How To Make Sure You're Sitting Pretty

When you're tired, a chair is a most inviting piece of furniture. But for someone who sits for long stretches at a desk or in front of a computer terminal, chairs can become instruments of torture. Poorly designed and improperly adjusted chairs can contribute to a variety of ailments, from backaches and neck pain to repetitive-motion injuries.

Chairmakers are responding to such problems with more ergonomic designs. Today, for $500 to $2,000, you can buy chairs that give you maximum support and flexibility. One new model props up your back with an airbag. Another shifts automatically to relieve pressure on muscles.

The most important feature to look for is a backrest that supports the lumbar curve. "The biggest problem with seating," says Rani Lueder, an ergonomist in Encino, Calif., "is that it rotates the pelvis forward and flattens out the lower back."

Most ergonomic chairs, such as the Bulldog from Knoll Group, which lists for $870, correct this by building a curve into the backrest, which can be raised or lowered to suit the user's height. The Comforto System 18 ($752) by Haworth accommodates different back sizes with a movable bar that's built into the lumbar region of the backrest. Ergo Tilt ($1,045), by Neutral Postures, supports the lower back with an inflatable airbag. An ergonomic chair also should allow you to lean back slightly without forcing the seat to come up and raise your feet off the floor. This widens the angle between your thighs and torso, opening up the body and increasing blood flow. Leaning back also reduces compression on the spine, which causes people to shrink as they age.

Some chairs tilt forward as well--a handy feature if you punch data into a computer or hunch over a microscope. The chair's tilt displaces pressure from the spine onto the thighs and feet. That's the principle behind the balans, a backless kneeling chair that is supposed to encourage a healthy lumbar curve. But ergonomists warn that people slouch in the balans chair, defeating its purpose.

Adjustable armrests are important to take weight off the neck and shoulder muscles. Grahl's Hugger ($615) has movable elbow rests designed to support the arm and prevent carpal tunnel syndrome, a nerve inflammation in the wrist caused by repetitive motions. The chair's "duo back" design fits two separate backrests to either side of the back, supporting it without putting pressure on the spine.

Which chair is best? "It all depends on the individual," says Mark Sanders of the Human Factors Society, an ergonomists' group. "And to test chairs, you can't just sit in them for five minutes."

MOVE AROUND. Even the best chair won't eliminate all ergonomic hazards--lighting and body positioning are also keys to comfort. And the best antidote for backaches and pains is to get up and move around. Chairmakers are trying to cover that angle, too: Rudd International's Cyborg chair ($1,457) actually moves for you. Its weight-activated mechanism causes the chair to budge periodically just enough to relieve muscular and circulatory stresses that build up from sitting. The Federal Aviation Administration was impressed: It recently outfitted some of its air-traffic controllers with Cyborg chairs.

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