BackgroundThe recovery of neurophysiological parameters at various time intervals following fatiguing exercise has been investigated previously. However, the repetition of neuromuscular assessments during the recovery period may have interfered with the true corticomotor excitability responses. In this experiment, fatiguing contractions were combined with a single post-fatigue assessment at varying time points. Ten participants undertook 5 bouts of 60-s maximal voluntary contractions (MVC) of the elbow flexors, separated by 20 min. Before and after each 60-s fatiguing exercise (FAT), participants performed a series of 6-s contractions at 100, 75 and 50% of their MVC during which transcranial magnetic, transmastoid electrical and brachial plexus electrical stimuli were used to elicit motor evoked potentials (MEP), cervicomedullary motor evoked potentials (CMEP) and compound muscle action potentials (Mmax) in the biceps brachii muscle, respectively. Post-FAT measurements were randomly performed 0, 15, 30, 60, or 120 s after each FAT.ResultsMVC force declined to 65.1 ± 13.1% of baseline following FAT and then recovered to 82.7 ± 10.2% after 60 s. The MEP·Mmax−1 ratio recorded at MVC increased to 151.1 ± 45.8% and then returned to baseline within 60 s. The supraspinal excitability (MEP·CMEP−1) measured at MVC increased to 198.2 ± 47.2% and fully recovered after 30 s. The duration of post-MEP silent period recorded at MVC elongated by 23.4 ± 10.6% during FAT (all P < 0.05) but fully recovered after 15 s.ConclusionsThe current study represents the first accurate description of the time course and pattern of recovery for supraspinal and spinal excitability and inhibition following a short maximal fatiguing exercise in upper limb.

中文翻译：

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肘屈肌皮质运动反应的短期恢复

背景先前已经研究了疲劳运动后不同时间间隔神经生理学参数的恢复。然而，在恢复期间重复进行神经肌肉评估可能会干扰真正的皮质运动兴奋性反应。在这个实验中，疲劳收缩与不同时间点的单一疲劳后评估相结合。10 名参与者进行了 5 次 60 秒的肘屈肌最大自主收缩 (MVC)，间隔 20 分钟。在每次 60 秒疲劳运动 (FAT) 之前和之后，参与者在其 MVC 的 100%、75% 和 50% 进行了一系列 6 秒收缩，在此期间使用经颅磁、经乳突电和臂丛神经电刺激来引发运动诱发电位（MEP），分别测量肱二头肌中的颈髓运动诱发电位 (CMEP) 和复合肌肉动作电位 (Mmax)。在每个 FAT 后 0、15、30、60 或 120 秒随机进行 FAT 后测量。结果 FAT 后 MVC 力下降至基线的 65.1 ± 13.1%，然后在 60 秒后恢复至 82.7 ± 10.2%。在 MVC 记录的 MEP·Mmax-1 比率增加到 151.1 ± 45.8%，然后在 60 秒内恢复到基线。在 MVC 下测量的脊髓上兴奋性 (MEP·CMEP-1) 增加到 198.2 ± 47.2% 并在 30 秒后完全恢复。在 MVC 记录的 MEP 后静默期的持续时间在 FAT 期间延长了 23.4 ± 10.6%（所有 P < 0.05），但在 15 秒后完全恢复。