Using your computer can be a pain in the neck?literally. If you r monitor is not positioned correctly you may be tilting your head to view, causing headaches and neck pain. A keyboard that's not positioned correctly can lead to discomfort in your wrists, while an improperly adjusted chair may cause lower back or leg pain.
Wrists
Typing can be stressful on the wrists. Stress on your wrists can be reduced if you keep your wrists relatively straight while typing. It is natural to have your wrists bent slightly upward and outward while typing. Consider using a wrist rest in front of your keyboard in order to help keep your wrists straight. The wrist rest should be soft and arranged so that your wrists "float" just above it while typing. Your wrists should not "rest" on the wrist rest during typing - only when you are resting. Likewise, providing support for your arms, such as adjustable arm rests on your chair, can also help keep your wrists straight.
Keyboard and mouse location
The keyboard and mouse should be located lower than your elbow. If they are higher or are located too far away, it causes your shoulders to hold up the weight of your arms while you are working. This becomes very tiresome and results in shoulder, neck and backache. If possible, lower your keyboard and mouse, and bring them closer to your body - a keyboard extension shelf can help. If a keyboard extension shelf is not available, raise your chair - but make sure that your feet remain firmly on the floor. If you have adjustable arms on your chair, they should be adjusted to provide arm support while you are typing.
Chair
Sitting is very stressful on your lower back. This can be minimized if you maintain the normal curvature in the "hollow" of your back while you work. You should concentrate on maintaining this posture while working - it quickly becomes common practice. If your chair has adjustable lower back support, adjust it so that it provides firm support. A cushion or rolled up towel can also provide lower back support.
The chair height should be adjusted so that your feet are firmly on the ground and so that the angle at your knee is 90 degrees or greater (the seat should be higher than the bottom of your kneecap). A footrest is helpful if your chair needs to be higher in order for you to use your keyboard and screen