Human Performance Laboratory, The University of Calgary, Alberta, Calgary, Canada.
J Electromyogr Kinesiol. 1997 Jun;7(2):113-21. doi: 10.1016/s1050-6411(96)00023-5.
The effects of length changes in the in-situ cat soleus muscle on vibromyographic (VMG) signals were assessed using electrical stimulation of the soleus nerve in three adult male cats. Force and VMG signals were measured using an E-shaped force transducer and a miniature, unidirectional accelerometer, respectively. In each test, the soleus nerve was stimulated for 6 s at rates ranging from 4 to 35 Hz, and at two to four ankle angles (80-140 degrees ). The force of the soleus muscle increased with increasing muscle length and stimulation rates. For a given sub-tetanic frequency of stimulation, the root mean square (RMS) values of the VMG signal were larger at intermediate muscle lengths than at both the longest and the shortest muscle lengths. There was a continuous increase in the RMS of the VMG signal with decreasing muscle length when the contraction was tetanic. There was a trend towards an increase in the median frequency (MDF) of the VMG signal with increasing muscle length. The results of this study support the idea that the amplitude and frequency content of the VMG signal during electrically elicited muscle contractions are directly affected by changes in the mechanical properties (i.e. the stiffness and the active and passive tension) of muscle caused by length changes.
采用电刺激猫比目鱼肌神经的方法，研究了原位比目鱼肌长度变化对振动肌电图（VMG）信号的影响。在三个成年雄性猫中，使用 E 型力传感器和微型单向加速度计分别测量力和 VMG 信号。在每次测试中，刺激比目鱼肌神经 6 s，刺激频率范围为 4-35 Hz，踝关节角度范围为 80-140 度。比目鱼肌的力随着肌肉长度和刺激频率的增加而增加。在给定的亚收缩频率刺激下，中间肌肉长度的 VMG 信号的均方根（RMS）值大于最长和最短肌肉长度的 RMS 值。当收缩为强直时，VMG 信号的 RMS 值随肌肉长度的减小而连续增加。VMG 信号的中值频率（MDF）随肌肉长度的增加呈上升趋势。本研究的结果支持这样一种观点，即电诱发肌肉收缩过程中 VMG 信号的幅度和频率内容直接受到肌肉机械特性（即刚度和主动及被动张力）变化的影响，这些变化是由长度变化引起的。
