The Influence of Seat Angle on Forward Trunk Inclination During Sit-to-Stand

Abstract

The purpose of this study was to investigate the influence of seat angle on forward trunk inclination during sit-to-stand (STS). Fifty-two healthy subjects (26 male and 26 female, 20.8 ± 2.9 years old) participated in this study. Seat angles of 5, 10, 0, -5 and -10 degrees were selected. The angle of forward trunk inclination, leg angle and STS time were measured during STS. Data were gathered using a two-dimensional movement analysis system. The results showed that: 1) the angle of forward trunk inclination increased significantly at 5 and 10 degrees, and decreased significantly at -5 and -10 degrees compared with 0 degrees, 2) the leg angle decreased at 5 and 10 degrees, and increased 5 and -10 degrees compared with 0 degrees, and 3) the STS time was prolonged significantly at 10 degrees compared with 0 degree. A significantly negative coefficient of correlation was found between the angle of forward trunk inclination and the leg angle. A significantly positive coefficient of correlation was found between the angle of forward trunk inclination and the STS time. It was clarified that the angle of forward trunk inclination was increased during STS by the backward tilt of the seat angle. The increase in the angle of forward trunk inclination probably limits some of the activities of daily living for the elderly and hemiplegic disabled, which requires STS, such as transferring from a wheelchair to a bed or a toilet. It was suggested that the seat angle must be adjusted to correspond with the purpose of the activity in order to eliminate such difficulties.