Arabadzhiev Todor I, Dimitrov Vladimir G, Dimitrov George V
Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Acad. Georgi Bonchev Str., Block 21, 1113, Sofia, Bulgaria,
Eur J Appl Physiol. 2014 Aug;114(8):1645-55. doi: 10.1007/s00421-014-2893-y. Epub 2014 May 1.
To test the validity of using the increase in surface EMG as a measure of neural adaptation during the early gains in strength.
Simulation of EMG signals detected by surface bipolar electrode with 20-mm inter-pole distance at different radial distances from the muscle and longitudinal distances from the end-plate area. The increases in the root mean square (RMS) of the EMG signal due to possible alteration in the neural drive or elevation of the intracellular negative after-potentials, detected in fast fatigable muscle fibres during post-tetanic potentiation and assumed to accompany post-activation potentiation, were compared.
Lengthening of the intracellular action potential (IAP) profile due to elevation of the negative after-potentials could affect amplitude characteristics of surface EMG detected at any axial distance stronger than alteration in the neural drive. This was irrespective of the fact that the elevation of IAP negative after-potential was applied to fast fatigable motor units (MUs) only, while changes in frequency of activation (simulating neural drive changes) were applied to all MUs. In deeper muscles, where the fibre-electrode distance was larger, the peripheral effect was more pronounced. The normalization of EMG amplitude characteristics to an M-wave one could result only in partial elimination of peripheral factor influence
The increase in RMS of surface EMG during the early gains in strength should not be directly related to the changes in the neural drive. The relatively small but long-lasting elevated free resting calcium after high-resistance strength training could result in force potentiation and EMG increase.
验证在力量早期增长过程中，将表面肌电图（EMG）的增加作为神经适应性的一种测量方法的有效性。
模拟通过双极表面电极检测到的肌电信号，该电极极间距离为20毫米，位于距肌肉不同径向距离和距终板区不同纵向距离处。比较在强直后增强期间快速疲劳肌纤维中检测到的、因神经驱动可能改变或细胞内负后电位升高（假定伴随激活后增强）而导致的EMG信号均方根（RMS）的增加。
由于负后电位升高导致的细胞内动作电位（IAP）波形延长，对在任何轴向距离检测到的表面EMG幅度特征的影响，比神经驱动改变的影响更强。这与以下事实无关：IAP负后电位的升高仅应用于快速疲劳运动单位（MU），而激活频率的变化（模拟神经驱动变化）应用于所有MU。在纤维与电极距离较大的深层肌肉中，外周效应更为明显。将EMG幅度特征归一化为M波特征只能部分消除外周因素的影响。
在力量早期增长过程中，表面EMG的RMS增加不应直接与神经驱动的变化相关。高阻力力量训练后相对较小但持续时间长的游离静息钙升高可能导致力量增强和EMG增加。
