Abstract
An electromyographic investigation was conducted of finger and wrist muscle activity during typing. Examination of the data revealed substantial activity of the extrinsic extensor, a muscle which is ignored in many existing biomechanical finger models. This paper describes activity of the extensor muscle during typing, in absolute terms and relative to activity of the extrinsic flexors. Amplitude probability distribution analyses demonstrated that static extensor activity exceeded 5% MVC for all subjects. Two subjects exhibited pronounced patterns of coactivity in the extrinsic extensor and flexor muscles. Biomechanical modeling efforts demonstrated similar force contributions from the extrinsic extensors and flexors. Based on these results, neglect of finger extensor activity would result in underestimation of finger joint loading.
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