People vary widely in their shapes and sizes, and the chairs they use should reflect this characteristic. Workers should be able to select from a variety of different chair models.
A "poorly fitting" chair may introduce musculoskeletal problems or aggravate existing conditions. Compressive forces on the spine are greater when sitting than when standing. Fatigue and discomfort result when muscles and joints are forced into awkward postures, especially after prolonged sitting.
The chair is the most intimate piece of equipment the office worker has, yet it is often overlooked in the design of a workstation. Whether in a conference room, or at a computer workstation the chair must be designed with function in mind. For example, a cozy, stylish conference chair may present problems for the office worker who types for a long period of time each day.
Currently there are no restrictions on using the term "ergonomically designed" to describe chairs or any other type of office furniture. Pay attention to the claims made by chair manufacturers.
Fitting the Population
The chair must adjust to the size and comfort of each worker. Not only should the chair raise and lower to accommodate varying heights, but the seat depth should adjust as well. If the seat depth of the chair is too great, the back support cannot be used.
An adjustable seat angle is beneficial for the office worker. A forward sloping seat, or "waterfall front," is helpful to relieve pressure on the backs of the legs while the worker is typing or writing. A 5 degree backward slope promotes use of the backrest and prevents the worker from sliding forward. The backrest should support the lumbar spine but not restrict its movement.
The armrest should be adjustable for height, width between armrests and distance to the seat front. These adjustments are important for reducing the pressure on the seat surface and the load on the spine. The length and width of the armrests must be considered. Armrests can become obstacles when they are too wide or too high (e.g., armrests that prevent a chair from sliding under a table). When awkwardly positioned, armrests may hinder a worker getting out of the chair. Five casters are necessary to prevent the chair from tipping. The casters must roll over carpeted surfaces easily.
The chair evaluation checklist, below, should guide you in selecting a chair that can be adapted to your individual needs.
Any questions answered NO indicates a potential problem area.
If
you have any questions regarding this information please contact
your supervisor or Dan
Sweetman, Environmental Health, Safety and Risk Manager,
University of Wisconsin - La Crosse, 855 East Avenue North, La
Crosse, WI 54601 EMail: sweetman.dani@uwlax.edu Telephone:
(608)785-6800 Fax: (608)785-6577
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Last modified: 08/14/02
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