Exploring the Addition of Torso Flexion to the LIFFT Analysis Tool

Abstract

The Lifting Fatigue Failure Tool (LiFFT) is an ergonomic assessment tool based on fatigue failure theory that uses the lower back load moment to evaluate the risk associated with multi-task jobs involving manual lifting. The current LiFFT tool does not account for the moment associated with flexing the lifter's torso. This study explores the incorporation of torso flexion into the LiFFT model while maintaining the relative simplicity of the original LiFFT tool. Automotive manufacturing workers (n=607) performing various tasks were included in the study. Non-manual material handling (MMH) tasks with no MMH load moment were considered "zero" risk. The moment associated with trunk flexion was considered if a worker flexed at the torso during non-MMH assembly tasks. The torso moment from bending was computed using the "average" worker height and weight for the data set used in this study. The proposed model yielded higher odds ratios than the original model.