McKenzie D K, Gandevia S C
Department of Clinical Neurophysiology, Prince Henry Hospital, Sydney, Australia.
Respir Physiol. 1991 Apr;84(1):49-60. doi: 10.1016/0034-5687(91)90018-e.
This study was designed to compare the recovery from fatigue of human inspiratory and limb muscles using repeated maximal static contractions. Series of 18 maximal contractions of 10 sec duration were performed with a duty cycle of 50% for maximal inspiratory efforts (against a shutter at FRC), and with duty cycles of 5%, 10%, 20% and 50% for the elbow flexors in repeated studies on 6 subjects. The peak inspiratory pressure at the end of the series declined to 86.7% +/- 5.3% (mean +/- S.D.) of its initial value: maximal force of the elbow flexors declined to 83.5% +/- 7.0% (5% duty cycle), 80.0% +/- 5.5% (10% duty cycle), 70.0% +/- 9.3% (20% duty cycle), and 66.4% +/- 8.0% (50% duty cycle). Thus, the elbow flexors required approximately a 10-fold reduction in duty cycle to maintain over a series of contractions a force generating capacity comparable to that of the diaphragm. A small degree of 'central' fatigue developed progressively during all series of contractions but did not correlate with duty cycle. Fatigue-induced changes in twitch contraction properties varied with changes in duty cycle. Our major conclusions are that the human diaphragm has a marked capacity to recover from fatigue and that this may have been underestimated in previous studies from this and other laboratories.
本研究旨在通过重复最大静态收缩来比较人类吸气肌和肢体肌肉从疲劳中恢复的情况。对6名受试者进行了重复研究，其中最大吸气努力（在功能残气量时对抗挡板）进行了18次持续10秒的最大收缩，占空比为50%；肘部屈肌进行了18次最大收缩，持续时间为10秒，占空比分别为5%、10%、20%和50%。系列收缩结束时的最大吸气压力降至其初始值的86.7%±5.3%（平均值±标准差）；肘部屈肌的最大力量降至83.5%±7.0%（5%占空比）、80.0%±5.5%（10%占空比）、70.0%±9.3%（20%占空比）和66.4%±8.0%（50%占空比）。因此，肘部屈肌需要将占空比降低约10倍，才能在一系列收缩过程中保持与膈肌相当的力量产生能力。在所有系列收缩过程中，逐渐出现了轻度的“中枢”疲劳，但与占空比无关。疲劳引起的抽搐收缩特性变化随占空比变化而不同。我们的主要结论是，人类膈肌具有从疲劳中显著恢复的能力，而在本实验室和其他实验室之前的研究中，这一点可能被低估了。
