Stabilizing function of trunk flexor-extensor muscles around a neutral spine posture
Stabilizing function of trunk flexor-extensor muscles around a neutral spine posture
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DOI：
10.1097/00007632-199710010-00003
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发表时间：
1997-10-01
期刊：
影响因子：
3
通讯作者：
Khachatryan, A
中科院分区：
文献类型：
--
作者：
Cholewicki, J;Panjabi, MM;Khachatryan, A
研究设计。这项研究考察了健康个体躯干屈肌和伸肌的共同激活情况。在腰椎机械稳定性的背景下对实验肌电数据和理论计算进行分析。为了测试一组与健康人有关的假设：1)躯干屈伸肌协同激活存在于中性脊柱姿势周围，2)当受试者负重时协同激活增加；3)协同激活为腰椎提供所需的机械稳定性。从理论上讲，躯干肌肉的拮抗性共激活对于为人体腰椎提供中性体位周围的机械稳定性是必要的。然而，没有实验证据支持这一假设。10名受试者执行缓慢的躯干屈伸任务，同时对右侧6块肌肉进行表面肌电监测：外斜肌、内斜肌、腹直肌、多裂肌、腰椎竖脊肌和胸椎竖脊肌。还进行了简单但真实的脊柱稳定性计算，并与实验结果进行了比较。肌电图仪检测到，中性脊柱姿势周围的平均拮抗性屈伸肌协同激活水平，在无外部负荷试验中为最大自主收缩的1.7+/-0.8%，在躯干增加32公斤质量的试验中为最大自愿收缩的2.9+/-1.4%。基于静态力矩平衡准则的倒立摆模型预测不存在拮抗共激活。基于机械稳定性标准的同一模型预测了零负荷下屈伸肌最大自愿收缩共激活的1.0%，以及质量为32公斤的最大自愿收缩的3.1%。稳定性模型也在脊柱被动刚度为零的情况下运行以模拟损伤。在此条件下，模型预测在无额外负荷和增加32 kg时，拮抗肌肉协同激活的最大自愿收缩分别为3.4%和5.5%。这项研究表明，在健康个体的中性脊柱姿势周围，存在躯干屈伸肌的拮抗性协同激活。这种协同激活随着躯干质量的增加而增加。使用生物力学模型，完全基于神经肌肉系统为腰椎提供机械稳定性的需要来解释协同激活。
Study Design. This study examined the coactivation of trunk flexor and extensor muscles in healthy individuals. The experimental electromyographic data and the theoretical calculations were analyzed in the context of mechanical stability of the lumbar spine.Objectives. To test a set of hypotheses pertaining to healthy individuals: 1) that the trunk flexor-extensor muscle coactivation is present around a neutral spine posture, 2) that the coactivation is increased when the subject carries a load; and 3) that the coactivation provides the needed mechanical stability to the lumbar spine.Summary of Background Data. Theoretically, antagonistic trunk muscle coactivation is necessary to provide mechanical stability to the human lumbar spine around its neutral posture. No experimental evidence exists, however, to support this hypothesis.Methods. Ten individuals executed slow trunk flexion-extension tasks, while six muscles on the right side were monitored with surface electromyography: external oblique, internal oblique, rectus abdominis, multifidus, lumbar erector spinae, and thoracic erector spinae. Simple, but realistic, calculations of spine stability also were performed and compared with experimental results.Results. Average antagonistic flexor-extensor muscle coactivation levels around the neutral spine posture as detected with electromyography were 1.7 +/- 0.8% of maximum voluntary contraction for no external load trials and 2.9 +/- 1.4% of maximum voluntary contraction for the trials with added 32-kg mass to the torso. The inverted pendulum model based on static moment equilibrium criteria predicted no antagonistic coactivation. The same model based on the mechanical stability criteria predicted 1.0% of maximum voluntary contraction coactivation of flexors and extensors with zero load and 3.1% of maximum voluntary contraction with a 32-kg mass. The stability model also was run with zero passive spine stiffness to simulate an injury. Under such conditions, the model predicted 3.4% and 5.5% of maximum voluntary contraction of antagonistic muscle coactivation for no extra load and the added 32 kg, respectively.Conclusions. This study demonstrated that antagonistic trunk flexor-extensor muscle coactivation was present around the neutral spine posture in healthy individuals. This coactivation increased with added mass to the torso. Using a biomechanical model, the coactivation was explained entirely on the basis of the need for the neuromuscular system to provide the mechanical stability to the lumbar spine.