The effect of perception of seat width on back-to-sit task

[Purpose] The movement trajectory in daily motion is strongly associated with information regarding the properties of the environment. In the case of the back-to-sit task, it may vary according to chair property. The purpose of this study was to investigate whether trajectory formation in back-to-sit tasks by healthy adults depends on seat width information. [Participants and Methods] Ten healthy young males performed a back-to-sit task in 5 seat width conditions (80%, 90%, 100%, 110%, and 120% of each participant's buttock breadth). The motion analysis system and force plates were set at a sampling frequency of 250 Hz. The spatial and temporal variables were calculated to examine the effect of seat width. A questionnaire was also administered to examine whether the participants were aware of each seat width in comparison with their own buttock breadth as narrow or large. [Results] The questionnaire results showed that many participants were aware but some were unaware of the relative comparison of their size to the seat width. Nevertheless, the spatial and temporal variables were invariant under the different seat width conditions. [Conclusion] In healthy adults, the trajectory formation in back-to-sit tasks is not dependent on the perception of seat width information under their variability as per daily situations.