Leonard C T, Kane J, Perdaems J, Frank C, Graetzer D G, Moritani T
Physical Therapy Department, University of Montana, Missoula 59812.
Electroencephalogr Clin Neurophysiol. 1994 Jun;93(3):209-17. doi: 10.1016/0168-5597(94)90042-6.
H reflex amplitudes, an indirect measure of the excitability of the alpha motoneuron pool, were recorded from 10 males during fatigue induced by submaximal, isotonic, voluntary contractions of the soleus muscle. H reflex changes were correlated with electromyographic changes (mean power frequency (MPF); root mean square (rms EMG)), under ischemic and non-ischemic conditions. The purpose of the ischemia was to block transmission of Ia and possibly Ib afferents to assess whether changes in sensory feedback had any effect on alpha motoneuron and EMG activity during fatigue. Significant interactions were found between ischemic and non-ischemic conditions. After an initial decrease (1.21 +/- 0.56 mV to 0.54 +/- 0.39 mV), H reflex amplitudes increased during non-ischemic trials (0.54 +/- 0.39 mV to 1.13 +/- 0.84 mV). Under ischemic conditions H reflex amplitudes decreased (2.11 +/- 1.10 mV to 0.70 +/- 0.74 mV; P < 0.003). During non-ischemic conditions, MPF decreased across 5 consecutive trials (157.7 +/- 17.9 Hz to 124.7 +/- 17.2 Hz), as compared to an increase under ischemic conditions (132.8 +/- 21.2 Hz to 197.1 +/- 53.6 Hz; P < 0.001). Root mean square amplitude decreased during the non-ischemic trials (31.07 +/- 14.62 mV to 25.98 +/- 8.26 mV). A greater decrease was noted during the ischemic trials (34.00 +/- 23.61 mV to 4.95 +/- 3.77 mV; P < 0.001). Data suggest that the CNS modulates muscle contraction in order to preserve force output and neuromuscular transmission during fatigue. This modulation appears dependent on Ia and/or Ib afferent feedback.
在比目鱼肌进行次最大等张随意收缩诱导疲劳过程中，对10名男性记录了H反射波幅，它是α运动神经元池兴奋性的一种间接测量指标。在缺血和非缺血条件下，将H反射变化与肌电图变化（平均功率频率（MPF）；均方根肌电图（rms EMG））进行关联。缺血的目的是阻断Ia和可能的Ib传入纤维的传导，以评估感觉反馈的变化在疲劳期间是否对α运动神经元和肌电图活动有任何影响。在缺血和非缺血条件之间发现了显著的相互作用。在非缺血试验中，H反射波幅在最初下降（从1.21±0.56 mV降至0.54±0.39 mV）后增加（从0.54±0.39 mV升至1.13±0.84 mV）。在缺血条件下，H反射波幅下降（从2.11±1.10 mV降至0.70±0.74 mV；P<0.003）。在非缺血条件下，MPF在连续5次试验中下降（从157.7±17.9 Hz降至124.7±17.2 Hz），相比之下，在缺血条件下则增加（从132.8±21.2 Hz升至197.1±53.6 Hz；P<0.001）。在非缺血试验中均方根波幅下降（从31.07±14.62 mV降至25.98±8.26 mV）。在缺血试验中下降幅度更大（从34.00±23.61 mV降至4.95±3.77 mV；P<0.001）。数据表明，中枢神经系统在疲劳期间调节肌肉收缩，以保持力量输出和神经肌肉传递。这种调节似乎依赖于Ia和/或Ib传入反馈。
