Cholewicki J, Simons A P, Radebold A
Biomechanics Research Laboratory, Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, P.O. Box 208071, 06520-8071, New Haven, CT, USA.
J Biomech. 2000 Nov;33(11):1377-85. doi: 10.1016/s0021-9290(00)00118-4.
Stability of the lumbar spine is an important factor in determining spinal response to sudden loading. Using two different methods, this study evaluated how various trunk load magnitudes and directions affect lumbar spine stability. The first method was a quick release procedure in which effective trunk stiffness and stability were calculated from trunk kinematic response to a resisted-force release. The second method combined trunk muscle EMG data with a biomechanical model to calculate lumbar spine stability. Twelve subjects were tested in trunk flexion, extension, and lateral bending under nine permutations of vertical and horizontal trunk loading. The vertical load values were set at 0, 20, and 40% of the subject's body weight (BW). The horizontal loads were 0, 10, and 20% of BW. Effective spine stability as obtained from quick release experimentation increased significantly (p<0.01) with increased vertical and horizontal loading. It ranged from 785 (S.D.=580) Nm/rad under no-load conditions to 2200 (S.D.=1015) Nm/rad when the maximum horizontal and vertical loads were applied to the trunk simultaneously. Stability of the lumbar spine achieved prior to force release and estimated from the biomechanical model explained approximately 50% of variance in the effective spine stability obtained from quick release trials in extension and lateral bending (0.53<R(2)<0.63). There was no such correlation in flexion trials. It was concluded that lumbar spine stability increased with increased trunk load magnitude to the extent that this load brought about an increase in trunk muscle activation. Indirectly, our data suggest that muscle reflex response to sudden loading can augment the lumbar spine stability level achieved immediately prior to the sudden loading event.
腰椎稳定性是决定脊柱对突然加载反应的一个重要因素。本研究采用两种不同方法，评估了不同躯干负荷大小和方向如何影响腰椎稳定性。第一种方法是快速释放程序，通过躯干对阻力释放的运动学反应计算有效躯干刚度和稳定性。第二种方法将躯干肌肉肌电图数据与生物力学模型相结合来计算腰椎稳定性。12名受试者在躯干前屈、后伸和侧屈状态下，接受垂直和水平躯干负荷的9种组合测试。垂直负荷值设定为受试者体重（BW）的0%、20%和40%。水平负荷为BW的0%、10%和20%。通过快速释放实验获得的有效脊柱稳定性随着垂直和水平负荷的增加而显著增加（p<0.01）。其范围从无负荷条件下的785（标准差=580）Nm/rad到同时对躯干施加最大水平和垂直负荷时的2200（标准差=1015）Nm/rad。在力释放前通过生物力学模型估计的腰椎稳定性解释了在伸展和侧屈快速释放试验中获得的有效脊柱稳定性约50%的方差（0.53<R²<0.63）。在前屈试验中没有这种相关性。研究得出结论，腰椎稳定性随着躯干负荷大小的增加而增加，前提是这种负荷能引起躯干肌肉激活增加。间接而言，我们的数据表明，肌肉对突然加载的反射反应可以提高在突然加载事件发生前立即达到的腰椎稳定性水平。
