Helper's Wheelchair Navigating Indexes for Passing Stair Steps that Considers both the User's Riding Comfort and the Helper's Physical Strain

Abstract

　The present study investigated the relationships among the posture and physical strain of wheelchair helpers, wheelchair locomotion, and the riding comfort of users to establish the desirable navigation indexes for lifting a wheelchair over steps.
　Eleven women in their 60s participating as helpers lifted an occupied wheelchair over eight different step heights ranging from 5 to 150 mm. The posture of the helper and both the helper's and user's subjective evaluation were assessed as the front and rear wheels of the wheelchair were lifted over the step. User's riding comfort was significantly related to the distance between the front or rear wheels and step entrance just before lifting and the peak height of the lifted front or rear wheels. The helper's physical strain was related to the peak height of the lifted rear wheels. The peak height of the lifted front and rear wheels increased and the user's riding comfort decreased as the helper's elbow angle increased. Furthermore, an increase in the axillary angle, which increased the peak height of the rear wheel, reduced the helper's physical strain, and increased the user's riding comfort. This study suggests that the helper's physical strain and user's riding comfort can be improved by adjusting both the front and rear wheel position before lifting and the posture of the helper when lifting a wheelchair.