A well–designed chair will favorably affect posture, circulation and the extent of strain on the spine. The chair should allow you to place your feet firmly on the floor or a foot rest, with your hips slightly flexed and your knees at a 60–90° angle. The seat should be comfortably wide, and the backrest about 6 to 9 inches high and 12 inches or more wide in the lumbar region. Most chairs used by computer users has adjustments to make it comfortable to sit on, but few people bother to adjust it. Spending a little time learning how to adjust the chair and set it correctly can go a long way in preventing back pain. With the hips at 90°. However, a great deal of recent research supports the idea of a much wider hip angle – with 130° or so as an “Optimum” angle. The reason? When the hips are straightened, the vertebrae of the lower spine are aligned with each other in a way that reduces and evens out pressure on the intervertebral discs. Further, sitting upright is less desirable than reclining. When reclining, the lower back muscles work less and the spine supports less weight, since body weight is held up by the chair’s backrest.
Take a break!
Conventional practice recommends rest breaks about 15 minutes long, every two hours or so. This is insufficient for work such as typing. Research supports the idea of very short breaks done very frequently – for example, 30–second breaks every 10 minutes or so. Taking a break can be as simple as taking your hands off the keyboard and letting your arms droop at your sides. These should happen in addition to the normal fifteen–minute coffee breaks, when you should get up from your chair and do a few exercises to loosen your neck and shoulder muscles.
Reduce glare to avoid eye strain
- Avoid light shining directly into your eyes or onto your screen.
- Hold a mirror in front of your screen to identify sources of glare.
- Avoid placing the computer directly under a bank of lights.
- Lower lighting levels to about half of the normal office lighting.
- Use task lighting if necessary.
- Position the screen at a right angle to the window.
- Use window curtains or blinds if necessary.