Keyboards June 2004Additional in<strong>for</strong>mation. Proper keyboard design canminimize <strong>the</strong> potential <strong>for</strong> cumulative trauma disorder;however, some research implies that even with properkeyboard design, cumulative trauma disorders can occur iftoo much time is spent typing, particularly if typing at ahigh rate <strong>and</strong>/or under time pressure. There is no definitiveamount specifying exactly what constitutes safe keyboardusage, although some research has found increases inrepetitive stress injuries with 4-6 hours <strong>of</strong> typing a day or6-8 hours <strong>of</strong> numeric pad use <strong>and</strong> with more than 20 hours<strong>of</strong> typing a week. Keyboard use <strong>for</strong> less than 8 hours aweek is not associated with an increased risk <strong>of</strong> carpaltunnel syndrome. [Source: Andersen, Thomsen, Oergaard, Lassen,Br<strong>and</strong>t, Vilstrup, Kryger & Mikkelsen, 2003; Gerr, Marcus, &Monteilh, 2004; Moore, Garg, Roberts, & Root, 1997; Palmer, Cooper,Walker-Bone, Syddall & Coggon, 2001]9.2.2 Pace <strong>of</strong> keyboarding work. Users should be allowedto pace <strong>the</strong>mselves when per<strong>for</strong>ming extensivekeyboarding tasks. [Source: Gerard, Armstrong, Martin &Rempel, 2002]Additional in<strong>for</strong>mation. Forcing users to keep a particularpace leads to increased muscle activity <strong>and</strong> fatigue. [Source:Gerard et al., 2002]9.2.3 Limits <strong>of</strong> keyboard work duration. At minimum,users should be given a 30-second break from typing every15-20 minutes <strong>and</strong> a 3-minute break from typing everyhour. [Source: Galinsky, Swanson, Sauter, Hurrell & Schleifer, 2000;Henning, Jacques, Kissel, Sullivan & Alteras-Webb, 1997; Kopardekar& Mithal, 1994; McLean, Tingley, Scott & Rickards, 2001]Additional in<strong>for</strong>mation. Research shows that productivitymay increase <strong>and</strong> errors decrease when breaks are taken.For example, Kopardekar & Mithal (1994) showed thatusers committed 80% more errors when working <strong>for</strong> 2hours without a break than if <strong>the</strong>y were given a 5-minutebreak <strong>for</strong> every 30 minutes <strong>of</strong> work. Risk <strong>for</strong> discom<strong>for</strong>t<strong>and</strong> cumulative trauma disorder increases after 1 hour <strong>of</strong>continuous typing. In general, short, frequent breaks inwork are more desirable than long, infrequent breaks.However, breaks needed depend on work intensity, speed,<strong>and</strong> repetition <strong>of</strong> tasks. [Source: Henning et al., 1997; Kopardekar& Mithal, 1994; Matias et al., 1998]9-3
Keyboards June 20049.2.4 Activity during breaks. During breaks fromkeyboarding activity, users should per<strong>for</strong>m stretching<strong>and</strong>/or exercise activities ra<strong>the</strong>r than sitting <strong>and</strong> resting.[Source: Henning et al., 1997; Lee, Swanson, Sauter, Wickstrom,Waikar & Mangum, 1992]9.2.5 Indication <strong>of</strong> break times. Users should be in<strong>for</strong>medthat it is time to take a break in a way that does notinterrupt or disrupt <strong>the</strong>ir task. [Source: McLean et al, 2001]Additional in<strong>for</strong>mation. S<strong>of</strong>tware programs are availablethat indicate rest-break intervals based on <strong>the</strong> intensity <strong>of</strong><strong>the</strong> work being per<strong>for</strong>med. Breaks are more effective whenscheduled than when allowing users discretion over whento take <strong>the</strong> breaks. [Source: McLean et al, 2001]9.3 Workstationcharacteristics <strong>for</strong>keyboard use9.3.1 Location <strong>for</strong> frequent keyboarding tasks. The mainkeyboard <strong>for</strong> frequent keyboarding tasks should be locateddirectly in front <strong>of</strong> <strong>the</strong> user so as to allow <strong>the</strong> user to adopt<strong>and</strong> maintain <strong>the</strong> following body angles:a. Elbows at an angle <strong>of</strong> greater than 90 degrees.Exhibit 9.3.1.a Elbow angle9-4
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- Page 31 and 32: Keyboards June 20049.6.1 Toggle key
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- Page 35 and 36: Keyboards June 20049.7 Numerickeypa
- Page 37 and 38: Keyboards June 20049.8 Keydimension
- Page 39 and 40: Keyboards June 20049.9 Key labeling
- Page 41 and 42: Keyboards June 20049.10 Keyactivati
- Page 43 and 44: Keyboards June 20049.10.7 Key repea
- Page 45 and 46: Keyboards June 2004Exhibit 9.12.b A
- Page 47 and 48: Keyboards June 2004Exhibit 9.12.g V
- Page 49 and 50: Keyboards June 20049.12.1 Split key
- Page 51 and 52: Keyboards June 20049.14 Membranekey
- Page 53 and 54: Keyboards June 20049.15.7 Colored k
- Page 55 and 56: Keyboards June 2004GlossaryABC keyb
- Page 57 and 58: Keyboards June 2004Homing timeKey f
- Page 59 and 60: Keyboards June 2004ReferencesAaras,
- Page 61 and 62: Keyboards June 2004Conrad, R., & Lo
- Page 63 and 64: Keyboards June 2004Henning, R., Jac
- Page 65 and 66: Keyboards June 2004Marteniuk, R. G.
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Keyboards June 2004Rempel, D., Bach
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Keyboards June 2004Swanson, N. G.,
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