Repetitive flexion of the lumbar spine during labour may have an impact on the development of low back pain, but current evidence is sparse. This study focuses on the effect of palletising on the lumbar spine's passive mechanics (flexion characteristics). As other passive structures begin to creep from long-term loading, changes in lumbar passive flexion characteristics have been hypothesised. The lumbar spine's passive flexion characteristics were investigated in 22 volunteers before and after palletising. For comparison, measurements were performed also during relaxed upright standing and while palletising with breaks for exercise. Measurement of passive flexion characteristics was done by a custom-made machine, and posture of the lumbar spine was captured by a kinematographic device. The torque acting within the body on lumbar level L4/5 was analysed. To exclude active forces by lumbar muscles during measurements, lumbar muscle activation was monitored by surface electromyography. Lumbar spine passive stiffness increased significantly (almost 50%) due to palletising. After relaxed standing and palletising with exercise breaks, this change could not be generally verified. The increased stiffness of passive structures of the lumbar spine provoked by palletising over half an hour suggests a degree of tissue fatigue. Even though it is unclear which passive structures change their passive mechanics and how this happens, this highlights the importance of break management during repetitive flexion of the lumbar spine.

分娩过程中腰椎反复屈曲可能会影响下腰痛的发生，但目前的证据很少。这项研究的重点是码垛对腰椎被动力学的影响（屈曲特性）。随着其他被动结构开始从长期负荷中蠕变，人们已经假设腰部被动屈曲特性会发生变化。在码垛前后，对22名志愿者进行了腰椎被动屈曲特性的调查。为了进行比较，在放松的直立站立过程中以及在有休息时间进行运动的码垛期间也进行了测量。被动屈曲特性的测量是通过一台定制机器完成的，而腰椎的姿势则被一个运动学设备捕获。分析了腰椎水平L4 / 5在体内产生的扭矩。为了在测量过程中排除腰肌的作用力，通过表面肌电图监测腰肌的激活。由于码垛，腰椎被动刚度显着提高（近50％）。经过放松的站立和锻炼休息后的码垛，这种变化通常无法得到验证。半小时内通过码垛引起的腰椎被动结构的刚度增加表明组织疲劳程度。尽管尚不清楚哪些被动结构会改变其被动力学以及如何发生这种情况，但这突出了在腰椎反复屈曲过程中进行休息管理的重要性。通过表面肌电图监测腰肌活化。由于码垛，腰椎被动刚度显着提高（近50％）。在放松的站立姿势和锻炼休息的码垛之后，这种变化通常无法得到验证。半小时内通过码垛引起的腰椎被动结构的刚度增加表明组织疲劳程度。尽管尚不清楚哪些被动结构会改变其被动力学以及如何发生这种情况，但这突出了在腰椎反复屈曲过程中进行休息管理的重要性。通过表面肌电图监测腰肌活化。由于码垛，腰椎的被动刚度显着提高（近50％）。经过放松的站立和锻炼休息后的码垛，这种变化通常无法得到验证。半小时内通过码垛引起的腰椎被动结构的刚度增加表明组织疲劳程度。尽管尚不清楚哪些被动结构会改变其被动力学以及如何发生这种情况，但这突出了在腰椎反复屈曲过程中进行休息管理的重要性。半小时内通过码垛引起的腰椎被动结构的刚度增加表明组织疲劳程度。尽管尚不清楚哪些被动结构会改变其被动力学以及如何发生这种情况，但这突出了在腰椎反复屈曲过程中进行休息管理的重要性。半小时内通过码垛引起的腰椎被动结构的刚度增加表明组织疲劳程度。尽管尚不清楚哪些被动结构会改变其被动力学以及如何发生这种情况，但这突出了在腰椎反复屈曲过程中进行休息管理的重要性。