Ryan Eric D, Cramer Joel T, Housh Terry J, Beck Travis W, Herda Trent J, Hartman Michael J
Department of Health and Exercise Science, Biophysics Laboratory, University of Oklahoma, 1401 Asp Avenue, Norman, OK 73019-6081, USA.
J Neurosci Methods. 2007 Apr 15;161(2):212-9. doi: 10.1016/j.jneumeth.2006.11.007. Epub 2006 Dec 21.
The purpose of this study was to examine the inter-individual variability for the patterns of responses for mechanomyographic (MMG) amplitude and mean power frequency (MPF) versus isometric torque in lower-strength (LS) and higher-strength (HS) individuals. Twelve participants (mean +/- S.D. age = 25 + 4 years) performed two isometric maximal voluntary contractions (MVCs) before and after completing nine submaximal step muscle actions (15%, 25%, 35%, 45%, 55%, 65%, 75%, 85%, and 95% MVC) of the right leg extensors. MMG signals were recorded from the vastus lateralis muscle, and MMG amplitude and MPF values were computed for each corresponding percentage of the MVC. Polynomial regression analyses indicated that the composite MMG amplitude versus isometric torque relationship was best fit with a linear model (r(2) = 0.980) for the LS group and a cubic model (r(2) = 0.994) for the HS group. The composite MMG MPF versus isometric torque relationships were best fit with linear models for both the LS (r(2) = 0.529) and HS (r(2)=0.591) groups. However, only 66% of the individuals exhibited the same linear MMG amplitude patterns as the composite relationship for the LS group, whereas only 33% of the individual relationships were cubic for the HS group. Only one subject exhibited a positive linear (r(2) = 0.681) relationship for the MMG(MPF) versus isometric torque relationship for either the LS or HS groups. These findings suggested that strength differences do not affect the patterns of responses for MMG amplitude or MPF. The lack of consistency between the individual and composite patterns of responses suggested some degree of inter-individual variability. Therefore, future studies should examine the individual patterns of response to draw conclusions about motor control strategies.
本研究的目的是检验低强度（LS）和高强度（HS）个体中，肌机械图（MMG）振幅和平均功率频率（MPF）与等长扭矩反应模式的个体间差异。12名参与者（平均±标准差年龄 = 25 ± 4岁）在完成右腿伸肌的9次次最大阶梯式肌肉动作（15%、25%、35%、45%、55%、65%、75%、85%和95%最大自主收缩[MVC]）之前和之后，进行了两次等长最大自主收缩（MVC）。从股外侧肌记录MMG信号，并针对每个相应的MVC百分比计算MMG振幅和MPF值。多项式回归分析表明，LS组的复合MMG振幅与等长扭矩关系最适合线性模型（r² = 0.980），而HS组最适合三次模型（r² = 0.994）。LS组（r² = 0.529）和HS组（r² = 0.591）的复合MMG MPF与等长扭矩关系均最适合线性模型。然而，只有66%的个体表现出与LS组复合关系相同的线性MMG振幅模式，而HS组只有33%的个体关系为三次模式。对于LS组或HS组，只有一名受试者的MMG（MPF）与等长扭矩关系呈现正线性（r² = 0.681）关系。这些发现表明，力量差异不会影响MMG振幅或MPF的反应模式。个体与复合反应模式之间缺乏一致性表明存在一定程度的个体间差异。因此，未来的研究应检查个体反应模式，以得出关于运动控制策略的结论。
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