Development of new inverse analyses of surface EMG about change of neuromuscular structure and function with ageing

我们对表面肌电信号进行反向分析，以提取解剖和生理信息，如位置（深度）、电流强度、大小（半径）、肌纤维密度、活跃运动单元的招募和放电速率。通过表面MUAP逆分析可知，主动电机单元的深度为0.5-7.7mm，主动电机单元的电流强度为0.1-230.9nAm。此外，通过反向分析明确深度与电流强度的关系，估计运动单元的半径为1.4-5.4mm，运动单元的肌纤维密度为0.4-9.3纤维/mm2。此外，我们还开发了用于新的反分析的扩展电极阵列，以提高估计的准确性。表面肌电模拟结果表明，在低力快速收缩时，运动单元的招募数量比最大自主收缩时要少。但是，必须对包含运动单元模型的仿真方法进行扩展，以获取运动单元的射击统计信息。另一方面，通过有限元模拟，考察了表皮、真皮等非均匀组织和运动单元纤维密度对表面肌电电位的影响。结果表明，在上述条件下，电机单元深度的估计是鲁棒稳定的。本研究发展的逆分析方法的优点是，该方法能够估计活跃运动单元的深度、电流强度、大小、纤维密度和放电统计等解剖生理过程，而在许多运动单元的招募所产生的干扰条件下无法实际测量。为了收集更详细、更有效的神经肌肉系统信息，我们必须推进逆分析的发展，包括记录方法和仿真模型，并将这些方法应用于老年受试者。少

We examined the inverse analysis of surface EMG to extract anatomical and physiological information such as the position (depth),current strength, size (radius), muscle fiber density, recruitment and firing rate of active motor units. It became clear that the depth of the active motor units was 0.5-7.7mm, and the current strength of the active motor units was 0.1-230.9nAm, through the inverse analysis with surface MUAP. In addition, the radius of the motor units was 1.4-5.4mm, and the muscle fiber density of the motor units was 0.4-9.3fiber/mm2, was estimated through the relationships between depth and current strength that were clarified by the inverse analysis. Furthermore, we developed the extended electrode array for new inverse analysis to progress the accuracy of estimation. It was clarified that the number of recruitment of motor units in rapid contraction with low force was smaller than that in maximal voluntary contraction for EMG amplitude, from the simulation of surface EMG … More with the model that had anatomical and physiological parameters about motor unit. But, the simulation method including the model of motor units must be extended for information about firing statistics of the motor units. On the other hand, the effect of the inhomogenious tissue such as epidermis and dermis, and the fiber density of motor unit on the surface electromyo potential was examined through the simulation with finite element method. As the results, it was clarified that the estimate of depth of motor unit was robust and stable against the above conditions. The inverse analysis developed in this study have the advantage that this method is able to estimate the anatomical and physiological process such as the depth, current strength, size, fiber density and firing statistics of active motor units, which is not able to measure practically under the interfered condition produced by recruitment of many motor units. In order to collect more detail and effective information about neuromuscular system, we must progress the development of the inverse analysis including recording method and model for simulation, and application of those methods to aged subjects. Less