Always check your working position when using a computer. To avoid unnecessary discomfort, make sure the following key principles are in place:
When looking at your work, your neck should be in a neutral, relaxed position. Position the monitor directly in front of you to avoid turning your neck to the side.
The monitor screen should be positioned so that you do not have to bend your neck up or down to see the screen. The top of the screen should be approximately 2-3" below seated eye level.
The monitor should be positioned 20 to 30 inches away from you (slightly more than an arms length. Adjust as needed for your visual comfort.
If you must use a telephone simultaneously with the computer, use a headset. Never try to hold the handset between your shoulder and ear. If you do use a telephone handset, position the telephone close to you to avoid over-reaching.
Your feet should be positioned flat on the floor or on a footrest if necessary.
Your chair should provide you with good back support. Maximize the contact of your back with the chair's backrest with the use of adjustments or cushions as needed.
It is often useful to have armrests. However, they should be adjustable in height and width to allow for resting the arms with your shoulders in a relaxed position.
The seat depth should be sufficient to provide support under your thighs. There should be approximately a two-finger width space between the edge of the chair and the back of your knees.
Arm and hand positions
Your keyboard and mouse should be positioned at a height to allow for a slightly open elbow angle. Elbows should be at about a 100 degree angle. If you cannot adjust your keyboard height, raise your chair and use a footrest or elevate your table on blocks as necessary.
Your keyboard should be placed as flat as possible or slightly down, so that the wrists can be placed at a neutral position. Your hands should be slightly lower than your elbows with your fingers pointing toward the floor. (NOTE: If you recline back in your chair, you might not need to tilt the keyboard. Check the alignment of your wrist and set the angle of the keyboard as needed. Your sitting posture will affect how you adjust your keyboard and mouse).
If you use a keyboard tray, it should be large enough to accomodate your mouse.
If you use a wrist rest, use it to support your palms only when pausing between keying. Do not place your wrists on the rest and turn your wrists from side to side to key. This increases the strain on your wrist.
Your mouse should be positioned within easy reach. Over-reaching can result in shoulder and/or arm discomfort.
Use a lighter touch on the keyboard to reduce impact on your wrists.
Place a document holder directly next to the computer screen if you will be referring to documents often while typing.
Periodically refocus your eyes on an object at least 20 feet away. This will help reduce eye strain resulting from focusing on a single depth for prolonged periods of time.
Take frequent "microbreaks," at least every hour. This should be a moment when you stand up, stretch, stengthen, and/or adjust your seated posture.
Change your posture throughout the day. Static postures are bad for your circulatory system and muscles.
Aim for alternating your posture every 15 minutes.
Perform at least 15 minutes of non-keying work for every two hours of typing.
Never cradle the telephone between your shoulder and neck while typing. Consider using a hands-free headset for prolonged or frequent phone use.