Model based sensitivity analysis of EMG-Force relation with respect to motor unit properties: Applications to muscle paresis in stroke
Model based sensitivity analysis of EMG-Force relation with respect to motor unit properties: Applications to muscle paresis in stroke
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DOI：
10.1007/s10439-007-9329-3
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发表时间：
2007-09-01
影响因子：
3.8
通讯作者：
Rymer, William Z.
中科院分区：
文献类型：
--
作者：
Zhou, Ping;Suresh, Nina L.;Rymer, William Z.
使用模拟方法，并通过应用现有的运动神经元池，肌肉力量，表面肌电图模型的肌电图（EMG）的力的关系，运动神经元和肌肉特性的变化的敏感性进行了探讨。仿真结果表明，几个因素有助于潜在的已知的变化，在肌无力中风肌肉的肌电-力的关系。首先，相对于注入电流的运动单元募集范围的压缩倾向于在给定力下产生更大的EMG振幅，并且产生高度非线性的EMG-力关系。EMG-力关系的总体平均斜率趋于平坦，主要是因为这种非线性行为。第二，随着平均运动单位放电率的降低，EMG-力关系的斜率也趋于增加，特别是当平均放电率大幅下降到运动单位融合频率以下时。最后，观察到类似的效果，减少运动单位的数量，并与运动单位收缩性能的变化，这也改变了肌电力的关系。这些发现为我们理解正常和病理状态下的实验肌电-力关系提供了新的见解，例如中风时paretis肌肉的异常肌电-力关系。
The sensitivity of the electromyogram (EMG)-force relation to changes in motoneuron and muscle properties was explored using a simulation approach, and by applying existing motoneuron pool, muscle force, and surface EMG models. The simulation results indicate that several factors contribute potently to known changes in the EMG-force relation in paretic stroke muscles. First, compression of the motor unit recruitment range with respect to the injected current tends to generate greater EMG amplitude at a given force, and to produce a highly nonlinear EMG-force relation. The overall mean slope of the EMG-force relation tends to be flatter, primarily because of this non-linear behavior. Second, with reductions of the mean motor unit firing rates, the slope of the EMG-force relation also tends to increase especially as the mean firing rates dropped substantially below the motor unit fusion frequency. Finally, similar effects were observed with a reduction in the number of motor units, and with variation in motor unit contractile properties, which also altered the EMG-force relation. These findings provide new insight toward our understanding of experimental EMG-force relations in both normal and pathological states, such as the abnormal EMG-force relations of paretis muscles in stroke.