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Alternative Keyboards

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service Centers for Disease Control and Prevention National Institute for Occupational Safety and Health

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Purpose
To date, there is little information to assist people interested in purchasing alternative keyboards. While the scientific evidence about whether alternativekeyboards prevent musculoskeletal disorders is inconclusive at this time, this document provides basic information about common alternative keyboard designs and their effects on work posture.

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Why Redesign the Keyboard?

When typing, holding the hands and wrists in a neutral work posture--where the hands are extended straight without significant bending at the wrist-- isthought to reduce the risk of musculoskeletal problems. Computer users sometimes use awkward or non-neutral work postures when working on the traditional keyboard. They rotate their forearms so that

A

B

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their palms are facing the keyboard (A), and they often bend their hands outward (B) and upward (C & D). Sometimes, workers also hold their elbows slightly away from theirbodies (E) while keying, particularly when the keyboard surface is too high. Alternative keyboards can help keep wrists straight as shown on the following pages. C

D

E

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What’s Different About Alternative Keyboards?
Alternative keyboards use different designs to attempt to change the user’s posture. The following are some of the more common designs.

Split keyboardsSplit keyboards are designed to straighten the wrist. This can be done in two ways: by increasing the distance between the right and left sides of the keyboard or by rotating each half of the keyboard so that each half is aligned with the forearm. Some alternative keyboards combine these two methods.

Split and Rotated Keyboard with Wrist Rest

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Tented keyboards On tentedkeyboards, the two keyboard halves are tilted up like a tent. This feature is a variation of the split keyboard and reduces the rotation of the forearms.

Split and Tented Keyboard Built-in wrist or palm rests Built-in wrist or palm rests help prevent bending the hands up by providing support that straightens the wrists. It should be noted that questions do remain about the usefulness of wristor palm rests. For example, it is unclear whether they increase pressure on the wrists, relieve loads on shoulder and upper back muscles, or interfere with typing.

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What’s Different About Alternative Keyboards? (Continued)
Adjustable negative slope Keyboards with a negative slope also help prevent bending the hand too far up by allowing the user to raise the front edge ofthe keyboard, or to slope the keyboard backward, thus straightening the wrist.

Conventional Keyboard

Keyboard with Negative Slope

Key position Some alternative keyboard designs have attempted to “fit” the different lengths of the fingers by curving the rows of keys or by placing the keys in concave wells. This is believed to allow the fingers to work in a more relaxed posture (seeillustrations on next page).

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Straight Keyboard

Concave Well Keyboard

Curved Keyboard

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Do Alternative Keyboards Prevent Injuries?
Alternative keyboards have been shown to promote neutral wrist posture. Yet, available research does not provide conclusive evidence that alternative keyboards reduce the risk of discomfort or injury. Thus, furtherresearch is needed before specific keyboard features can be recommended with great confidence.

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What if I Want to Use an Alternative Keyboard?
If alternative keyboards are to be used in the workplace, the following suggestions may be helpful in making purchasing decisions. Determine whether the keyboard is compatible with existing hardware and software and whether the keyboard...