Upperlimb EMG and Discomfort for Forearm Torques Combined with Horizontal Forces

Abstract

The first part of the study examined maximum forearm torque in both the supination and pronation directions at three forearm joint rotation angles. EMG data were also collected during the maximal exertions. The second part of the study involved subjects exerting intermittent isometric torques at 10% and 20% of MVC in both torque directions, at three forearm angles. These conditions were each tested while simultaneously applying a pushing, pulling and no pushing or pulling horizontal force. The results show that supination torque was strongest and that maximum torque in both directions were significantly affected by forearm joint angle. Very high levels of muscular activity in the forearm flexors and extensors during the exertions point to a direct link between the torques and injury. Discomfort scores from the intermittent exercises revealed significant main effects for force level, forearm angle and the application of a horizontal force simultaneous to applying torques, while direction of torque was only significant in interactions.