Cortical and segmental excitability during fatiguing contractions of the soleus muscle in humans.
Cortical and segmental excitability during fatiguing contractions of the soleus muscle in humans.
复制标题
人类比目鱼肌疲劳收缩期间的皮质和节段兴奋性。
DOI：
10.1016/j.clinph.2011.06.031
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Shields,RichardK
中科院分区：
文献类型：
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作者：
Iguchi,Masaki;Shields,RichardK
目的本研究的目的是检查比目鱼肌疲劳过程中皮质和节段兴奋性的变化。 方法十名健康年轻受试者在 9 个时期的 5 次收缩中进行 45 次跖屈最大随意收缩（MVC）（7 秒开/3 秒关）。在任务期间使用经颅磁刺激和 H 反射评估运动诱发电位 (MEP)。 结果扭矩和比目鱼肌肌电图活动在第一个时期均显示出最大的下降，随后在任务结束时逐渐但显着下降（~70% 疲劳前）。每个时期后休息时采样的 H 反射在第一个时期后下降至疲劳前的 66.6±18.3%，然后没有显示出进一步的变化。每个时期后 10% 疲劳前 MVC 的 MEP 逐渐增加（252.9±124.2% 疲劳前）。每个时期的第三次 MVC 中的 MEP 没有变化。 MVC 的静默期早期增加（疲劳前 109.0±9.2%），并且在任务期间没有进一步的变化。结论这些发现支持运动皮层在疲劳期间增加兴奋性，但伴随着抑制。意义这些发现与上肢肌肉相反，可能反映了姿势抗疲劳肌肉特有的独特反应。
OBJECTIVEThe aim of this study was to examine the cortical and segmental excitability changes during fatigue of the soleus muscle.METHODSTen healthy young subjects performed 45 plantar flexion maximal voluntary contractions (MVCs) (7-s on/3-s off) in 9 epochs of five contractions. Motor evoked potentials (MEPs) using transcranial magnetic stimulation and H-reflexes were assessed during the task.RESULTSThe torque and the soleus EMG activity both showed the greatest decline during the 1st epoch, followed by a gradual, but significant decrease by the end of the task (∼70% pre-fatigue). The H-reflex sampled at rest after each epoch decreased to 66.6±18.3% pre-fatigue after the first epoch, and then showed no further change. The MEP on 10% pre-fatigue MVC after each epoch increased progressively (252.9±124.2% pre-fatigue). There was no change in the MEPs on the 3rd MVC in each epoch. The silent period on the MVC increased (109.0±9.2% pre-fatigue) early with no further changes during the task.CONCLUSIONSThese findings support that the motor cortex increases excitability during fatigue, but with a concomitant inhibition.SIGNIFICANCEThese findings are in contrast to upper extremity muscles and may reflect a distinct response specific to postural, fatigue-resistant muscle.