放电模式。 HDsEMG 信号的分解技术最初是针对等长收缩提出的。最近，分解方法已被用于非等长肌肉收缩。然而，肌电图分解技术可接受的动态肌肉收缩水平仍然是一个悬而未决的研究问题。因此，在本研究中，我们通过将合成的 MU 尖峰训练与实验确定的 MU 动作电位 (MUAP) 进行卷积来研究 EMG 分解方法在胫骨前肌 (TA) 肌肉动态肌肉收缩中的鲁棒性，该方法根据踝关节角度而变化。我们发现踝关节活动度 (ROM) 高达 20° 的动态收缩的分解精度与等长收缩时的分解精度相当。当踝关节活动度大于 20° 时，由于关节角度变化而导致的 MU 的不连续识别（即错误识别）尖峰时间明显大于等长收缩期间的尖峰时间。然而，当踝关节活动度达到30°时，由于踝关节角度变化导致的误识别率仍然低于5%。此外，我们发现踝关节活动度的增加减少了已识别的 MU 总数。根据结果，传统的 EMG 分解方法可能适用于 TA 中踝关节 ROM 为 30° 的动态收缩。
Investigation of motor unit (MU) activity provides a fundamental information of neuromuscular control. High density surface electromyogram (HDsEMG) decomposition based on the blind source separation techniques (BSS) has been performed to estimate discharge patterns of MUs. The decomposition techniques for HDsEMG signals were initially proposed for isometric contractions. Recently, the decomposition methods have been utilized for non-isometric muscle contractions. However, what level of dynamic muscle contraction is acceptable for the EMG decomposition techniques is still an open research problem. Thus, in the present study, we investigated the robustness of the EMG decomposition method in dynamic muscle contractions in the tibialis anterior (TA) muscle using a validation method of EMG decomposition by convolving the synthetic MU spike trains with experimentally identified MU action potentials (MUAPs), which change depending on the ankle joint angle. We found that the decomposition accuracy for dynamic contractions with ankle range of motion (ROM) up to 20° was comparable to that during isometric contraction. When ankle ROM was larger than 20°, discontinuously identified (i.e., misidentified) spike timings of MUs due to joint angle changes was significantly larger than those during isometric contraction. However, rate of misidentification due to ankle joint angle change was still lower than 5% up to ankle ROM of 30°. Additionally, we found that increase of ankle ROM decreased total number of identified MUs. Based on the results, the conventional EMG decomposition method is probably applicable for dynamic contractions with ankle ROM of 30° in TA.