Abstract
The rating of acceptable load (RAL) attained with a standard test (RALst) and a work-simulating test (RALw) for postal parcel sorting was related to anthropometric, muscle strength, and spinal mobility characteristics of 18 male sorters. The subjects comprised a subsample of 103 experienced male sorters who carried out the RAL tests at postal sorting centres. The dynamic hand-grip endurance correlated significantly (p=0·036) to the RALst results. Correspondingly, there was a significant correlation ( p=0·044) between the ratio of maximal isometric strength of trunk extension to body weight and the RALw. The dynamic hand-grip endurance predicted 26% of the variation in the RALst; in the RALw the maximal isometric strength of trunk flexion to body weight ratio predicted 24%. The subjects who rated heavier weights for RALst, tended to have a better trunk mobility. The dynamic endurance of hand-grip muscles, trunk strength, and spinal flexibility seemed to be the most powerful predictors for the psychophysically assessed ‘acceptable loads’ in experienced workers performing manual materials handling tasks.