Department of Health and Exercise Science, Biophysics Laboratory, University of Oklahoma, Norman, Oklahoma, USA.
J Electromyogr Kinesiol. 2010 Oct;20(5):787-94. doi: 10.1016/j.jelekin.2010.01.004. Epub 2010 Feb 21.
This study examined the log-transformed mechanomyographic (MMG(RMS)) and electromyographic (EMG(RMS)) amplitude vs. force relationships for aerobically-trained (AT), resistance-trained (RT), and sedentary (SED) individuals. Subjects performed isometric ramp contractions from 5% to 90% maximal voluntary contraction. Muscle biopsies were collected and thigh skinfolds, MMG and EMG were recorded from the vastus lateralis muscle. Linear regression models were fit to the log-transformed EMG(RMS) and MMG(RMS) vs. force relationships. The slope (b coefficient) and the antilog of the y-intercept (a coefficient) were calculated. The AT group had the highest percentage of type I fiber area, the RT group had the highest percentage of type IIa fiber area, and the SED group had the highest percentage of type IIx fiber area. The a coefficients were higher for the AT group than the RT and SED groups in both the MMG(RMS) and EMG(RMS) vs. force relationships, whereas the b coefficients were lower for the AT group than the RT and SED groups only in the MMG(RMS) vs. force relationship. The group differences among the a coefficients may have reflected subcutaneous fat acting as a filter thereby reducing EMG(RMS) and MMG(RMS). The lower b coefficients for the AT group in the MMG(RMS) patterns may have reflected fiber area-related differences in motor unit activation strategies.
本研究考察了有氧训练（AT）、抗阻训练（RT）和久坐（SED）个体的肌动描记图（MMG(RMS)）和肌电图（EMG(RMS)）幅度与力量的对数关系。受试者进行了从 5%到 90%最大随意收缩的等长斜坡收缩。从股外侧肌采集肌肉活检，并记录大腿皮褶、MMG 和 EMG。将对数转换后的 EMG(RMS)和 MMG(RMS)与力量关系拟合线性回归模型。计算斜率（b 系数）和 y 截距的反对数（a 系数）。AT 组具有最高的 I 型纤维面积百分比，RT 组具有最高的 IIa 型纤维面积百分比，SED 组具有最高的 IIx 型纤维面积百分比。在 MMG(RMS)和 EMG(RMS)与力量关系中，AT 组的 a 系数高于 RT 和 SED 组，而仅在 MMG(RMS)与力量关系中，AT 组的 b 系数低于 RT 和 SED 组。a 系数中的组间差异可能反映了皮下脂肪作为一种过滤器，从而降低了 EMG(RMS)和 MMG(RMS)。在 MMG(RMS)模式中，AT 组的 b 系数较低可能反映了运动单位激活策略与纤维面积相关的差异。
