The Friction Force Mouse-Pad and the Forearm Muscles Efforts

The objective of the article is to evaluate the impact of the friction force mouse-pad in the contraction level of the forearm muscles M. extensor carpi ulnaris, M. extensor digitorum and M. extensor carpi radialis longus. A standard protocol of mouse movements was performed involving horizontal, vertical and diagonal mouse displacements drag-anddrop type. The operators were instructed to execute the protocol with their normal working speed. The movements protocol were performed by each subject (n=17) with three selected pairs mouse-pad, classified as low, medium and high friction force pairs. The mean time to execute the protocol with each mouse was ~138 s. Mean values of ~13%MVE (Maximum Voluntary Electromyography signal), ~17%MVE and ~10%MVE were found in the M. extensor digitorum, M. extensor carpi ulnaris and in the M. extensor carpi radialis longus respectively when performing the movements’ protocol. A 8.1% increase in %MVE was observed in the M. extensor digitorum and a 9.4% increase in %MVE was observed in the M. extensor carpi ulnaris when the high friction force pair was operated, relatively to the low friction force pair (p<0.05). The main conclusions of this study is that operating a high friction force mouse-pad (with 79 g of static longitudinal friction force measured with a compression force of 100 g on the mouse) may increase the risk to symptoms or disorders in the wrist, particularly during work with drawing applications, due to an increase in the forearm muscles contraction levels.