Mealing D, Long G, McCarthy P W
Anglo-European College of Chiropractic, Bournemouth, United Kingdom.
Br J Sports Med. 1996 Mar;30(1):27-31. doi: 10.1136/bjsm.30.1.27.
To determine the relation between the vibromyographic (VMG) frequency characteristics and fibre composition in postural and non-postural human muscle undergoing a standardised voluntary contraction.
Two human muscles with different fibre compositions [soleus: postural, mainly type I (slow) fibres; biceps brachii: non-postural, mixed type I and II (fast) fibres] were recorded from 18 healthy males isometrically contracting at 50% of their maximum voluntary contraction (MVC). Muscle vibrations were recorded using a contact microphone and the frequency content of the signals calculated using fast fourier transform algorithms.
The non-postural biceps brachii showed predominantly bimodal power spectra with significantly increased power in the 10-30 Hz bands (P < 0.01), as compared with soleus recordings which tended to be unimodal, with the majority of power below 10 Hz.
Muscles with a large proportion of type I fibres generate VMG signals which contain an increased percentage of low frequencies as compared to muscles with a mixed population of type I and type II fibres. The VMG appears to be generated, in part at least, by the mechanical twitching of motor units within the muscle; frequency domain analysis of this signal may provide a non-invasive measure of muscle fibre composition.
确定在进行标准化随意收缩时，人体姿势肌和非姿势肌的肌振动图（VMG）频率特征与纤维组成之间的关系。
从18名健康男性身上记录两块纤维组成不同的肌肉[比目鱼肌：姿势肌，主要为I型（慢）纤维；肱二头肌：非姿势肌，I型和II型（快）纤维混合]在最大随意收缩（MVC）的50%时进行等长收缩的情况。使用接触式麦克风记录肌肉振动，并使用快速傅里叶变换算法计算信号的频率成分。
与比目鱼肌记录结果倾向于单峰且大部分功率低于10Hz相比，非姿势性的肱二头肌主要表现为双峰功率谱，在10 - 30Hz频段功率显著增加（P < 0.01）。
与I型和II型纤维混合的肌肉相比，I型纤维比例高的肌肉产生的VMG信号中低频成分的百分比增加。VMG似乎至少部分是由肌肉内运动单位的机械抽搐产生的；对该信号进行频域分析可能提供一种非侵入性的肌肉纤维组成测量方法。
