Ergonomic chairs are designed to help reduce the risk of injuries, but what happens when an employee is already injured? From saddles and stools with a spring-loaded base to exercise balls, chairs that promote different seating styles and options are often prescribed for workers who aren’t at the peak of physical health. Musculoskeletal disorders (MSDs), like back pain and upper extremity disorders, may be the worker’s problem, but are these “weird” chairs really a solution?
Yes, says Eileen Vollowitz, BS, PT. And it’s all in the open thigh-torso angle built into the chairs’ designs.
Vollowitz, whose company Back Designs sells some of the “odd” chairs (and some traditional ergonomic chairs, too), believes that for a worker with a back injury, for example, one of the non-traditional chair styles can alter the way a worker bears weight while sitting and therefore can help him or her perform work.
“People with back problems may have a problem with weight bearing,” says Vollowitz. “Others have reduced tolerances for being in any one position for too long, or are sensitive to contact pressures.” While the same be the case for some healthy workers as well, Vollowitz says, injured workers tend to become symptomatic more quickly.
Vollowitz describes how different sitting styles affect weight bearing in the report “Furniture Prescription For the Conservative Management of Low-Back Pain,” (1988, www.backdesigns.com).
“Sitting is a weight-bearing activity. Weight-bearing is usually least in a posterior sitting and greatest in forward sitting since the backrest on a forward chair cannot be used in forward postures. If the task and work-surface height allow users to lean on their arms, if the chair has a front support for the torso or pelvis, or if the feet are positioned directly beneath the body’s center of mass (as with saddle-sitting), weight bearing during forward sitting postures is greatly reduced. Weight bearing is further reduced in erect and posterior seated tasks with larger backrests and well-fitted armrests.”
For the injured worker, a reduction in weight bearing while sitting can be one of the keys to pain management in the workplace, Vollowitz says. But, while a large backrest and armrests might achieve this desired reduction, some tasks, including some desk-tasks like writing and for some people, using a keyboard, are actually forward seated tasks
This article originally appeared in The Ergonomics Report™ on 2004-12-01.