Comparison of the Prediction Models for the L5/S1 Compressive Forces under Varying Asymmetric Lifting Conditions

Abstract

In this study, comparisons were made among three representative methods for predicting compressive forces on the lumbosacral disc: LP-based model, double LP-based model and EMG-assisted model. Two subjects simulated lifting tasks that were frequently performed in the refractories industry in Korea, in which vertical distance, frontal plane horizontal distance, and weight of load were varied. To calculate the L5/S1 compressive forces, EMG signals from six trunk muscles were measured and postural data were recorded using the Motion Analysis System. The EMG-assisted model was shown to reflect well all three factors considered here. On the other hand, the compressive forces of the two LP-based models were significantly affected only by weight of load. Furthermore, relatively low correlation was observed between the compressive force of the EMG-assisted model and the 1991 NIOSH lifting index(LI), while highly positive correlation was observed between that of the two LP-based models and LI.