Biomechanical differences between expert and novice workers in a manual material handling task

Abstract

The objective was to verify whether the methods were safer and more efficient when used by expert handlers than by novice handlers. Altogether, 15 expert and 15 novice handlers were recruited. Their task was to transfer four boxes from a conveyor to a hand trolley. Different characteristics of the load and lifting heights were modified to achieve a larger variety of methods by the participants. The results show that the net moments at the L5/S1 joint were not significantly different (p > 0.05) for the two groups. However, compared with the novices, the experts bent their lumbar region less (experts 54° (SD 11°); novices 66° (SD 15°)) but bent their knees more (experts approx. 72° (SD approx. 30°); novices approx. 53° (SD approx. 33°), which brought them closer to the box. The handler's posture therefore seems to be a major aspect that should be paid specific attention, mainly when there is maximum back loading.

Statement of Relevance: The findings of this research will be useful for improving manual material handling training programmes. Most biomechanical research is based on novice workers and adding information about the approach used by expert handlers in performing their tasks will help provide new avenues for reducing the risk of injury caused by this demanding physical task.

Keywords:

• ergonomic intervention
• expert
• low back load
• lifting
• manual material handling

Acknowledgements

The present research project was funded by the Robert-Sauvé Occupational Health and Safety Research Institute (IRSST) of Quebec. Special thanks go to the expert and novice subjects and the industries that participated in this project.

Notes

†Other members of the IRSST MMH research group: Marie St-Vincent, Iuliana Nastasia, Sophie Bellefeuille, Maud Gonella, Denis Gagnon (Sherbrooke University).