Bed rest induces neural and contractile adaptations in triceps surae.
Bed rest induces neural and contractile adaptations in triceps surae.
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卧床休息会诱导小腿三头肌的神经和收缩适应。
DOI：
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发表时间：
1995
影响因子：
4.1
通讯作者：
J. Duchateau
中科院分区：
文献类型：
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作者：
J. Duchateau
由于强烈的直立性头痛，一名受试者卧床5wk，检查了小腿三头肌的机电适应性。研究了自发性收缩和电诱导收缩时，小腿三头肌产生的扭矩和慢比目鱼肌(SOL)和快外侧腓肠肌(LG)的肌电活动。卧床休息导致最大自主收缩(MVC)扭矩下降46%。这种力量的丧失与中枢激活的33%和估计的肌肉力量产生能力的19%的缺陷有关。在MVC过程中，两个肌肉的肌电活动均有下降，但LG(-51%)比SOL(-32%)的下降幅度更大。SOL组最大M波(Mmax)波幅下降幅度(-28%)大于LG组(-12%)。卧床休息后，电诱导收缩的最大张力发展速率(dt/dt)降低了31%，自主收缩的最大张力发展速率(dt/dt)降低了24%。虽然在60-S持续的MVC中，肌肉的疲劳性不受卧床时间的影响，但这两种肌肉的相对贡献与对照组不同。这些结果表明，SOL的肌肉适应性更显著，而LG的神经适应性更显着。此外，神经改变在2周内几乎完全恢复，而收缩改变至少需要5倍的时间才能恢复到控制值。
The electromechanical adaptations of the triceps surae muscle were examined in one subject confined to bed for 5 wk due to strong orthostatic headaches. The torque produced by the triceps surae and the electromyographic (EMG) activities of the slow soleus (Sol) and fast lateral gastrocnemius (LG) were studied in response to voluntary and electrically induced contractions. Bed rest caused a 46% decrease in the maximal voluntary contraction (MVC) torque. This loss of strength was associated with a deficit of 33% in central activation and 19% in the estimated muscle force-generating capacity. The EMG activity during MVC was found to be reduced in both muscles, but to a greater extent in the LG (-51%) than in the Sol (-32%). The decrease in amplitude of the maximal M wave (Mmax) recorded in response to supramaximal electrical stimulation was greater in Sol (-28%) than in LG (-12%). After bed rest, the twitch time to peak torque was slightly prolonged (+9%) and the maximal rate of tension development (dT/dt) was reduced by 31% in electrically induced and 24% in voluntary contractions. Although muscle fatigability during a 60-s sustained MVC was not affected by the bed rest period, the relative contributions of the two muscles differed from control. These results indicate that muscular adaptations were more prominent in Sol while neural adaptations were more significant in LG. Furthermore, the neural changes almost completely recovered within 2 wk, whereas the contractile alterations required at least 5 times longer to return to the control values.