The obese office worker seating problem



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A field study was performed using 51 participants that were randomly selected from several Brazos Valley, Texas businesses to participate in an 8-hour assessment of office seating habits that influence seating design and testing. A control group was established as those with BMI?s < 35 and an obese group was established as those with BMI?s >35. Data was collected through written survey and through data logging of seat and back contact pressure (average and peak), surface area, center of gravity and duration of contact by recording 8 metrics, once per second using the X-sensor pressure mapping device and software. Additionally, 50 days of caster roll distance was recorded for the participants using a caster mounted digital encoder. It was determined that at alpha = 0.05, using the Student?s T-test, a significant difference did exist between the groups in mean seat time per shift (p<.001) back contacts per shift (p<.002), seat contacts per shift (p<.01) and caster distance rolled per shift (p<.001). During a subsequent lab study, data were collected during 3 cycles of ingress, egress on the armrest use, along with anthropometry and critical chair testing parameters. Center of Gravity was measured from a fixed backrest (front to rear) for 16 participants. 4 male and 4 female obese with BMI greater than 35 and 4 male and 4 female with BMI less than 30 were compared. The purpose of this study was to determine whether a significant difference existed between anthropometric factors for normal and obese participants that would affect how a chair should be loaded during testing. The null hypothesis that normal means and obese means for each measure were equal was rejected by using independent samples T-test at alpha = 0.05 with p<.001 significance reported for all measures. These data suggest a need for a fresh look at several parameters used in the normal test standards as well as a need for a tougher test method for seating designed for the obese worker.