Perceived exertion and discomfort versus work height with a pistol-shaped screwdriver

Seven vertical locations were rated after 36 subjects drove 25 No. 6 sheet metal screws into 18-gauge perforated sheet metal (hole size of 0.28 cm) with an air-powered pistol-shaped screwdriver at each location. The seven vertical heights ranged from 38 to 191 cm. Subjects rated each level using three psychophysical scales and were asked to imagine that they were assembly line workers required to drive screws at that work location using that particular tool for 8 hr. The three scales were the Borg 10-point ratio rating scale and two visual analogue scales. All subjects, regardless of anthropometry (5th percentile females to 95th percentile males), preferred driving screws between 114 and 139 cm. At the highest level of 191 cm, the shortest subjects disliked the level twice as much as the taller subjects. The three psychophysical scales were found to be comparable in sensitivity and use, although most subjects preferred the Borg rating scale. Future research and limitations of the current study are discussed.