Laboratory for Engineering of the Neuromuscular System (LISiN), Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino Torino, Italy.
Front Physiol. 2013 Dec 13;4:367. doi: 10.3389/fphys.2013.00367. eCollection 2013.
In this study we investigated whether the spatial distribution of surface electromyographic (EMG) amplitude can be used to describe the activation of muscle portions with different biomechanical actions. Ten healthy subjects performed isometric contractions aimed to selectively activate a number of forearm muscles or muscle subportions. Monopolar electromyographic signals were collected with an electrode grid of 128 electrodes placed on the proximal, dorsal portion of the forearm. The monopolar EMG amplitude [root mean square (RMS) value] distribution was calculated for each contraction, and high-amplitude channels were identified through an automatic procedure; the position of the EMG source was estimated with the barycenter of these channels. Each of the contractions tested was associated to a specific EMG amplitude distribution, whose location in space was consistent with the expected anatomical position of the main agonist muscle (or subportion). The position of each source was significantly different from the others in at least one direction (ANOVA; transversally to the forearm: P < 0.01, F = 125.92; longitudinally: P < 0.01, F = 35.83). With such an approach, we could distinguish the spatial position of EMG distributions related to the activation of contiguous muscles [e.g., extensor carpi ulnaris (ECU) and extensor digitorum communis (EDC)], different heads of the same muscle (i.e., extensor carpi radialis (ECR) brevis and longus) and different functional compartments (i.e., EDC, middle, and ring fingers). These findings are discussed in terms of how forces along a given direction can be produced by recruiting population of motor units clustered not only in specific muscles, but also in muscle sub-portions. In addition, this study supports the use of high-density EMG systems to characterize the activation of muscle subportions with different biomechanical actions.
在这项研究中，我们研究了表面肌电图（EMG）幅度的空间分布是否可用于描述具有不同生物力学作用的肌肉部分的激活。 10 名健康受试者进行了等长收缩，旨在选择性地激活一些前臂肌肉或肌肉亚部。使用放置在前臂近端，背部的 128 个电极网格采集单极肌电图信号。为每个收缩计算了单极 EMG 幅度（均方根（RMS）值）分布，并通过自动程序识别高幅度通道；通过这些通道的重心来估计 EMG 源的位置。测试的每个收缩都与特定的 EMG 幅度分布相关联，其在空间中的位置与主要激动肌（或亚部）的预期解剖位置一致。在至少一个方向上，每个源的位置都明显不同于其他位置（ANOVA; 横向于前臂：P <0.01，F = 125.92; 纵向：P <0.01，F = 35.83）。通过这种方法，我们可以区分与连续肌肉激活相关的 EMG 分布的空间位置[例如，尺侧腕伸肌（ECU）和指伸肌（EDC）]，同一肌肉的不同头部（即，桡侧腕伸肌（ECR）短和长）和不同的功能区（即，EDC，中指和环指）。这些发现从以下方面进行了讨论：如何通过募集不仅位于特定肌肉中，而且还位于肌肉亚部中的运动单位群来产生沿给定方向的力。此外，这项研究支持使用高密度 EMG 系统来描述具有不同生物力学作用的肌肉亚部的激活。
