Finger Muscle Activity during Use of Different Pointing Devices

Abstract

The purpose of this study was to compare surface and fine wire EMG amplitude measures from the extrinsic index finger muscles while subjects performed computer based pointing tasks with four different pointing devices. Fifteen subjects, without a history of upper extremity musculoskeletal disorders were recruited to this laboratory study. Fine wires were inserted into the extrinsic index finger movers and surface EMG electrodes were placed over the same muscles. Maximum voluntary contractions were performed for each muscle group. Subjects then performed two standardized pointing tasks, one involving repeated clicking of the mouse button and the other involving repeated dragging. The RMS EMG signals were filtered, normalized to MVC, and amplitude probability distribution functions at 10, 50 and 90% were calculated. Subjects also rated fatigue and discomfort associated with each devices and tasks. Summary measures of the EMG and subjective ratings will be evaluated using repeated measures analysis of variance for the two conditions and four devices.