PROCEEDINGS of the HUMAN FACTORS SOCIETY 35th ANNUAL MEETlNG-1991 FINGERTIP FORCES WHILE USING THREE DIFFERENT KEYBOARDS

The relationship of chronic musculoskeletal disorders, such as carpal tunnel syndrome and wrist tendinitis, to prolonged alphanumeric keyboard use is controversial. Known risk-factors for these disorders, such as repetition of task, forceful exertions, awkward joint postures, direct mechanical pressure, and prolonged constrained posture, may be applicable to keyboard use. In this study fingertip forces were measured for 10 typists using three alphanumeric keyboards that differed only in their key force and displacement characteristics. While subjects typed, peak fingertip force was collected for each keystroke using strain gauge load cells. The mean peak fingertip forces applied by all subjects for all keys for the three keyboards were 193 gm, 182 gm and 220 gm; significantly different means. The 18 % reduction in fingertip force in the second keyboard compared with the third is attributed to a higher minimum force of activation and a higher force at total key travel in the third keyboard. This study indicates that keyboard key force-displacement characteristics can be altered to reduce the fingertip forces applied by typists and theoretically this may reduce the risk of developing chronic musculoskeletal disorders