Cortical and spinal mechanisms of task failure of sustained submaximal fatiguing contractions.
Cortical and spinal mechanisms of task failure of sustained submaximal fatiguing contractions.
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DOI：
10.1371/journal.pone.0093284
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Clark BC
中科院分区：
文献类型：
--
作者：
Williams PS;Hoffman RL;Clark BC
在这篇论文和随后的配套文件中，结果提出，共同寻求描绘的贡献，脊髓上的电路在确定持续次最大收缩的任务失败（TTF）的时间。本研究的目的是比较在两种不同疲劳任务的执行过程中同时进行的脊髓上和脊髓兴奋性的调整，这两种疲劳任务具有相同的机械要求，但TTF不同（即，力匹配和位置匹配任务）。在单独的访问中，10名健康志愿者在手肘屈肌任务失败的情况下以最大力量的15%执行力匹配或位置匹配任务。单脉冲经颅磁刺激（TMS），成对脉冲TMS，成对的皮质颈髓刺激，臂丛神经电刺激，在6个刺激序列在基线和每2-3分钟在整个疲劳任务的性能。与预期相反，力匹配任务TTF（17.5±7.9 min）比位置匹配任务（26.9±15.11 min; p<0.01）短42%;然而，两种任务引起的肌肉疲劳量相同（p = 0.59）。 在神经生理学结果变量随时间的变化总量或变化率方面没有任务特异性差异（p>0.05）。因此，失败发生在运动神经元兴奋性出现类似的平均下降（p<0.02，ES = 0.35-0.52），同时皮质脊髓兴奋性指标出现类似的平均增加（p<0.03，ES = 0.30-0.41）之后。 此外，皮质内抑制量减少（p<0.03，ES = 0.32），皮质内易化量（p>0.10）和运动皮质上游兴奋指数保持不变（p>0.40）。 总之，这些结果表明，随着疲劳在任务失败之前发展，观察到的与脊髓兴奋性降低相关的皮质脊髓兴奋性增加是皮质内抑制降低与皮质内易化和上游兴奋性恒定水平的组合的结果，皮质内抑制降低与皮质内易化和上游兴奋性恒定水平的组合最终未能向运动皮质提供下行驱动所需的输入以克服脊髓阻力，从而导致任务失败。
In this and the subsequent companion paper, results are presented that collectively seek to delineate the contribution that supraspinal circuits have in determining the time to task failure (TTF) of sustained submaximal contractions. The purpose of this study was to compare adjustments in supraspinal and spinal excitability taken concurrently throughout the performance of two different fatigue tasks with identical mechanical demands but different TTF (i.e., force-matching and position-matching tasks). On separate visits, ten healthy volunteers performed the force-matching or position-matching task at 15% of maximum strength with the elbow flexors to task failure. Single-pulse transcranial magnetic stimulation (TMS), paired-pulse TMS, paired cortico-cervicomedullary stimulation, and brachial plexus electrical stimulation were delivered in a 6-stimuli sequence at baseline and every 2–3 minutes throughout fatigue-task performance. Contrary to expectations, the force-matching task TTF was 42% shorter (17.5±7.9 min) than the position-matching task (26.9±15.11 min; p<0.01); however, both tasks caused the same amount of muscle fatigue (p = 0.59). There were no task-specific differences for the total amount or rate of change in the neurophysiologic outcome variables over time (p>0.05). Therefore, failure occurred after a similar mean decline in motorneuron excitability developed (p<0.02, ES = 0.35–0.52) coupled with a similar mean increase in measures of corticospinal excitability (p<0.03, ES = 0.30–0.41). Additionally, the amount of intracortical inhibition decreased (p<0.03, ES = 0.32) and the amount of intracortical facilitation (p>0.10) and an index of upstream excitation of the motor cortex remained constant (p>0.40). Together, these results suggest that as fatigue develops prior to task failure, the increase in corticospinal excitability observed in relationship to the decrease in spinal excitability results from a combination of decreasing intracortical inhibition with constant levels of intracortical facilitation and upstream excitability that together eventually fail to provide the input to the motor cortex necessary for descending drive to overcome the spinal cord resistance, thereby contributing to task failure.
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影响因子：
2.5
作者：
Di Lazzaro, V.;Pilato, F.;Rothwell, J. C.
通讯作者：
Rothwell, J. C.
影响因子：
3.4
作者：
BIGLANDRITCHIE, B;WOODS, JJ
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DOI：
10.1111/j.1600-0838.2010.01148.x
发表时间：
2011-12-01
影响因子：
4.1
作者：
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DOI：
10.1249/00005768-198205000-00012
发表时间：
1982-01-01
期刊：
MEDICINE AND SCIENCE IN SPORTS AND EXERCISE
影响因子：
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作者：
BORG, GAV
通讯作者：
BORG, GAV
影响因子：
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作者：
Chen, R;Lozano, AM;Ashby, P
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