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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICESPublic Health Service
Centers for Disease Control and PreventionNational Institute for Occupational Safety and Health
To date, there is little information to assistpeople interested in purchasing alternativekeyboards. While the scientific evidenceabout whether alternative keyboards preventmusculoskeletal disorders is inconclusive atthis time, this document provides basicinformation about common alternativekeyboard designs and their effects on workposture.
Why Redesign the Keyboard?
When typing, holding the hands and wrists in aneutral work posture--where the hands areextended straight without significant bending atthe wrist-- is thought to reduce the risk ofmusculoskeletal problems. Computer userssometimes use awkward or non-neutral workpostures when working on the traditionalkeyboard. They rotate their forearms so that
their palms are facing the keyboard (A), andthey often bend their hands outward (B) andupward (C & D). Sometimes, workers also holdtheir elbows slightly away from their bodies (E)while keying, particularly when the keyboardsurface is too high. Alternative keyboards canhelp keep wrists straight as shown on thefollowing pages.
Alternative keyboards use different designsto attempt to change the users posture. Thefollowing are some of the more commondesigns.
Split keyboards are designed to straighten thewrist. This can be done in two ways: byincreasing the distance between the right andleft sides of the keyboard or by rotating eachhalf of the keyboard so that each half isaligned with the forearm. Some alternativekeyboards combine these two methods.
Split and Rotated Keyboard with Wrist Rest
Whats Different AboutAlternative Keyboards?
On tented keyboards, the two keyboard halvesare tilted up like a tent. This feature is a varia-tion of the split keyboard and reduces therotation of the forearms.
Built-in wrist or palm rests
Built-in wrist or palm rests help prevent bend-ing the hands up by providing support thatstraightens the wrists. It should be noted thatquestions do remain about the usefulness ofwrist or palm rests. For example, it is unclearwhether they increase pressure on the wrists,relieve loads on shoulder and upper backmuscles, or interfere with typing.
Split and Tented Keyboard
Some alternative keyboard designs haveattempted to fit the different lengths of thefingers by curving the rows of keys or byplacing the keys in concave wells. This isbelieved to allow the fingers to work in a morerelaxed posture (see illustrations on next page).
Whats Different AboutAlternative Keyboards? (Continued)
Keyboard withNegative Slope
Adjustable negative slope
Keyboards with a negative slope also helpprevent bending the hand too far up by allowingthe user to raise the front edge of the keyboard,or to slope the keyboard backward, thusstraightening the wrist.
Concave Well Keyboard
Alternative keyboards have been shown topromote neutral wrist posture. Yet, availableresearch does not provide conclusiveevidence that alternative keyboards reducethe risk of discomfort or injury.
Thus, further research is needed beforespecific keyboard features can berecommended with great confidence.
Do Alternative KeyboardsPrevent Injuries?
What if I Want to Use anAlternative Keyboard?
If alternative keyboards are to be used inthe workplace, the following suggestionsmay be helpful in making purchasingdecisions.
Determine whether the keyboard is
compatible with existing hardware andsoftware and whether the keyboard canaccommodate other input devices, suchas trackballs and mice.
Assess how the keyboard will fit withthe workstation. Some alternativekeyboards are extra wide, long, or highand may not fit on standard keyboardtrays. Such keyboards may also preventthe tray from retracting under the worksurface. Additionally, some alternativekeyboards, particularly tented versions,must be placed on surfaces that arelower than those required for theconventional keyboard to achieveproper working posture.
Evaluate whether the keyboard willaffect the performance of the user.Some alternative keyboard designs andadjustments make it difficult to see the
keys. This is particularly important forusers who rely on key visibility, such ashunt and peck typists. Also, checkwhether the job requires use of thenumeric keypad and specialized keys,because some alternative keyboardseliminate or reconfigure these keys.
Allow users to try a keyboard on a trialbasis before buying it. It would seemreasonable to try the keyboard for atleast one to two weeks, since studiesshow that this amount of time isnecessary to adapt to alternativekeyboards.
Alternative keyboards are like otheroffice equipment, furniture oraccessories. Preferences will vary andone type will not fit everyone or everytype of task. Allow users to try anumber of different alternativekeyboards before making decisionsabout which ones to buy. If a user wantsto retain his or her conventionalkeyboard, respect that decision.
What if I Want to Use anAlternative Keyboard? (Continued)
Expect frustration until users becomefamiliar with the new keyboards.Frustration frequently results fromdiminished productivity as workers getused to new equipment.
Involve a specialist in thedecision-making process. Thisspecialist should have both knowledgeand experience in office ergonomics. Ifa computer user has discomfort ormusculoskeletal symptoms, a healthprofessional should also be involved inmaking the decision to purchase analternative keyboard.
Integrate a new alternative keyboardinto the work process carefully. Makesure that users are trained in theappropriate use of the product, sincemany alternative keyboards can beused incorrectly. If the keyboard isadjustable, encourage users to changethe adjustments gradually from theconventional (flat) configuration.
A keyboard is only one part of a computerworkstation setup that may influence comfort.Other important factors include: workstationand chair adjustability; placement ofequipment, accessories, and work materials;lighting; and the design and organization ofwork tasks.
Because computer work is highly repetitive andpromotes static postures, it can causediscomfort over long periods of time. It isimportant to break up long sessions of keyboardwork with frequent rest breaks or with othertasks that require movements different fromthose used to type or operate the mouse.
What Can Be Done to PreventMusculoskeletal Injuries?
Keep in mind that it is essential to examine theentire work environment to determine allpossible causes of discomfort. In other words, itis unlikely that changing only one workplaceelement, such as a keyboard, will eliminate alldiscomfort and disorders.
In addition, each workplace should have acomprehensive ergonomics program in place toprotect all workers.
Call NIOSH at
or visit the NIOSH Homepage at
to receive: A bibliography on alternative keyboard research. Information on implementing an ergonomics
program (request Elements of ErgonomicsPrograms: A Primer Based on WorkplaceEvaluations of Musculoskeletal DisordersDHHS (NIOSH) Publication No. 97-117).
More information on workplace safety andhealth issues.
For additional information,contact NIOSH at:
Fax number: (513) 533-8573
orvisit the NIOSH Home Page on the world Wide Web at
DHHS (NIOSH) Publication No. 97-148
The National Institute for Occupational Safetyand Health (NIOSH) is the Federal agencyresponsible for conducting research andmaking recommendations for the preventionof work-related disease and injury. TheInstitute is part of the Centers for DiseaseControl and Prevention.
PurposeWhy Redesign the Keyboard?Whats Different About Alternative Keyboards?Do Alternative Keyboards Prevent Injuries?What if I Want to Use an Alternative Keyboard?What Can Be Done to Prevent Musculoskeletal Injuries?