An ergonomic task chair is a movable work seat with adjustable features to make it supportive to the body. A work chair is only truly ergonomic if it can be adequately adjusted to suit each worker's height and weight. The basic parts of an ergonomic task chair are: an adjustable backrest, an adjustable seat and a pedestal base.
The most supportive, or ergonomic, pedestal bases have five branches or points. Each one of these rests on an attached caster, or wheel, to allow the task chair to roll. The wheels on ergonomic task chairs must be sturdy to properly support the worker's weight as he or she uses his or her feet to roll a chair from one work area to another one nearby.
A cylindrical column typically joins the pedestal section to the seat. A lever or knob will allow each worker to change the height of the seat as needed. An ergonomic task chair is designed to be adjusted to allow enough space between the underside of the desk top and the tops of the thighs so that the worker can sit comfortably, including crossing his or her legs if desired. The edge of the seat should be designed to prevent circulation from being limited between the thighs and knees of a seated worker.
The backrest of an ergonomic task chair is best if it can be raised vertically as well as be adjusted for its slant or tilt. The backrest may be slightly padded or made of metal mesh to allow air to flow through for good ventilation. Some ergonomic task chairs feature a seat and backrest made from bands of elasticized material to better conform with an individual worker's body type. Ergonomic work chairs with armrests are designed to allow less stress on the shoulders. Adjustable armrests provide the most ergonomic benefits, as they can be changed for different body types.
The correct task chair for an individual doesn't depend solely on height and weight, but also on the particular industry. Computer workers' ergonomic task chair designs usually feature adjustable arm rests as a way of helping to prevent unhealthy conditions in the body such as carpal tunnel syndrome. Dental professionals' ergonomic task chairs are often extremely compact and able to adjust to a fairy low height as they must often be placed next to the reclining seat the patient is in.