The University of Queensland, Centre for Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, Brisbane, Qld 4072, Australia.
Gait Posture. 2011 Apr;33(4):588-93. doi: 10.1016/j.gaitpost.2011.01.014. Epub 2011 Mar 5.
External perturbation of the trunk via sudden loading and unloading is an established method to study control of spinal stability and postural equilibrium. As differential control of the deep and superficial lumbar multifidus occurs during predictable sagittal loading, we hypothesized that the deep and superficial components of the thoracic paraspinal muscles would also be differentially active during loading and unloading of the trunk. Variation in sagittal mobility between regions of the thorax and previous data of differences in control of the thoracic paraspinal muscles between regions in other tasks supported a hypothesis that there would be region-specific differences in responses to loading and unloading. This study used fine-wire electrodes to record electromyographic (EMG) activity from the right deep (multifidus/rotatores) and superficial (longissimus) muscles at T5, T8, and T11 in ten healthy subjects during predictable and unpredictable sudden loading and unloading of the trunk. EMG amplitude was calculated during 10 ms epochs for 50 ms before the onset of trunk perturbation and 150 ms after the perturbation. Contrary to our hypotheses, deep and superficial thoracic paraspinal muscles were similarly active (loading: p=0.470; unloading: p=0.137) and similarly affected by the degree of predictability at all levels. Thus, deep and superficial thoracic paraspinal muscles are recruited en bloc during sagittal plane trunk perturbations. This contrasts previous findings of differential control between the deep and superficial thoracic paraspinal muscles during rotational tasks, and provides evidence that discrete control of thoracic paraspinal muscle fascicles is specific to the direction of forces applied to the trunk.
通过突然加载和卸载来对外周躯干进行干扰是研究脊柱稳定性和姿势平衡控制的一种既定方法。由于在可预测的矢状面加载过程中深、浅层腰椎多裂肌会出现差异控制，我们假设在躯干的加载和卸载过程中，胸段脊柱旁肌的深、浅层成分也会呈现差异激活。胸段不同区域矢状面活动度的变化以及其他任务中胸段脊柱旁肌控制方面的区域差异数据支持了这样一种假设，即存在针对加载和卸载的区域特异性反应差异。本研究使用细金属丝电极记录了 10 名健康受试者在可预测和不可预测的躯干突然加载和卸载过程中 T5、T8 和 T11 处右侧深层（多裂肌/回旋肌）和浅层（最长肌）肌肉的肌电图（EMG）活动。在躯干扰动开始前的 50 毫秒和扰动后的 150 毫秒内，计算 10 毫秒时窗的 EMG 幅度。与我们的假设相反，深、浅层胸段脊柱旁肌的活动（加载：p=0.470；卸载：p=0.137）和对各节段可预测性的影响相似。因此，在矢状面躯干扰动期间，深、浅层胸段脊柱旁肌被整块募集。这与之前在旋转任务中深、浅层胸段脊柱旁肌的差异控制发现形成对比，并提供了证据表明，对胸段脊柱旁肌肌束的离散控制是针对施加到躯干的力的方向特异性的。
