External perturbation of the trunk in standing humans differentially activates components of the medial back muscles
External perturbation of the trunk in standing humans differentially activates components of the medial back muscles
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DOI：
10.1113/jphysiol.2002.024950
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发表时间：
2003-03-01
影响因子：
5.5
通讯作者：
Gandevia, SC
中科院分区：
文献类型：
--
作者：
Moseley, GL;Hodges, PW;Gandevia, SC
在手臂随意运动期间，内侧背部肌肉的活动程度不同。目前尚不清楚当躯干受到不可预测的干扰时，当最早的反应是由短潜伏期脊柱机制而不是自愿命令发起时，是否也会发生差异活动。为了评估这一点，在不可预测和自发的条件下，将一个重物放入站立受试者拿着的桶中（n = 7）。记录腰多裂肌的深层（Deep MF）、浅层（Sup MF）和外侧（Lat MF）、胸椎竖脊肌（ES）和肱二头肌的肌电图活动。由于不可预测的扰动，肌电图活动首先在肱二头肌中被发现，然后是胸椎 ES，随后在多裂肌的各部分中同步出现。在自发扰动期间，七名受试者中的六名受试者的深层 MF 中的背景肌电图增加了两到三倍，并且负载反应的潜伏期减少了。在 Sup MF 和 Lat MF 中，没有观察到背景肌电图的增加，并且加载响应的潜伏期增加。当躯干负载时，短潜伏期反射机制不会引起内侧背部肌肉的差异动作。然而，在自愿任务期间，中枢神经系统会产生“调谐反应”，其中涉及内侧腰部肌肉深层和浅层成分的离散活动，其方式根据肌肉成分的生物力学作用而变化。
During voluntary arm movements, the medial back muscles are differentially active. It is not known whether differential activity also occurs when the trunk is perturbed unpredictably, when the earliest responses are initiated by short-latency spinal mechanisms rather than voluntary commands. To assess this, in unpredictable and self-initiated conditions, a weight was dropped into a bucket that was held by the standing subject (n = 7). EMG activity was recorded from the deep (Deep MF), superficial (Sup MF) and lateral (Lat MF) lumbar multifidus, the thoracic erector spinae (ES) and the biceps brachii. With unpredictable perturbations, EMG activity was first noted in the biceps brachii, then the thoracic ES, followed synchronously in the components of the multifidus. During self-initiated perturbations, background EMG in the Deep MF increased two- to threefold, and the latency of the loading response decreased in six out of the seven subjects. In Sup MF and Lat MF, this increase in background EMG was not observed, and the latency of the loading response was increased. Short-latency reflex mechanisms do not cause differential action of the medial back muscles when the trunk is loaded. However, during voluntary tasks the central nervous system exerts a 'tuned response', which involves discrete activity in the deep and superficial components of the medial lumbar muscles in a way that varies according to the biomechanical action of the muscle component.