Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
School of Physical & Health Education, Nipissing University, North Bay, ON, Canada.
J Biomech. 2014 Jan 22;47(2):491-6. doi: 10.1016/j.jbiomech.2013.10.055. Epub 2013 Nov 9.
Lumbar spine stability has been extensively researched due to its necessity to facilitate load-bearing human movements and prevent structural injury. The nature of certain human movement tasks are such that they are not equivalent in levels of task-stability (i.e. the stability of the external environment). The goal of the current study was to compare the effects of dynamic lift instability, administered through both the load and base of support, on the dynamic stability (maximal Lyapunov exponents) and stiffness (EMG-driven model) of the lumbar spine during repeated sagittal lifts. Fifteen healthy males performed 23 repetitive lifts with varying conditions of instability at the loading and support interfaces. An increase in spine rotational stiffness occurred during unstable support scenarios resulting in an observed increase in mean and maximum Euclidean norm spine rotational stiffness (p=0.0011). Significant stiffening effects were observed in unstable support conditions about all lumbar spine axes with the exception of lateral bend. Relative to a stable control lifting trial, the addition of both an unstable load as well as an unstable support did not result in a significant change in the local dynamic stability of the lumbar spine (p=0.5592). The results suggest that local dynamic stability of the lumbar spine represents a conserved measure actively controlled, at least in part, by trunk muscle stiffening effects. It is evident therefore that local dynamic stability of the lumbar spine can be modulated effectively within a young-healthy population; however this may not be the case in a patient population.
由于腰椎在承载人体运动和防止结构损伤方面的必要性，其稳定性已得到广泛研究。某些人类运动任务的性质使得它们在任务稳定性（即外部环境的稳定性）水平上并不等同。本研究的目的是比较通过负载和支撑基础施加的动态提升不稳定性对重复矢状提升过程中腰椎的动态稳定性（最大 Lyapunov 指数）和刚度（EMG 驱动模型）的影响。15 名健康男性在负载和支撑界面的不同不稳定性条件下进行了 23 次重复提升。在不稳定的支撑情况下，脊柱旋转刚度增加，导致平均和最大欧几里得范数脊柱旋转刚度观察到增加（p=0.0011）。在所有腰椎轴上都观察到不稳定支撑条件下的明显僵硬效应，除了侧屈。与稳定控制提升试验相比，在不稳定的负载以及不稳定的支撑的情况下，腰椎的局部动态稳定性没有显著变化（p=0.5592）。结果表明，腰椎的局部动态稳定性是一种保守的测量指标，至少在一定程度上受到躯干肌肉僵硬效应的主动控制。因此，很明显，年轻健康人群中可以有效地调节腰椎的局部动态稳定性；然而，在患者人群中情况可能并非如此。
