A Study of the Interaction between Load and Coupling during Lifting

Publisher Website
Google Scholar
Abstract
The National Institute for Occupational Safety and Health (NIOSH) has increased the applicability of its lifting equation to a wider range of jobs by relaxing some of the simplifying assumptions of the original equation. Specifically, NIOSH has added an asymmetry factor and a coupling factor in the revised lifting equation. Two of the remaining simplifications, however, are that (1) interactions between terms are not considered and (2) the biomechanical analysis still utilizes a static modelling approach in its calculations. The purpose of the present research was to investigate the interaction between coupling and load magnitude under dynamic lifting conditions. Subjects lifted a box under various combinations of coupling and load. The dependent variables in this study were the peak external moment about the lumbosacral joint (as calculated by a dynamic biomechanical model) and the peak vertical ground reaction forces. The results show that at low levels of load there was little difference in peak torque across the different coupling conditions. However, when loads greater than 13.5 kg were combined with poor coupling, there was a fundamental change in the dynamics of the lifting motion. The results of this study indicate that the role of coupling under dynamic lifting conditions has both a perceptual and biomechanical effect which should be considered when designing manual materials handling tasks.

This publication has 6 references indexed in Scilit: