Analysis of Force Applied to Horizontal and Vertical Handrails with Impaired Motor Function.

People depend on medical equipment to support their movements when their motor function declines. Our previous study developed a method to estimate motor function from the force applied to a vertical handrail while standing. However, the effect of the handrail direction on movement remains unclear. Additionally, the force applied to the handrail and floor reaction forces on the buttocks and feet may also change with a decline in motor function. Here, this study constructed a system with force plates and handles in both the horizontal and vertical directions to measure the forces applied to the handrails, buttocks, and feet. Furthermore, the change in accuracy of the estimation of motor function, depending on the direction of the handrails and input information, was investigated. In the experiment, healthy participants stood up using a handrail with unrestricted movement and while wearing elderly experience kits that artificially impaired their motor function. The results showed that people exert more downward force on horizontal handrails than on vertical handrails. However, people rely on the vertical handrail for a longer period of time to stabilize anterior-posterior movement. These results indicate that different directions of handrails cause different strategies of the standing-up motion. Additionally, the accuracy of the estimation of motor function improved when the horizontal handrail was used rather than the vertical handrail. This suggests that the classification accuracy could be improved by using different handrail directions, depending on the subject's condition and standing-up motion.