Fatigue induced changes in phasic muscle activation patterns for fast elbow flexion movements
Fatigue induced changes in phasic muscle activation patterns for fast elbow flexion movements
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DOI：
10.1007/s00221-001-0904-9
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发表时间：
2002-01-01
影响因子：
2
通讯作者：
Gottlieb, GL
中科院分区：
文献类型：
--
作者：
Corcos, DM;Jiang, HY;Gottlieb, GL
本研究探讨了肌肉疲劳如何影响单自由度肘关节屈曲运动及其相关的阶段性肌肉激活模式。在实验开始时测量最大非疲劳自愿等长肘屈肌和伸肌关节扭矩。然后，受试者尽可能快地在两个距离内进行肘关节屈曲运动，并以故意较慢的速度在较长距离内进行运动。这个速度，已经接近了疲劳状态下的极限速度。然后，受试者进行了20个持续等长屈曲收缩25秒的持续时间与5秒的休息在50%的最大非疲劳随意力的疲劳协议。经过一段时间的恢复，他们重复了这些动作。疲劳方案成功地诱导肌肉疲劳，证据是等长最大关节扭矩降低超过20%。重复运动的肌肉扭矩和速度峰值较低。我们的主要发现是疲劳肌肉激活的阶段性模式的时间变化。通过EMG信号的质心测量，激动剂爆发的持续时间增加，拮抗剂肌肉的时间延迟。我们的结论是，这些变化作为部分的，但不完整的，集中驱动的补偿疲劳引起的肌肉功能的变化。另一个意外的发现是，当使用10分钟的恢复时间时，疲劳对运动表现的影响是多么小，这段时间足够长，可以让肌肉膜传导速度恢复正常。这就提出了关于人类疲劳机制的经典实验室研究的行为意义的问题。
The present study investigated how muscle fatigue influences single degree-of-freedom elbow flexion movements and their associated patterns of phasic muscle activation. Maximal unfatigued voluntary isometric elbow flexor and extensor joint torque was measured at the beginning of the experiment. Subjects then performed elbow flexion movements over two distances as fast as possible, and movements over the longer distance at an intentionally slower speed. The slower speed was close to what would become the maximal speed in the fatigued state. Subjects then performed a fatiguing protocol of 20 sustained isometric flexion contractions of 25 s duration with 5 s rest at 50% maximal unfatigued voluntary force. After a recovery period they repeated the movements. The fatigue protocol was successful in inducing muscle fatigue, the evidence being decreased isometric maximal joint torque of over 20%. Fatigued movements had lower peak muscle torque and speed. Our principal finding was of changes in the timing of the phasic patterns of fatigued muscle activation. There was an increase in the duration of the agonist burst and a delay in the timing of the antagonist muscle as measured by the centroid of the EMG signals. We conclude that these changes serve as partial but incomplete, centrally driven compensation for fatigue induced changes in muscle function. An additional, unexpected finding was how small an effect fatigue had on movement performance when using a recovery time of 10 min that is long enough to allow muscle membrane conduction velocity to return to normal. This raises questions concerning the behavioral significance of classical laboratory studies of human fatigue mechanisms.