Time Based Subjective Evaluations of Seated Cushion Comfort

摘要

The detrimental effects of prolonged sitting during long-duration flights include deep vein thrombosis, pressure sores, and decreased awareness and performance. Oftentimes, the cushion is the only component of the seat system that can be modified to mitigate these effects. In addition, it is the cushion that has a direct connection to the seated subject, and thus directly influences his perception. Several studies were undertaken at Wright-Patterson Air Force Base (WPAFB) in Dayton, Ohio to evaluate the long term cushion comfort of a diverse population. Test times ranged from four to eight hours of sit time during each test session. Variables measured included seat interface pressure, oxygen saturation in the lower extremities, muscle fatigue along the back, a cognitive performance task, and subjective evaluations. This study investigated the effect of time on the subjective evaluations from four different studies. It was found that the subjective variables most influenced by time were center/lower back and buttocks, while the shoulder and lower leg variables had no time effect. When the subjects were asked to rate their cushion preferences, it was found that approximately six hours were necessary before the subjects opinions of the cushions no longer changed. This finding is important for tests where the Air Force evaluates cushion options for different missions that may last nine hours or longer. These results and research are relevant to the seating industry whether they are for office, transportation or industrial environments as subjective evaluations are often conducted in order to obtain the best choice for the setting. However, it is important to know before these surveys are conducted, how long a subject should sit in the seat before opinions are collected.