Herrmann Christine M, Madigan Michael L, Davidson Bradley S, Granata Kevin P
Department of Mechanical Engineering, Virginia Polytechnic Institute and State University (0238) Blacksburg, VA 24061, United States.
J Electromyogr Kinesiol. 2006 Dec;16(6):637-41. doi: 10.1016/j.jelekin.2005.11.004. Epub 2006 Jan 6.
Low back disorders are a frequent medical problem. Altered neuromuscular control of the spine has been associated with low back pain, and may contribute to its occurrence. The purpose of this study was to investigate the effect of lumbar extensor fatigue on reflex delay and amplitude in the paraspinal muscles. Ten healthy males (20-22 years of age) were subjected to an anteriorly-directed perturbation applied at the inferior margin of the scapulae while standing quietly before and after a lumbar extensor fatiguing protocol. The fatiguing protocol consisted of multiple sets of back extensions and intermittent isometric maximum voluntary contraction on a Roman chair for 14 min until 60% of unfatigued lumbar extensor MVC was reached. Reflexes were recorded from the paraspinal muscles at the level of L4. Results indicated the mean reflex delay was 60+/-18 ms and was not affected by fatigue (p=0.278). Reflex amplitude increased 36+/-32% with fatigue (p=0.017). The increase in reflex amplitude may reflect an attempt to compensate for losses in muscle force capacity with fatigue in order to maintain sufficient spinal stability. However, additional studies are necessary to investigate the mechanisms of this fatigue-related change in paraspinal reflex.
下背部疾病是常见的医学问题。脊柱神经肌肉控制的改变与下背部疼痛有关，可能导致其发生。本研究的目的是调查腰椎伸肌疲劳对椎旁肌反射延迟和幅度的影响。10名健康男性（20 - 22岁）在进行腰椎伸肌疲劳方案前后安静站立时，在肩胛骨下缘施加向前的扰动。疲劳方案包括在罗马椅上进行多组背部伸展和间歇性等长最大自主收缩，持续14分钟，直到达到未疲劳腰椎伸肌最大随意收缩力的60%。在L4水平记录椎旁肌的反射。结果表明，平均反射延迟为60±18毫秒，不受疲劳影响（p = 0.278）。反射幅度随疲劳增加36±32%（p = 0.017）。反射幅度的增加可能反映了一种试图通过疲劳来补偿肌肉力量能力损失以维持足够脊柱稳定性的尝试。然而，需要进一步的研究来调查这种与疲劳相关的椎旁反射变化的机制。
