Neural factors account for strength decrements observed after short-term muscle unloading
Neural factors account for strength decrements observed after short-term muscle unloading
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DOI：
10.1152/ajpregu.00386.2001
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发表时间：
2002-02-01
影响因子：
2.8
通讯作者：
Kraemer, WJ
中科院分区：
文献类型：
--
作者：
Deschenes, MR;Giles, JA;Kraemer, WJ
在延长的（4-6周）肌肉卸载期后观察到的强度下降与显著的萎缩相关。由于早期（最多2周）从抗阻运动中获得的力量与神经募集的改善有关，我们假设2周肌肉卸载[单侧下肢悬吊（ULLS）]导致的力量损失是由于受影响肌肉的神经激活受损。血液样本，肌肉活检标本，肌肉功能数据和肌电图（EMG）记录进行了分析之前和之后的肌肉卸载14天。卸载前后数据显示，膝关节伸肌和屈肌的峰值扭矩和总做功显著（P小于或等于0.05）降低。这与EMG活动减少相结合，但神经肌肉效率（总扭矩/EMG）没有变化。ULLS后抗肌肉疲劳能力增强。14天的干预未能改变肌肉样本的大小或纤维类型分布。然而，静息血浆皮质醇水平显着增加肌肉卸载后，表明内分泌环境有利于肌肉萎缩。我们的数据证实，2周后显示的肌肉功能的减少主要是由于神经，而不是收缩，干扰。
Strength decrements observed after extended (4-6 wk) periods of muscle unloading are associated with significant atrophy. Because early (up to 2 wk) strength gains from resistance exercise are related to improved neural recruitment, we hypothesized that the loss of strength resulting from 2 wk of muscle unloading [unilateral lower limb suspension (ULLS)] was due to impaired neural activation of the affected muscle. Blood samples, muscle biopsy specimens, muscle function data, and electromyography (EMG) recordings were analyzed before and after 14 days of muscle unloading. Pre- to postunloading data showed significant (P less than or equal to 0.05) decrements in peak torque and total work performed by knee extensors and flexors. This was coupled with decreased EMG activity, but no change in neuromuscular efficiency (total torque/EMG). Resistance to muscle fatigue was enhanced after ULLS. The 14-day intervention failed to alter the size or fiber type distribution of muscle samples. However, resting plasma cortisol levels were significantly increased after muscle unloading, suggesting an endocrine environment favorable to muscle atrophy. Our data confirm that the diminution in muscle function displayed after 2 wk of unloading is mainly due to neural, rather than contractile, disturbances.