Effect of Wheelchair Tipping Lever Form and Location on Stepping Operation of Helpers

Abstract

 In order to navigate a wheelchair over steps, a helper must depress a tipping lever to lift the front wheels. The present study investigated several tipping lever designs to clarify their ease of operation and the physical strain of people who help elderly people. These designs included three type of surfaces, and six locations (three lengths, two heights). Fifteen females in their 60s participated as wheelchair helpers, and two young males participated as wheelchair users. During locomotion, plantar pressure, posture angle, and surface electromyography were measured. After operation, the helpers subjectively evaluated the physical strain of the operation. The results indicate that both the cylindrical and flat surface levers covered with robber, as compared to the uncovered cylindrical lever, were more suitable based on subjective evaluation with regard to “ease of lifting” and “ease of depressing the lever,” as well as depression area. Regarding lever location, the longer tipping lever (over 40 mm at both heights) relatively improved the helper’s condition, according to their subjective evaluation. In addition, the pressure center of the plantar pressure was on the heel side, and decreased the electromyogram activity. Under conditions of low height, the hip and knee joints of the caretaker significantly expanded. On the other hand, the speed of the wheelchair and the ride comfort of the passenger did not significantly differ across all conditions. These findings suggest that subjective physical strain and electromyogram activity of wheelchair caretakers can be reduced by improved lever surface and length.