How to determine the need for an alternative keyboard:
If you feel tension in your forearms when you rotate your arms to type on a flat keyboard, then a keyboard that is sloped or tented is best for you. Examples of tented or sloped keyboards: Goldtouch, MS Natural.
If you notice that your wrists must bend inward while you are typing on a straight keyboard, you should use a split keyboard. A split keyboard has the keys split down the middle and angled somewhat toward the left and right sides of the body. A split keyboard is generally more comfortable for people with large torsos, broad shoulders, or a wide elbow angle. To test yourself for a wide elbow angle, with relaxed shoulders and elbows hanging by your sides, hold thumbs up with wrists even with your elbows. Rotate thumbs inward toward each other. If your elbows move away from your body, consider a split keyboard. If your elbows remain next to your body, a straight, conventional keyboard is probably fine.
If you tend to place a conventional keyboard at an angle, check your elbow angle (see item above). You may benefit from a split keyboard.
People with large hands will be more comfortable with keys farther apart or large keys.
A mini-keyboard is great for someone who needs reduced reach to the mouse on the right and does not need a split keyboard. It is also useful when space is limited.
A mini-keyboard is most important for petite and slender individuals, people with small hands and best for children.
When choosing a keyboard, consider the location of frequently accessed keys and the possibility of programmable hot keys. Some keyboards do not have crucial function keys (e.g., windows key). Software programs for the keys should be utilized when available.
Do not be misled by false advertising. Product sheets accompanying the keyboard make subjective comments regarding the value of the product. There is no such thing as an ergonomic keyboard.
If the keyboard height is too low, there is increased risk of bending your wrists. If the keyboard is too high, there is increased risk for shoulder, elbow, neck and back strain.
Consider the following in determining your correct keyboard height:
If you are a touch typist, the keyboard should be at your fingertips when your hand is in neutral position, with your elbow angle slightly greater than or equal to 90 degrees.
If you are not a touch typist, you will need to have the keyboard slightly higher. The worksurface supporting the keyboard should be even to or higher than the sitting elbow.
Determine leg clearance needs. If there is less than an inch difference between the sitting elbow height and the top of the thigh, a low profile keyboard tray should be used to support the keyboard.
Account for the height of the keyboard (e.g., when fully tented, the Goldtouch is 5.5 inches; the MS Natural and Adesso Truform keyboards are 2" high).
If you are using a keyboard tray and you are a touch typist, it is best to adjust the tilt of the keyboard downward, away from you (negative tilt). If you are using a keyboard tray, but you are not a touch typist, the keyboard should be flat. Do not tilt the keyboard toward you or use the legs on the under side of the keyboard. This will cause your wrists to bend.
Keep the keyboard at the edge of the surface so your arms can rest naturally by your sides when typing. This will allow you to avoid the need to rest your forearms on the worksurface, as is the case when the arms are extended. (Note: if the keyboard is too high, you will have a need to rest due to elevated shoulders.) A non-touch typist benefits from a keyboard that is slightly away from the edge, and often needs to use a gel wristrest while resting. A wristrest should never be added in front of the MS Natural or other keyboards that have a fixed wristrest. These keyboards can benefit from use of a gel wrist pad contoured to fit on top of the hard fixed pad.
There is not much research to guide the selection of alternative keyboards. However, there is greater knowledge regarding the correct use of keyboards.
A neutral hand position when using the keyboard is flat (i.e., the knuckles should be even with the wrist). The fingers should rest in a waterfall position. The middle finger should be in line with the elbow. Suggestion: use a ruler to demonstrate the neutral, flat wrist and draw a line from the middle finger to the elbow to demonstrate no deviation. Arms should be relaxed at the sides. This position is used by experienced pianists.
Relax the fingers while typing. Move the hands to reach keys instead of extending fingers forwards and backwards, as was taught in old style typing classes (and is still promoted in typing programs). Avoid the "claw" position.
The user needs to move when keying (as if playing the piano).
Float the hands across the keyboard without resting on the wrist rest, desk or thighs while typing.
Move fingers/hand/arm together to reach keys; avoid typing using only the hands.
Move from the shoulders; do not move the hands like windshield wipers from stabilized wrists.
Move hands and arms to reach "enter", "backspace", and "shift" keys, using stronger fingers when accessing side keys.
Use a soft touch to type; avoid excessive force. Punching the keys increases strain in the forearms and causes soft tissue damage.
Never fix the thumbs or any other digit around the keyboard or worksurface.
Avoid holding multiple keys with the same hand at the same time. Use one finger of either hand for shortcut keys (e.g., use the control key on the right side of the keyboard when typing "crtl + s" to save a document).
Rest on the side of the hand (thumbs up), or let arms hang at sides.
Sit directly under the keyboard surface. Your elbows should be relaxed at your sides when your hands are on the keyboard. If you feel the need to sit away from the keyboard, it could be because the monitor is too close. Remember that the eyes lead the way.
Longer fingernails promote the "claw" hand position while typing. This will cause hand, forearm and elbow pain.
Research is showing decreased risk for some injuries if the forearm is supported while keyboarding, but the chair must recline, provide adequate lumbar support and be fully adjustable to fit you and your tasks. You still must be able to align our head with your hips and move from your shoulders while typing.