La flexion répétitive de la colonne lombaire pendant le travail peut avoir un impact sur le développement de la lombalgie, mais les preuves actuelles sont rares. Cette étude se concentre sur l’effet de la palettisation sur la mécanique passive de la colonne lombaire (caractéristiques de flexion).
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.