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General Seating Considerations
Your chair is the most important aspect of workplace ergonomics. You should be able to sit comfortably in the chair, using as much of the chair back as possible for support. The lumbar support should fit comfortably into the curve of your lower back, and your feet should be flat on the ground (use a footrest if necessary). The seat pan (i.e. the part on which you sit) should be an appropriate size that allows at least one inch between your legs and either side of the chair, and supports your legs without applying pressure to the back of your knees.
Adjustable Type Chairs
Adjust the Chair Height
Start with your seat at the highest setting and then adjust downward until your legs and feet feel comfortable, and the back of your knees is at an open angle (90 degrees or slightly greater, and not compressed against the floor).
Sit Back in the Chair
Adjust the height and/or depth of the lumbar support to provide comfortable lower back support. A chair with a seat depth adjustment would help to be seated against the chair’s back while maintaining a correct position at the knees.
Adjust the Chair’s Tilt Mechanism and Tilt Lock
If the chair has a recline lock, set this at a comfortable position. Remember to unlock this periodically; this will allow the backrest to move with your back as you change posture. It’s generally better to be slightly reclined, as this helps relieve tension from your lower back. If the chair allows you to, adjust the tilt tension as you move back and forth so that the chair provides consistent support.
Adjust the Seat Pan
When sitting back, make any adjustments to the seat pan (e.g., seat pan tilt) to reach a comfortable position. The seat pan should extend about an inch on both sides of your legs, and should not apply pressure to the back of your knees. A chair with a seat depth adjustment would help to be seated against the chair’s back while maintaining a position at the knees.
Adjust the Armrest
If possible, adjust the height, width, and position of your armrests to one most comfortable for how you work. The armrests height should be set to allow your shoulders and arms to be positioned at a relaxed manner. Adjustable armrests are available in height adjustable, width adjustable and models that allow the arm pads to be angled towards the center of the chair.
Make sure that the chair’s casters (wheels) move smoothly, and that nothing obstructs your ability to position the chair in front of your desk and computer.
If you don’t have an adjustable chair, consider purchasing one. It’s a wise investment because it’s such a crucial element in creating an ergonomically correct workspace. Many manufacturers offer ergonomically designed seating for executive
offices, stool style seating, workstations, as well as conference and training rooms. If you don’t have an adjustable chair, you may need to think creatively to obtain an ideal sitting posture.
• If you sit low (i.e. there’s a downward slope from your knees toward your body), consider sitting on a soft, evenly-filled cushion to provide the added height necessary.
• If you sit too high (i.e. there’s an upward slope from your knees to your body), consider using a footrest to bring your thighs to a level parallel with the ground. If you don’t have a footrest, use a firm and level alternative, such as a phone book.
• If your seat pan is too deep (which creates pressure on the back of your knees), consider putting a back pillow between you and your backrest to push your body forward and into a better position.
Tips – General Seating Recommendations
Ergonomists generally agree that there isn’t a single, “static” seated posture that should be used all of the time. It’s a good idea to move around into different postures throughout the day to improve circulation and reduce muscle fatigue. However, if you have to sit for long periods, the following posture puts the least strain on your body.
Keep open angles
• Contrary to popular belief, good posture doesn’t mean sitting flat and firm, with your hips, elbows, and knees at 90 degree angles. Your hips, elbows, and knees should be at slightly open angles (greater than 90 degrees). Sitting erect or leaning forward increases the strain on the lower back – it’s okay for short term use, but isn’t recommended for prolonged periods of time.
Keep thighs parallel with the floor
• Your thighs should be roughly parallel with the floor. Recline slightly.
• Research has shown that reclining eases pressure off your lower back.
Avoid pressure points
• Uncomfortable pressure (e.g., on the back of your knees) can impede circulation. Be sure to make the proper adjustments to your chair to reduce such pressure.
Rest your feet flat on the floor
• Your feet should be flat on either the floor or a footrest.
• Making slight adjustments to your sitting posture throughout the day is healthy.