Hodges Paul, van den Hoorn Wolbert, Dawson Anna, Cholewicki Jacek
School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane Qld 4072, Australia.
J Biomech. 2009 Jan 5;42(1):61-6. doi: 10.1016/j.jbiomech.2008.10.001. Epub 2008 Dec 4.
Exercise is one of the few effective treatments for LBP. Although exercise is often based on the premise of reduced spinal stiffness, trunk muscle adaptation may increase stiffness. This study developed and validated a method to assess trunk stiffness and damping, and tested these parameters in 14 people with recurring LBP and 17 pain-free individuals. Effective trunk stiffness, mass and damping were estimated with the trunk modeled as a linear second-order system following trunk perturbation. Equal weights (12-15% body weight) were attached to the front and back of the trunk via pulleys such that the trunk could move freely and no muscle activity was required to hold the weights. The trunk was perturbed by the unexpected release of one of the weights. Trunk kinematics and cable force were used to estimate system properties. Reliability was assessed in 10 subjects. Trunk stiffness was greater in recurrent LBP patients (forward perturbation only), but damping was lower (both directions) than healthy controls. Estimates were reliable and validated by accurately estimated mass. Contrary to clinical belief, trunk stiffness was increased, not reduced, in recurrent LBP, most likely due to augmented trunk muscle activity and changes in reflex control of trunk muscles. Although increased stiffness may aid in the protection of spinal structures, this may have long-term consequences for spinal health and LBP recurrence due to compromised trunk dynamics (decreased damping).
运动是治疗下背痛（LBP）少数有效的方法之一。尽管运动通常基于降低脊柱僵硬度的前提，但躯干肌肉适应性可能会增加僵硬度。本研究开发并验证了一种评估躯干僵硬度和阻尼的方法，并在14名复发性下背痛患者和17名无疼痛个体中测试了这些参数。通过将躯干建模为线性二阶系统，在躯干受到扰动后估计有效躯干僵硬度、质量和阻尼。通过滑轮在躯干前后附着相等重量（体重的12 - 15%），使躯干能够自由移动，且无需肌肉活动来支撑重量。通过意外释放其中一个重量来扰动躯干。利用躯干运动学和绳索力来估计系统特性。在10名受试者中评估了可靠性。复发性下背痛患者的躯干僵硬度更大（仅向前扰动时），但阻尼低于健康对照组（两个方向均如此）。估计值可靠，且通过准确估计的质量得到验证。与临床认知相反，复发性下背痛患者的躯干僵硬度增加而非降低，这很可能是由于躯干肌肉活动增强以及躯干肌肉反射控制的改变。尽管增加的僵硬度可能有助于保护脊柱结构，但由于躯干动力学受损（阻尼降低），这可能会对脊柱健康和下背痛复发产生长期影响。
