Lower-limb moments during sit-to-stand movement with different handrail grip position and trunk tilt angle

Reducing the burden on the lower-limb joint can improve the quality of life for individuals who encounter difficulties in sit-to-stand movement due to weak lower limbs. This research compared several conditions in which the handrail grip position and the trunk-tilt angle differed in terms of the moments of the lower-limb joint. It was determined that the maximum reduction of hip moment occurred when the participants stood up from an erect sitting posture with the grip position above the great trochanter. The maximum reduction of knee moment was observed when the participants stood up at a tilt angle of 30° with the grip position above the great trochanter. In contrast, the participants preferred another condition whereby the upper body was tilted 30° and the handrail grip position was located beneath the chest. Moreover, two types of strategies for handrail use were observed among the participants. In one strategy, the handrail is primarily used when the gluteal region separates from the chair's surface. In another strategy, the handrail is used during the entire STS movement. These results aid in the determination of the optimal conditions required for handrail use.