Analysis of trunk movement at different speeds of motion when rising from the bed with trunk rotation: comparison of free and slow speeds

Abstract

This study aimed to quantify the trunk movement angle when rising from the bed using a calculated local coordinate reference system. A total of 11 healthy male subjects participated. Subjects were assigned to 2 types of motion, free (n=6) and slow (n=5), when rising from the bed using the rolling motion previously described by Sarnacki. Motions of rising from the bed were recorded using four video cameras. The trunk angles of the local coordinate reference system were calculated using 3-dimensional analysis. The peak trunk angle, at both the free and slow speeds when rising from the bed, was obtained. The unpaired t-test was used for the statistical analysis. The trunk rotation angle was significantly greater for the slow speed motion than for the free speed motion (p>0.05). The trunk lateral flexion tended to be higher in the slow speed motion than in the free speed motion (p=0.07). Rising from the bed with a slow speed of motion decreased the contribution of momentum compared to when the subject rose from the bed with the free speed motion. A significant increase in the trunk angle for the slow speed motion assisted displacement of the center of mass of the upper body within the base of support formed by the upper extremities.