Ergonomic Keyboard and Mouse Use
Most interactions with a computer involve using a keyboard and a mouse. The keyboard allows the user to type letters and numbers and the mouse allows the user to position the cursor, draw and execute program functions by clicking mouse buttons. Overuse of the keyboard and mouse, especially when these are being operated with the hands in a deviated posture (bent up or down or to the side), can cause painful musculoskeletal disorders, such as tendonitis, tendosynovitis, and carpal tunnel syndrome.
Consequently, a variety of alternative ergonomic designs for these devices have been developed. Most conventional keyboard designs include four separate key areas:
1) Alphanumeric area with letters, numbers, and some control keys
2) Area with cursor keys and other function keys such as input, delete, page up/down
3) Numeric keypad area that primarily has number keys
4) Function keys, the 'F' keys
Keyboard Keys or Mouse
Besides basic typing, many other actions can be performed on the keyboard using function keys, cursor keys, control keys or keyboard macros. However, many all these actions are duplicated by mouse use. These days many users choose to operate the computer by mouse rather than using keyboard keys. For good posture, it's important to align the center of your body with the center of the part of the keyboard you use the most, usually either the alphabetic area or the numeric keypad.
Keyboard Layout and the Hands
Computer keyboard alphabetic layout follows the original QWERTY design of the first typewriter. Almost from the beginning of typewriter design, it was recognized that angling and splitting the keys into halves would reduce side bending off the hands. The first split keyboard typewriter was manufactured in 1886 in Syracuse, New York.
In the 1970s the idea of splitting and angling the keys was incorporated into ergonomic computer keyboard designs where the alphanumeric keys are separated at an angle into two sloping sections. For a non-touch typist, this design can be difficult to use and thus, some keyboards only angle the keys without splitting these into halves. The split design reduces the sideways bending of the hand but, it is also important to flatten the keyboard to reduce the vertical bending of the hand.
For most people a regular keyboard design works just fine if it's put in the proper neutral position. Simple actions, like retracting the feet at the back of the keyboard or putting the keyboard on a tray with a slight downwards tilt can help to improve hand posture. Keyboards are available in either left-handed (keypad on the left) or right-handed configurations.
Computer Mouse Considerations
The shape and the location of the mouse relative to the keyboard are important considerations for a computer mouse and, several ergonomic designs are available. Mouse buttons should:
1) Be easy to click
2) Be easy to move
3) Cursor should move accurately on the screen
Some mice offer programmable buttons that allow you to control some additional computer functions from the mouse itself. The important things to check are:
1) The size and the shape of the mouse comfortably fits your hand.
2) You can hold the mouse with your hand in a neutral posture (your hand should not be bent up or down or sideways).
3) You can position and operate the mouse with your upper arm relaxed and as close to your body as possible, not reaching forwards or out to the side to do this.
To help with this, some computer keyboards have a separate numeric pad which allows the mouse to be located closer to the keyboard (for right-handed use). Some keyboards incorporate a cursor positioning device such as a trackball, touchpoint or touchpad. Use of such device avoids having to reach to a mouse.
What is Ideal?
There is no universally "best" keyboard or mouse design. Some people like to use other input devices, such as a trackball, touchpad, or pen mouse rather than a regular mouse. What works best for you is what you find most comfortable and easy to use and what you can use with your hands in a neutral posture. If you do a lot of typing and mousing, your hands will get tired with even the best designs. So remember to take frequent short rest breaks to let your muscles recover. Working in this way will help to protect you against computer-related injuries.