Electrical impedance myography (EIM) is as an experimental technique that associates muscle impedance with muscular activity. Changes in muscle impedance during contraction occur mainly due to changes in the morphological and physiological characteristics of muscles that lead to different impeditivities in comparison with the resting condition. There is no consensus on the details of muscular impedance during muscle activity. EIM measurements on humans are also influenced by factors such as the electrode-skin interface, layers of skin and fat, and the connective tissue that can generate undesirable effects in the impedance signal. These effects can be avoided if EIM measurements are carried out directly on the muscle by using the models of animals. This study investigates changes in the EIM signal in the gastrocnemius muscles of Wistar rats during different levels of muscular contraction. In vivo experiments were conducted on 19 male rats. The muscle was exposed, fixed on a load cell, and electrically stimulated to evoke different levels of muscle contraction. Signals of the components of impedance were analyzed against the muscular force signal. The results show moderate correlations (p < 0.05) among the impedance-related parameters of resistance (r = -0.76), reactance (r = 0.57), and phase (r = 0.53). In addition to providing an experimental protocol for the invasive collection of data on electrical impedance to minimize problems associated with surface electrodes, this study shows that of the components of impedance, resistance is most affected by the intensity of muscular contractions and that morphological changes influence impedance mainly at low intensities.

中文翻译：

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大鼠腓肠肌不同程度收缩的侵入性电阻抗肌电图

电阻抗肌电图 (EIM) 是一种将肌肉阻抗与肌肉活动联系起来的实验技术。收缩期间肌肉阻抗的变化主要是由于肌肉的形态和生理特征的变化导致与静息状态相比具有不同的障碍。关于肌肉活动期间肌肉阻抗的细节还没有达成共识。对人体的 EIM 测量还受到诸如电极-皮肤界面、皮肤和脂肪层以及结缔组织等因素的影响，这些因素会在阻抗信号中产生不良影响。如果使用动物模型直接对肌肉进行 EIM 测量，则可以避免这些影响。本研究调查了不同程度的肌肉收缩期间 Wistar 大鼠腓肠肌中 EIM 信号的变化。对 19 只雄性大鼠进行了体内实验。肌肉暴露在外，固定在称重传感器上，并通过电刺激引起不同程度的肌肉收缩。针对肌力信号分析阻抗分量的信号。结果显示电阻 (r = -0.76)、电抗 (r = 0.57) 和相位 (r = 0.53) 的阻抗相关参数之间存在中等相关性 (p < 0.05)。除了为电阻抗数据的侵入性收集提供实验方案以最大程度地减少与表面电极相关的问题外，这项研究还表明阻抗的组成部分，