The ergonomic office chairs selected for inclusion in the study were sourced from various international manufacturers.
All of the chairs included were in widespread distribution and use at the time of this study. Each chair was chosen for its differences from the others, whether it was as dramatic a difference as its fundamental engineering design or as simple a difference as a variation in the type or thickness of the seat pans’ foam or fabric. In an effort to avoid commercialism, no mention will be made of the chair makes or models. Instead, a brief description of their basic designs is tabulated with a corresponding ‘‘chair code’’ which is used for chair identification. The chair descriptions themselves are purposely kept brief and general since with a sufficient description a knowledgeableergonomist could easily recognize many of the chairs. This type of identification is deemed to be appropriate since the goal of this study was not a detailed investigation of chair design variables, but rather a comparison of whether basic differences in chair designs or changes in subject posture had a greater impact on subject-seat interface pressure distributions. Table 1 is a list of the chair descriptions and the corresponding identifier codes used in the experiment. All chairs had a five-point base, a hydraulic/pneumatic main support cylinder, a backrest, and armrests.