The loads on the lumbar spine during work at an assembly line. The risks for fatigue injuries of vertebral bodies.

This study was performed in an attempt to determine the total spinal compressive load during assembly line work to find a possible association with the many complaints of back pain. A flexion analyzer was used to register trunk movements, and analysis of postures and lifted weights was done from video recordings. The load on the spine at the L3 level was calculated through a biomechanical model, meant for analysis of static, sagittally symmetric postures and lifting tasks. Maximum lift tests were performed before and after a full work day. The peak load on the L3-L4 level when lifting corresponded to an average 22% of the load at the lift test. The mean load during a work cycle was 818 N. It was concluded that the many complaints of back pain could not be attributed to high peak loads, repetitivity of the lifts, or large load doses. Monotony, stress, and low job satisfaction are more likely factors of greater importance.