Kamavuako Ernest Nlandu, Hennings Kristian, Farina Dario
Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7 D-3, DK-9220 Aalborg, Denmark.
Muscle Nerve. 2007 Aug;36(2):190-6. doi: 10.1002/mus.20801.
Normative values of muscle fiber conduction velocity depend on the conditions in which conduction velocity is measured due to the velocity recovery function (VRF) of muscle fibers. In this study the VRF of the compound muscle action potential (CMAP) was assessed following doublet and triplet stimulation in order to investigate the effect of repetitive muscle activation on muscle fiber conduction velocity. The VRF from doublet and triplet activation showed a peak of 4.6%-15.0% and 6.4%-25.9%, respectively, which is not significantly different. The VRF of the CMAP with doublet stimulation had a plateau between 25-75 ms, similar to that reported for single muscle fibers, and changed as a consequence of previous activation. The VRFs with doublet and triplet stimulation were different for interstimulus intervals in the range of 12-250 ms, where the triplet resulted in a plateau of supernormal conduction velocity. The VRF of the triplet could be explained by linear summation of the effects from doublet stimulations only for small distances between the two conditioning stimuli. These results provide new information on the adaptation of membrane properties of muscle fibers to repetitive activation. Changes in CMAP properties due to repeated activation may influence the accuracy of techniques based on CMAP recordings, such as collision methods.
由于肌纤维的速度恢复函数（VRF），肌纤维传导速度的标准值取决于测量传导速度的条件。在本研究中，通过双重刺激和三重刺激评估复合肌肉动作电位（CMAP）的VRF，以研究重复性肌肉激活对肌纤维传导速度的影响。双重刺激和三重刺激产生的VRF峰值分别为4.6%-15.0%和6.4%-25.9%，两者无显著差异。双重刺激时CMAP的VRF在25-75毫秒之间有一个平台期，类似于单根肌纤维的情况，并因先前的激活而发生变化。双重刺激和三重刺激的VRF在12-250毫秒的刺激间隔范围内有所不同，其中三重刺激导致超常传导速度的平台期。仅在两个条件刺激之间的距离较小时，三重刺激的VRF可以通过双重刺激效应的线性叠加来解释。这些结果为肌纤维膜特性对重复性激活的适应性提供了新信息。重复激活导致的CMAP特性变化可能会影响基于CMAP记录的技术（如碰撞法）的准确性。
