Typical examples of STS movements from the seat heights of six different heights (10, 20, 30, 40, 50 and 60 cm). Time = 0 (%) indicates the instance when the buttocks lost contact with the chair (seat-off time). Time = 100 (%) indicates the finish time of each STS movement. Stick figures were drawn at 10% time intervals. The gap between the center of hip joint and the surface of chair seat is due to the existence of the thickness between the center of hip joint and the skin surface of buttocks.