Aim

This study aims to simultaneously record the magnetic and electric components of the propagating muscular action potential.

Method

A single-subject study of the monosynaptic stretch reflex of the musculus rectus femoris was performed; the magnetic field generated by the muscular activity was recorded in all three spatial directions by five optically pumped magnetometers. In addition, the electric field was recorded by four invasive fine-wire needle electrodes. The magnetic and electric fields were compared by modelling the muscular anatomy of the rectus femoris muscle and by simulating the corresponding magnetic field vectors.

Results

The magnetomyography (MMG) signal can reliably be recorded following the stimulation of the monosynaptic stretch reflex. The MMG signal shows several phases of activity inside the muscle, the first of which is the propagating muscular action potential. As predicted by the finite wire model, the magnetic field vectors of the propagating muscular action potential are generated by the current flowing along the muscle fiber. Based on the magnetic field vectors, it was possible to reconstruct the pinnation angle of the muscle fibers. The later magnetic field components are linked to the activation of the contractile apparatus.

Interpretation

MMG allows to analyze the muscle physiology from the propagating muscular action potential to the initiation of the contractile apparatus. At the same time, this methods reveals information about muscle fiber direction and extend. With the development of high-resolution magnetic cameras, that are based on OPM technology, it will be possible to image the function and structure of the biomagnetic field of any skeletal muscle with high precision. This method could be used both, in clinical medicine and also in sports science.

中文翻译：

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通过光泵磁力计研究肌肉动作电位的时间和空间动态

目标

本研究旨在同时记录传播肌肉动作电位的磁和电分量。

方法

对股直肌的单突触牵张反射进行了单受试者研究；五个光泵磁力计在所有三个空间方向上记录了肌肉活动产生的磁场。此外，电场由四个侵入性细线针电极记录。通过模拟股直肌的肌肉解剖结构并模拟相应的磁场矢量，比较了磁场和电场。

结果

在刺激单突触牵张反射后，可以可靠地记录肌电图 (MMG) 信号。MMG 信号显示肌肉内活动的几个阶段，第一个阶段是传播的肌肉动作电位。正如有限线模型所预测的那样，传播肌肉动作电位的磁场矢量是由沿肌肉纤维流动的电流产生的。基于磁场矢量，可以重建肌肉纤维的羽化角。后面的磁场分量与收缩装置的激活有关。

口译

MMG 允许分析从传播肌肉动作电位到收缩装置启动的肌肉生理学。同时，该方法揭示了有关肌纤维方向和伸展的信息。随着基于OPM技术的高分辨率磁性相机的发展，可以高精度地对任何骨骼肌的生物磁场的功能和结构进行成像。这种方法既可用于临床医学，也可用于运动科学。