Maximal Acceptable Torques of Highly Repetitive Screw Driving, Wrist Flexion and Extension with a Pinch grip, Ulnar Deviation, and Handgrip Tasks for Seven Hour Workdays for Male Industrial Workers

摘要

The purpose of the study was to quantify maximum acceptable torques of six tasks performed on separatedays but within the context of the same experiment. The six tasks were screw driving clockwise with a 40mm handle and a 39 mm yoke handle; flexion and extension with a pinch grip; ulnar deviation with apower grip (similar to knife cutting), and a handgrip task (similar to a pliers task). A psychophysicalmethodology was used in which the subject adjusted the resistance of the task, and the experimentercontrolled all other variables. Sixteen male industrial workers performed the six tasks at repetition rates of15 and 25 motions per minute. Subjects performed the tasks for 7 hours per day, 5 days per week, for 12days. The subjects were instructed to work as if they were on an incentive basis, getting paid for theamount of work they performed. Symptoms were recorded by the subjects during the last 5 minutes ofeach hour. The results revealed that mean maximum acceptable torques ranged from 1.15 Nm to 1.88 Nmfor screw driving, 2.26 Nm to 3.71 Nm for pinch flexion and extension, 3.88 Nm to 4.07 Nm for ulnardeviation, and 11.47 Nm to 13.98 Nm for the handgrip task. These values represented 15% to 35%(median of 23%) of maximum isometric torques depending on the repetition rate and the task.