EXCITATION-FREQUENCY AND MUSCLE FATIGUE - ELECTRICAL RESPONSES DURING HUMAN VOLUNTARY AND STIMULATED CONTRACTIONS
EXCITATION-FREQUENCY AND MUSCLE FATIGUE - ELECTRICAL RESPONSES DURING HUMAN VOLUNTARY AND STIMULATED CONTRACTIONS
复制标题
DOI：
10.1016/0014-4886(79)90280-2
复制
发表时间：
1979-01-01
影响因子：
5.3
通讯作者：
WOODS, JJ
中科院分区：
文献类型：
--
作者：
BIGLANDRITCHIE, B;JONES, DA;WOODS, JJ
比较了人拇收肌电活动在疲劳最大自主收缩(MVC)和不同频率等周期最大尺神经刺激时的变化。每例患者均连续监测肌电(肌电)和肌电(SRE)，每隔一段时间测量诱发表面动作电位(SAP)的面积。在高频刺激(50和80 Hz)中，SRE和SAP面积在S的前10-20天都有所增加，之后下降到很低的值。对于低频刺激(20 HZ)，两者在整个收缩过程中都逐渐增加。SAP区的增加与传导速度减慢有关。在所有刺激频率恒定的实验中，SRE和SAP区域的变化相互反映。在持续MVC中，力量损失率低于高频刺激。周期性单次最大电击神经诱发的SAPS最初在面积上增加，但随后保持相对恒定。SRE不再与SAP平行；它通常最初是增加的，但后来大致成比例地下降。当以逐渐降低的频率(80~20赫兹)最大限度地刺激神经时，力量损失和SAP面积与MVC时所记录的相似。SRE在形式上也很相似。在持续的高频刺激中，大部分疲劳是由于电传播的失败造成的，可能主要是在肌肉纤维膜上。在没有观察到类似失败的外膜收缩中，肌肉疲劳通过运动单位激活的渐进性减少而最小化。
Changes in the electrical activity of the human adductor pollicis muscle during fatiguing maximal voluntary contractions (MVC) were compared to those resulting from equal periods of maximal ulnar nerve stimulation at different frequencies. In each case the force and smoothed, rectified (SRE) EMG (electromyogram) were monitored continuously, and the area of the evoked surface action potential (SAP) was measured at intervals. During high-frequency stimulation (50 and 80 Hz), both the SRE and SAP area increased in the first 10-20 s, thereafter declining to very low values. With low-frequency stimulation (20 HZ), both increased gradually throughout the contraction. The increases in SAP area were related to a slowing of conduction velocity. In all experiments in which the frequency of stimulation was constant, changes in the SRE and SAP area mirrored one another. In sustained MVC, the rate of force loss was less than during high-frequency stimulation. SAPs evoked by periodic single maximal shocks to the nerve increased initially in area but then remained relatively constant. The SRE no longer paralleled the SAP; it generally increased initially, but then declined roughly in proportion to the force. When the nerve was maximally stimulated at a progressively reduced frequency (80 to 20 Hz), force loss and SAP area were similar to those recorded during an MVC. The SRE was also similar in form. During continuous high-frequency stimulation, much of the fatigue is due to failure of electrical propagation, probably largely at the muscle fiber membrane. In vountary contractions where no similar failure was observed, muscle fatigue is minimized by a progressive reduction in motor unit activation.