Muscular effort in four keyboard designs

The paper is addressed to the issue of health and safety in data entry tasks. Its importance is in examining basic geometrical measures in the design of keyboards for optimal usage in data processing. Seven professional typists participated in the investigation, operating four different keyboard geometry's. The keyboards were characterized as flat, negative, Tony and apart designs. The study includes objective and subjective parameters to identify geometrical measures for postural comfort and muscular efforts. EMG recordings were analyzed to determine four muscles' effort. The study indicates that a negative slope design has a geometrical advantage over three other keyboards. EMG findings show that the effort of the Flexor muscle, while keying with a negative keyboard design, is less by 36% than the effort found using Tony design, and by 58% less than using an apart design (p < 0.05). Typing quality was 64% lower when using Tony design and 60% lower when using apart design compared to the negative design (p < 0.05). Relevance to industry: The growing problem of work-related hazards in the expanding population of computer users was the rationale for this study which addressed itself to the issue of design for safety and performance in keyboard operations. (C) 2000 Elsevier Science B.V.