EMG of Forearm Muscles in Torqueing Task with Respect to Grip Force, Stroke Rotation and Frequency

Abstract

The objective of present study was to investigate the effect of grip force, stroke rotation and frequency on EMG activities of forearm muscles. Twenty seven participants volunteered in this study. Participants performed repetitive upper limb exertions at three levels of grip force (50N, 70N & 90N), three levels of stroke rotation (30°, 45° and 60°) and three levels of frequency (10 exertions/min, 15 exertions/min & 20 exertions/min). The study was divided into three groups based on grip force therefore a 3x3 factorial design was used. Task duration was 5 minutes for each combination. Multivariate analysis of variance (MANOVA) was used and found normalised EMG of muscles FCR, FCU and ECR was significantly affected by grip force; and frequency was significant on normalised EMG of muscles FCR, ECR and ECU. Also, slope of median frequency (relative indication of muscle fatigue) was significantly affected by grip force on muscles FCR, ECU and stroke rotation on muscle FCU. Both two-way interaction (grip force & frequency) and (grip force & stroke rotation) were found significant on muscle ECU. Threeway interaction effect was found significant only on muscle FCU. Results found that extensor muscles were more fatigued in torqueing and gripping task. Although findings of present study revealed that if occupational task designers taken care of factors considered in this study, working environment could be more comfortable and productive.