1. Mouse measure
First, Keep mouse and keyboard close to edge of table to reduce forward arm extension; Second, Keep mouse close to keyboard to reduce lateral arm extension; Third, Try to move the mouse by arm instead of wrist to reduce wrist extension.
2. Elbow measure
First, begin by sitting comfortably as close as possible to your desk so that your upper arms are parallel to your spine. Rest your hands on your work surface (e.g. desktop, computer keyboard). If your elbows are not at a 90-degree angle, adjust your office chair height either up or down.
3. Thigh measure
Check that you can easily slide your fingers under your thigh at the leading edge of the office chair. If it is too tight, you need to prop your feet up with an adjustable footrest. If you are unusually tall and there is more than a finger width between your thigh and the chair, you need to raise the desk or work surface so that you can raise the height of your office chair.
4. Calf measure
With your bottom pushed against the chair back, try to pass your clenched fist between the back of your calf and the front of your office chair. If you can’t do that easily, then the office chair is too deep. You will need to adjust the backrest forward, insert a low back support (such as a lumbar support cushion, a pillow or rolled up towel), or get a new office chair.
5. Low back support
Your bottom should be pressed against the back of your chair, and there should be a cushion that causes your lower back to arch slightly so that you don’t slump forward or slouch down in the chair as you tire over time. This low back support in the office chair is essential to minimize the load (strain) on your back. Never slump or slouch forward in the office chair, as that places extra stress on the structures in the low back, and in particular, on the lumbar discs.
6. Resting eye level
Close your eyes while sitting comfortably with your head facing forward. Slowly open your eyes. Your gaze should be aimed at the center of your computer screen. If your computer screen is higher or lower than your gaze, you need to either raise or lower it to reduce neck strain
Adjust the armrest of the office chair so that it just slightly lifts your arms at the shoulders. Use of an armrest on your office chair is important to take some of the strain off your neck and shoulders, and it should make you less likely to slouch forward in your chair.
No matter how comfortable one is in a workstaion, prolonged static posture is not good for the back, hand and is a common contributor to back and hand problems and muscle strain. Remember to stand, stretch and walk for at least a minute or two every half hour. Even a quick stretch or some minimal movement – such as walking to the water cooler or bathroom – will help.