Background

Even though most studies normalize the surface EMG signal of the gastrocnemius muscle using a single position of maximum voluntary isometric contraction (MVIC), several studies tend to indicate that several positions are in fact needed to obtain a maximal voluntary activation (MVA) for most of the subjects. However, no combination of positions has already been described.

Research question

A combination of MVIC positions to normalize the EMG signal of the gastrocnemius muscle is investigated. the influence of using several positions on the reproducibility of the normalization process is evaluated.

Methods

Twenty healthy volunteers (45 % female – 55 % male, 25.4 years (SD 4.3), 72.6 kg (SD 13.9), 1.78 m (SD 0.12)) were recruited. Six positions for MVIC were compared and the effect of several normalization combinations on a functional task (gait) was evaluated.

Results

Several positions are needed to obtain at least 90 % of the MVA for 90 % of the volunteers even though the use of a single well-chosen position (unipodal standing position with knee fully extended and ankle fully plantar-flexed) will lead to no statistically significant differences of the gait evaluation during stance phase. For each position, five repetitions of the MVIC are recommended to obtain a valid MVA.

Significance

This study confirms that using several MVIC positions is recommended when possible to normalize the gastrocnemius muscle EMG signal. However, in the situation of a patient where limited MVIC attempts are possible, using a single well-chosen position should not significantly influence the amplitude and the reproducibility of the measures.

中文翻译：

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腓肠肌肌电信号正常化：考虑到重现性的年轻人的最佳自愿最大等距收缩试验。

背景

即使大多数研究使用最大自愿等距收缩（MVIC）的单个位置使腓肠肌的表面EMG信号正常化，但一些研究倾向于表明实际上对于大多数人来说，需要获得最大自愿激活（MVA）的几个位置这个科目。但是，尚未描述位置的组合。

研究问题

研究了MVIC位置的组合以规范腓肠肌的肌电信号。评估使用多个位置对归一化过程可重复性的影响。

方法

招募了20名健康志愿者（女性占45％，男性占55％，25.4岁（标准差4.3），72.6千克（标准差13.9），1.78 m（标准差0.12））。比较了MVIC的六个位置，并评估了几种标准化组合对功能性任务（步态）的影响。

结果

即使使用单个精心选择的姿势（单足站立姿势，膝盖完全伸展而脚踝完全plant屈），也需要几个姿势才能获得90％的志愿者至少90％的MVA。站立阶段步态评估的显着差异。对于每个位置，建议重复五次MVIC以获取有效的MVA。

意义

这项研究证实，在可能的情况下，建议使用多个MVIC位置来使腓肠肌肌电信号正常化。但是，在患者可能进行有限的MVIC尝试的情况下，使用单一选择的位置不会显着影响测量的幅度和可重复性。