Objective. The vertical slope in sidewalk is a big barrier for the wheelchair users. In Japan, the Law for Promoting Barrier-free Transport and Facilities for the Elderly and the Disabled and it's guideline indicate that the vertical slope in sidewalk is expected to be 5% gradient or less and it can be allowed 8% or less when it is unavoidable. Grounds of this guideline depended from existing studies and related documents reported that most of wheelchair users were able to climb up 5% gradient slope and 24/25 subjects were able to climb up 8% slope. However, the research on the relationship between the feature of slope with gradient, distance, ascending speed and the physical load of wheelchair users was still remained. The purpose of this study is to evaluate the physical load of the wheelchair users by the oxygen uptake values and the wheelchair driving force while they are propelling a wheelchair upward on a slope, and to realize barrier-free environment.
Methods. The dynamic wheelchair driving force was measured by using a torque meter equipped on a wheelchair to analyze the required force when ascending on a slope. The oxygen uptake values and heart rate were measured with the portable metabolic analysis system and the heart rate monitor system. Unimpaired adult subjects were asked to propel the wheelchair on the slope that was used for the emergency escape route of the handicapped person's sports facilities. The profile of the slope was 8% gradient, 120m distance, and 7.6m height. The strokes and speed to propel the wheelchair was set to be free of each subject.
Results and Conclusion. The Oxygen Cost Index of the wheelchair users while propelling manual wheelchair upward on the slope indicated approximately 0.017 (liter/one meter) and it was about three times higher than that of by flat floor in the room (0.006 l/meter). The averaged heart rate value at the summit of the slope showed an increase of 150bpm, and was equivalent to the Borg Scale 15 (hard). It was corresponding to the feeling of physical load (it was a very hard, limit) with all subjects. The averaged wheelchair driving power while ascending the slope presented approximately 58W, and it was needed by about four times as large as flat floor (15W). We conclude that 8% gradient and 120m distance of the slope cause extremely high physical load for the wheelchair users even in the case of unimpaired persons. So, we should pay attention to the slope gradient of guideline, and should improve the slope of sidewalk to reduce the physical load of wheelchair users. The Oxygen Cost Index and the power of wheelchair driving force are useful index for the assessment of barrier-free road environment, route selection with lower stress, and the universal design of slope.