PURPOSE This study aimed at investigating the effects of different body positions and axial loads on spinal stiffness to better understand spinal stabilisation mechanisms. METHODS The posterior-to-anterior lumbar and thoracic spinal stiffness of 100 young healthy adults (mean age 23 years; 50 females) were measured in three test situations: prone, standing and standing while carrying a load equal to 50% of the subject's body weight. Each test situation comprised three trials. RESULTS Spinal stiffness in all test situations showed good reliability. Repeated measures analysis of covariance showed significantly higher spinal stiffness in standing than in the prone position [F(1/1694) = 433.630, p < 0.001]. However, spinal stiffness was significantly lower when standing while carrying a load of 50% of the body weight than when standing without additional load [F(1/1494) = 754.358, p < 0.001]. CONCLUSION This study showed that spinal lumbar and thoracic stiffness increases when body position is changed from prone to standing. Additional axial load of 50% of the subject's body weight results in reduced spinal stiffness during standing. These slides can be retrieved under Electronic Supplementary Material.

中文翻译：

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身体位置和轴向负荷对健康年轻人的脊柱僵硬的影响。

目的本研究旨在研究不同的身体位置和轴向负荷对脊柱僵硬的影响，以更好地了解脊柱稳定机制。方法在三种测试情况下，对100名年轻健康成年人（平均年龄23岁； 50名女性）的腰椎前后位置和胸椎刚度进行了测量：俯卧，站立和站立时负重等于受试者身体的50％重量。每个测试情况包括三个试验。结果在所有测试情况下，脊柱僵硬度均显示出良好的可靠性。重复测量的协方差分析显示站立时的脊椎刚度明显高于俯卧位[F（1/1694）= 433.630，p <0.001]。然而，站立时承受的重量为体重的50％，其站立时的脊椎刚度显着低于不承受额外负荷时的站立[F（1/1494）= 754.358，p <0.001]。结论这项研究表明，当身体位置从俯卧改变为站立时，脊柱腰椎和胸腔的僵硬度会增加。受测者体重的50％的额外轴向负荷会导致站立时脊柱僵硬程度降低。这些幻灯片可以在电子补充材料下找到。