Effects of different assistive seats on ability of elderly in sit-to-stand and back-to-sit movements

The ability to perform sit-to-stand (STS) and back-to-sit (BTS) movements is important for the elderly to live independently and maintain a reasonable quality of life. Accordingly, this study investigated the STS and BTS motions of 28 healthy older adults (16 male and 12 female) under three different seat conditions, namely nonassisted, self-designed lifting seat, and UpLift seat. The biomechanical data were acquired using a three-dimensional (3D) motion analysis system and force plates, and were examined by one-way repeated-measures ANOVA to investigate the effects of the different seat conditions on the joint angle, joint moments, and movement duration time (α = 0.05). No significant difference was observed in the STS duration among the three test conditions. However, the BTS duration was significantly increased in the UpLift seat condition. Moreover, the peak flexion angle of the hip during STS motion was also significantly higher in the UpLift condition. For both motions (STS and BTS), the lifting seats significantly decreased the knee and hip joint moments, but significantly increased the ankle joint moment. Moreover, compared to the nonassistive seat, both assistive lifting seats required a greater ankle joint strength to complete the STS and BTS motions.