Abstract
This study examined the flexion angle of the trunk of the human body when descending stairs hastily. In recent years, the number of accidental falls among the elderly when descending stairs has increased, so urgent measures need to be taken prevent such accidents. This study focused on the flexion motion of the trunk which indicates the state of balance of the body, and examined the mechanism by which such trunk flexion is controlled when descending stairs at different speeds. The subjects in this study were four elderly males and four elderly females. The subjects descended a three-step stair at four speeds (slow, suitable, fast and very fast) while a motion capture system measured their trunk flexion angle. The results showed that as the speed of descent increased, the trunk flexion angle decreased, especially at the second step, when compared with the first step. This occurred because the degree of trunk flexion corresponded to the compensation motion needed to descend the stairs hastily. Due to these factors, trunk flexion was reduced in order to keep the body in balance. The trunk flexion angle of the female subjects decreased significantly more than that of the male subjects. This was due to the lower muscular strength of the female subjects, combined with their higher awareness of danger, so that they were less able to control their body motion. In this study, it was concluded that elderly people need to take greater care when descending stairs, especially on and after the second step.
