DESIGNING A TRULY ERGONOMIC WORK STATION

Let's say you're about to design a user-friendly work station. It's important to remember that a well-designed office work environment is made up of several critical components:

1. The chair.

Ergonomically, the most important piece of office equipment is the chair. "Low back pain remains the most prevalent and costly work-related musculoskeletal disorder," says a leading health insurer. Low back pain can be the direct result of sitting for days, months and years in poorly adjusted chairs. The typical office worker will spend more time sitting in an office chair than anywhere else, with the possible exception of bed. With all this time spent together, it's critical that task chairs meet these human criteria.

Task chairs should encourage movement. Frequent movement and position changes are critical to health and comfort. However, in order to get people moving, they must first know how to operate their chairs. And this is easier said than done. According to a 1995 study, less than two percent of the subjects were able to identify the purpose of the back tension adjustment knob--the most basic of chair controls--on a variety of chairs. The problem is that if the tension spring is set too firm, the chair won't recline and the user will be forced to sit in an upright posture. If the spring is set too loose, the chair will fall back to its most reclined position, where the user may sit for hours at a time. Even if set properly, the tension spring will only provide optimal support in the middle of the recline range.

To accommodate for these inherent failings of the tension spring, many chairs are equipped with recline locks. But locks can also be dangerous exactly because they're designed to keep the chair in a fixed position. The solution? Adjust the spring tension to best support the user. Also, use locks with caution and conscientiously unlock them on a frequent basis to change recline positions.

Recline is healthy. Nowadays, researchers everywhere agree that reclining is healthy. The renowned industrial designer Niels Diffrient once said, "The more you recline, the more comfortable you get. Ergo, the best chair is a bed." Essentially, the more work you can perform while reclining, the more of your body weight will be distributed to the backrest of your chair, and the less pressure your spine will have to endure. However, extended recline can put additional stress on your neck and shoulders while they work to maintain the upright position of your head. Therefore, it's wise to consider a chair with a headrest if you expect to perform extensive work in a reclining position.

	Disc pressure in the spine varies with the different seated postures assumed during a typical work day. As shown, the spine sustains far less pressure when reclined, which translates into more comfort and less risk of injury.

Task chairs should fit the user. In addition to proper support, it's important that a task chair provide good body fit. No one would consider wearing a pair of shoes that didn't fit. Yet millions of office workers sit in chairs that are maladjusted to their body size and shape. Not surprisingly, such workers are at high risk of injury. Since office workers come in all shapes and sizes, it's vital that each worker's chair be sized to fit. The most common size adjustment is seat height. Ideally, the seat height should be set so the user's feet rest comfortably on the floor while the upper body is high enough to work comfortably at the desk. But because the height of most desks is fixed, petite users may need to raise the chair to a point where their feet are lifted off the floor. This. puts undue stress on the undersides of the thighs, often causing circulation problems and potential nerve damage. Placing a height-adjustable footrest under the desk solves the problem by giving petite workers proper support for their feet and legs.

Seat depth. Here the primary concern is to provide maximum surface area on which to distribute the body weight, while keeping the delicate area inside the knee clear of potential contact stress from the front of the seat. When sitting with your back properly supported, there should be approximately two to four inches of space between the front of the seat cushion and the inside of your knee.

Backrest height. As with seat depth, the idea of adjustable backrests is to maximize surface contact and minimize pressure points. While the curvature of the spine varies somewhat from person to person, it is the position of the curvature that matters. Thus, a contoured and height-adjustable backrest provides lumbar support while maximizing surface contact and weight distribution.

Armrests should be adjustable and kept level. Armrests should be quickly and easily adjustable. That's important because different tasks and different sized users require different armrest positions. In addition, users should be encouraged to keep their armrests level. Otherwise, they will sit, possibly for years, with one arm lower than the other and their spine therefore in a lateral curve. And that's a high risk posture for injury.

Ultimately, when it comes to seating, it's critical that users be trained to fully understand the features and operational controls on their chairs in order to gain the most benefit from this extremely important work tool.

Click here for information on Humanscale's seating solutions.