Mechanisms of force failure during repetitive maximal efforts in a human upper airway muscle.
Mechanisms of force failure during repetitive maximal efforts in a human upper airway muscle.
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人类上呼吸道肌肉重复最大努力过程中力衰竭的机制。
DOI：
10.1002/mus.10167
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
Fregosi,RalphF
中科院分区：
文献类型：
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作者：
DelloRusso,Christiana;Khurana,Nilam;Rankin,Lucinda;Sullivan,Jenna;Fregosi,RalphF
上气道呼吸肌在调节气道阻力方面发挥着重要作用，但令人惊讶的是，人们对它们的收缩特性和耐力表现知之甚少。我们开发了一种技术，可以测量力和肌电图（EMG）的人鼻扩张肌（NDM）。通过测量NDM“张开”力和EMG活动来量化耐力表现，健康人类受试者进行10秒最大自主收缩（MVC），间隔10秒休息，直到力曲线下的面积下降到50%MVC（疲劳任务的时间限制，Tlim），在34.2 ± 3.1次收缩（685.0 ± 62.3秒）中达到。除Tlim外，EMG活动无变化，其平均值为测试前活动的78.7 ± 3.6%（P< 0.01）。M波振幅没有变化，表明神经肌肉传播没有受损。恢复后10分钟内，MVC力增加至试验前水平的80%，但抽搐力未能恢复，表明低频疲劳。这些数据表明，神经系统兴奋肌肉的失败最多只能解释间歇性疲劳任务期间NDM力损失的一小部分，并且只能解释Tlim。因此，在这项任务中，大多数力的失败是由于肌肉纤维内的机制受损。© 2002 Wiley Periodicals，Inc.肌肉神经26：94-100，2002
The upper airway respiratory muscles play an important role in the regulation of airway resistance, but surprisingly little is known about their contractile properties and endurance performance. We developed a technique that allows measurement of force and the electromyogram (EMG) of human nasal dilator muscles (NDMs). Endurance performance was quantified by measuring NDM “flaring” force and EMG activity as healthy human subjects performed 10 s maximal voluntary contractions (MVCs), separated by 10 s rest, until the area under the force curve fell to 50% MVC (the time limit of the fatigue task, Tlim), which was reached in 34.2 ± 3.1 contractions (685.0 ± 62.3 s). EMG activity was unchanged except at Tlim, where it averaged 78.7 ± 3.6% of pretest activity (P< 0.01). M‐wave amplitude did not change, suggesting that neuromuscular propagation was not impaired. MVC force increased to 80% of the pretest level within 10 min of recovery but twitch force failed to recover, suggesting low‐frequency fatigue. The data suggest that a failure of the nervous system to excite muscle could explain at most only a small fraction of the NDM force loss during an intermittent fatigue task, and then only at Tlim. Thus, the majority of the force failure during this task is due to impairment of mechanisms that reside within the muscle fibers. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 94–100, 2002