Mechanisms of fatigue differ after low- and high-force fatiguing contractions in men and women
Mechanisms of fatigue differ after low- and high-force fatiguing contractions in men and women
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DOI：
10.1002/mus.20844
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发表时间：
2007-10-01
期刊：
影响因子：
3.4
通讯作者：
Hunter, Sandra K.
中科院分区：
文献类型：
--
作者：
Yoon, Tejin;Delap, Bonnie Schlinder;Hunter, Sandra K.
在男性和女性中，不同强度的疲劳收缩后自主驾驶失败的程度尚不清楚。本研究的目的是比较男性和女性在进行低强度和高强度肘部屈肌持续等长收缩时任务失败的时间和自愿激活。9名男性和9名女性分别以20%和80%的最大自主收缩力（MVC）进行等距收缩，直到任务失败。在20%的MVC任务中，男性比女性失败的时间要短，而在80%的MVC任务中则不然。在疲劳收缩结束时，男性和女性的自愿激活减少到相似的水平，但在80% MVC任务后减少的程度低于20% MVC任务后减少的程度。在任务失败时，两性的抽搐幅度都有相似的减少，在20%和80% MVC任务结束时也有相似的减少。平均动脉压变化率是低力持续收缩失效时间的主要预测因子。这些结果表明，在低力疲劳收缩中，女性比男性经历了更大的肌肉灌注，更少的周围疲劳，以及更长的任务失败时间。然而，无论男性还是女性，低力量的任务比高力量的收缩更容易引起中枢疲劳。因此，低强度、长时间的疲劳收缩可用于康复，以诱导中枢神经系统的显著疲劳，并可能使男性和女性的神经适应能力增强。
The magnitude of failure in voluntary drive after fatiguing contractions of different intensities in men and women is not known. The purpose of this study was to compare the time to task failure and voluntary activation of men and women for a sustained isometric contraction performed at a low and high intensity with the elbow flexor muscles. Nine men and nine women sustained an isometric contraction at 20% and 80% of maximal voluntary contraction (MVC) force until task failure during separate sessions. The men had a shorter time to failure than women for the 20% but not the 80% MVC task. Voluntary activation was reduced to similar levels for the men and women at the end of the fatiguing contractions but was reduced less after the 80% MVC task than the 20% MVC contraction. Twitch amplitude was reduced similarly at task failure for both sexes and to similar levels at termination of the 20% and 80% MVC tasks. The rate of change in mean arterial pressure was the main predictor of time to failure for the low-force sustained contraction. These results suggest that women experienced greater muscle perfusion, less peripheral fatigue, and a longer time to task failure than men during the low-force fatiguing contraction. However, the low-force task induced greater central fatigue than the high-force contraction for both men and women. Thus, low-force, long-duration fatiguing contractions can be used in rehabilitation to induce significant fatigue within the central nervous system and potentially greater neural adaptations in men and women.