FURTHER-STUDIES OF PSYCHOPHYSICALLY DETERMINED MAXIMUM ACCEPTABLE WEIGHTS AND FORCES

The effects of lifting boxes without handles, pulling long distances, carrying different size boxes, combining three handling tasks, and lif ting with extended horizontal reach were studied using a psychophysica l methodology. Six male industrial workers performed 42 variations of lifting, lowering, pushing, pulling, and carrying tasks. Lifting boxes without handles produced consistent decreases (median, 16%) in maximu m acceptable weights when compared with lifting boxes with handles. Li fting with extended horizontal reach (approximately 48 cm) produced co nsistent decreases (median, 48%) in maximum acceptable weights when co mpared with lifting close to the body (approximately 17 cm). No signif icant heart rate or oxygen consumption differences occurred in either of these variables. No significant differences in maximum acceptable w eight of carry were observed among box sizes; however, the maximum acc eptable force of pulling was lower for longer (15.2 m) pulling tasks. The maximum acceptable weight for combination tasks was similar to tha t of the limiting component.