The effect on forearm and shoulder muscle activity in using different thickness computer keyboards

• Main Authors: Luen-Zhi Chang, 張倫智
• Other Authors: Han-Ming Chen
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/47619624097830897878

碩士 === 臺灣大學 === 機械工程學研究所 === 95 === Several ergonomics researches had devoted to treat the effect of the shape of a keyboard on working posture and upper extremity muscle activity. There was no study associated with computer keyboard thickness from our survey literatures. The purpose of this study was to examine the effect of computer keyboard thickness on forearm muscle activity and wrist posture. In this experiment 28 subjects participated voluntarily and performed the same copy typing task while using four different thickness keyboards separately. During typing, the muscle activity of the bilateral extensor carpi ulnaris (ECU), extensor digitorum communis (ED) and upper trapezius (Trap) muscles, and the wrist postures were recorded by surface electrodes and twin axis electrogoniometers respectively. The keyboards T0 and NB were simulated as zero height keyboards and notebook keyboards separately. The use of the keyboards T0 and NB resulted in the lowest mean ulnar deviation of 11.59° and lowest mean wrist extension of 17.55° respectively. Moreover, the thicker keyboard used, the more wrist deviation from the neutral position was. The tendencies of the ECU and ED were similar to that of the wrist extension. From the above, using the zero thickness keyboard or the notebook keyboard would decrease the risks of musculoskeletal symptoms of upper extremity and carpal tunnel syndrome. The results may make recommendations for users to pick out and purchase keyboards.