Lumbar loading during lifting: a comparative study of three measurement techniques

Low back loading during occupational lifting is thought to be an important causative factor in the development of low back pain. In order to regulate spinal loading in the workplace, it is necessary to measure it accurately. Various methods have been developed to do this, but each has its own limita tions, and none can be considered a "gold standard". The purpose of the cur rent study was to compare the results of three contrasting techniques in or der to gain insight into possible sources of error to which each is suscept ible. The three techniques were a linked segment model (LSM), an electromyo graphic (EMG)-based model, and a neural network (NN) that used both EMG and inertial sensing techniques. All three techniques were applied simultaneou sly to calculate spinal loading when eight volunteers performed a total of eight lifts in a laboratory setting. Averaged results showed that, in compa rison with the LSM, the EMG technique calculated a 25.5 +/- 33.4% higher pe ak torque and the NN technique a 17.3 +/- 10.5% lower peak torque. Differen ces between the techniques varied with lifting speed and method of lifting, and could be attributed to differences in anthropometric assumptions, anta gonistic muscle activity, damping of transient force peaks by body tissues, and, specific to the NN, underestimation of trunk flexion. The results of the current study urge to reconsider the validity of other models by indepe ndent comparisons. (C) 2001 Elsevier Science Ltd. All rights reserved.