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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 . |
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