Fractional factorial analysis of lifting and carrying tasks on postural score to investigate the effect of contributing parameters and their interactions

This laboratory experiment examines the effect of four lifting and carrying task parameters: load weight; lifting frequency; vertical lifting distance; and obstructions en route and their interactions on the posture score measured using the rapid upper limb assessment (RULA) methodology. In this simulation study, four shop floor workers lifted weights in 27 different combinations of lifting parameters, in which three different levels of lifting frequencies, load weights, vertical lifting heights and obstructions en route were considered. The subjects did symmetric lifting for 30 minutes period. Analysis of variance result showed that other than obstructions en route, the remaining main effects were significantly related with posture score measured using RULA methodology. Also, the interaction between the load weight and frequency of lift were significant for some of the subjects. The worker stress level varies from individual to individual when looked at separately for four different subjects. The loads to be placed at shoulder height are most stressful and should be avoided as far as possible. The results for posture scores show that lifting load from the floor level with high frequency of lift is the most stressful task.