Ergonomically, the chair is the most important element in a typical computer work station. If you are not seated correctly, there are likely to be related problems with your work station. Inadequate or improperly adjusted seating can lead to discomfort, reduced productivity, and even injury. The ergonomists in the University’s Occupational Safety Unit frequently encounter employees experiencing problems that result from improper or maladjusted seating.
Adjustability is crucial
Almost all modern office chairs are height adjustable, usually by lifting a handle just under the right side of the seat and either using your weight to push the seat down or lifting your weight to allow the seat to rise to the desired height, and then releasing the handle to lock the setting. The seat height should be adjusted so you can sit all the way back on the seat pan, with your back against the chair’s back rest and your feet flat on the floor. The back rest height must also be adjustable to allow proper positioning of the lumbar support (more about that below). If the chair has arm rests, they must be height-adjustable and should be set so they just take the weight of your arms off your shoulders. Adjustability is key, and these three adjustments should be considered the minimum acceptable.
Many chairs have adjustments for the seat pan and back rest angles. They may also have settings to allow the back rest to float with you as you move, or to allow the entire seat to tilt, in which case there is usually an associated tension adjustment.
Some chairs provide lateral adjustments for the arm rests or an adjustment for the amount of lumbar support.
Seat pan contouring, angle, and size
A chair’s seat pan must be properly sized for the occupant. If a seat is so wide that you can’t reach the arm rests, or so narrow that you don’t fit between them, the chair doesn’t fit you. Similarly, if the seat pan is so long that its front edge is pressed against the back of your lower legs, and you can’t reach the back rest, it’s not a good chair for you.
The seat pan should be angled back slightly and gently contoured for comfort, with a rounded “waterfall” front edge. Beware of seat pans with heavily sculpted contours; they tend to force you into a single seated posture rather than allowing you to shift positions.
Most chairs do a good job of holding you up off the floor; fewer do a good job of supporting your back, especially your lumbar (lower) back. Lumbar support is one of the most critical functions of the chair’s back rest. When shopping for a chair, look for a lumbar support (that “lump” near the bottom of the back rest) that fits the inward curvature of your lower back. It is usually necessary to raise or lower the back rest to move the lumbar support into the correct position. If you can’t make it feel comfortable, the chair doesn’t fit you properly.
Arm rests are somewhat a matter of preference. They can provide support to take the weight of your arms off your shoulders and reduce fatigue. Some people find arm rests get in their way and prefer chairs without. Arm rests should be smooth and well-padded with rounded edges.
Chairs for larger or smaller individuals
Seating designed for smaller or larger individuals is also available. Features such as shorter, taller, or heavier-duty cylinders, and wider, narrower or deeper seat pans can be obtained, usually by special order, to accommodate those who are not “average.”
Five star base
Most modern office chairs have a star-shaped base with five legs and casters (some even have six) to provide adequate stability when the occupant leans back. Older chairs with only four casters tend to tip over more easily, potentially causing serious injury. Obviously, stability is non-negotiable.
Correct casters for the floor
Choose casters based on the flooring where the chair will be used. Hard plastic casters roll well on carpeted surfaces, but on hard-surface floors they turn chairs into “performance vehicles” that can scoot out from under an unsuspecting person attempting to sit down. Choose soft rubber casters for hard floors.
Price, durability, repairability, and warranty
In seating, as with anything else, you tend to get what you pay for. There’s no way around it: a good chair is not cheap, but the expense is money well-spent. Good chairs tend to have better adjustability features, are better-constructed, more durable, will last longer and usually come with significantly longer warranties than their “bargain” counterparts. Good chairs can also be repaired if they break; the office store “price-buster special” usually can’t. It’s not necessary to spend a fortune for a chair, but it is important to realize that there is a world of difference between a chairs, and it is usually reflected in the price.
Try before you buy
A chair is an important investment. You want to make sure it will be comfortable for the long-term. It’s tempting to drop by an office store, check out a couple of chairs, buy the one that feels the best, and be done with the process, but it’s a poor way to select seating. You really need to sit in a chair over the course of several days or more to determine whether it will work for you. University preferred vendors can provide a “loaner” chair you can use in your space to decide whether it is truly comfortable before you purchase it.
The Occupational Safety Unit can provide you with ergonomic assessments, assistance in selecting chairs and other office equipment, as well as other services. You can reach us by calling Environmental Health and Safety at 275-3241 during normal business hours.
QUESTIONS or COMMENTS?
Contact EH&S at (585) 275-3241 or e-mail EH&S Questions.
This page last updated 1/30/2013. Disclaimer.