Human Factors Criteria for the Design and Acquisition of ... - FAA

Keyboards June 20049.4 Wrist/PalmrestThe goals of a wrist/palm rest are to reduce shouldermuscle loads and promote a neutral wrist posture withoutnegatively affecting productivity or introducing localizedcontact stress. Wrist/palm rests can help users avoidlocalized contact stress that may be caused by the edge of aworkstation or keyboard. Wrist/palm rests are thought topromote more neutral wrist posture by reducing wristextension. However, for some users, wrist/palm restsincrease wrist discomfort, and they can potentially increasecarpal tunnel pressure or cause awkward wrist positions.Although the term “wrist rest” is used as an umbrella termin the general populace, properly designed wrist rests areintended to support the palm or heel of the hand rather thanthe actual wrist. [Source: Grandjean et al., 1983; Hagglund &Jacobs, 1996; Horie, Hargens & Rempel, 1993; Hunting et al., 1981;Parsons, 1991; Paul & Menon, 1994, Smith, Karsh, Conway, Cohen,James, Morgan, Sanders & Zehel, 1998]9.4.1 Shape of wrist rest. When keyboards have integratedor attachable wrist rests or supports, the wrist rest orsupport should be matched to the width, height, and shapeof the front edge of the keyboard. [Source: Paul & Menon,1994]Exhibit 9.4.1 Wrist restAdditional Information. Broad flat wrist rests arepreferable to narrow curved shapes because contouredwrist rests can cause more wrist deviation than flat pads.[Source: Paul & Menon, 1994]9-8