Page 10 - Mobility Management, October/November 2019

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How Vibration Impacts Power Wheelchair Users
Today’s complex rehab power wheelchair is a multi- tasking road warrior. It gets its user from Point A to Points B through Z, but it also positions (tilt, recline, elevation, standing!) to improve function, to provide pres-
sure relief, and to facilitate activities of daily living.
Complex rehab power chairs are designed to navigate a wide range
of terrains, indoors and outdoors. Those terrains inevitably include bumps, which cause vibrations. And because these consumers spend so much time in their power chairs, those vibra- tions add up.
The Vibration Is Significant
A 2013 study published by The Journal of Spinal Cord Medicine researched the effect of whole-body vibration (WBV) by monitoring wheelchair users for two weeks.
It defined WBV as “vibration transmitted by supporting surfaces to the entire human body.”
The findings: “All wheelchair users who participated in this study were continuously exposed to WBV levels at the seat that were within and above the health caution zone specified by ISO 2631-1 during their day-to-day activities. ... WBV exposure to wheelchair users exceeds interna- tional standards.”1
The study added, “There is evidence that seated WBV exposure is a risk factor for spinal disorders, excessive muscle fatigue, and damage to the connecting nerves.”
Vibration & Quality of Life for PWC Users
A paper presented at the 2015 RESNA conference looked closely at the impact of vibration on quality of life for power wheelchair users.
The researchers were Carmen DiGiovine, Amy Darragh, Theresa Berner, and Taylor Duncan, all with The Ohio State University Wexner Medical Center’s Assistive Technology Center. The study included four focus groups, two composed of power wheelchair users who used power chairs as their primary means of mobility, and two composed of rehab professionals (clinicians and complex rehab technology suppliers) who recom- mended and provided power wheelchairs.
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One observation was how often power chair users experience vibration. They listed more than 30 surfaces and obstacles that “caused shocks, vibrations and motion within their power wheelchairs.” Surfaces from cobblestone to cracked sidewalks were problematic.
Vibration makes power chair use both physically and mentally more taxing, consumers said.
“The surfaces and obstacles have a significant effect on their ability to travel,” the study reported. “The surfaces and obstacles have an [e]ffect on their pre-trip plan- ning, on the actual trip (e.g., lengthen trip, lose control
of wheelchair), and on post-trip activities (e.g., fatigue, repositioning in seating system). Traversing the surfaces and obstacles has an effect on the person in terms of increased pain, discomfort, numbness and apprehen- sion. The surfaces and obstacle[s] that were identified as having the largest effect were brick, truncated domes, gravel, broken-down/crumbling sidewalk, and any unan- ticipated/unexpected obstacles.”
Clinicians noted that many diagnoses can be nega- tively affected by vibration, including spinal muscular atrophy, muscular dystrophy, multiple sclerosis, ALS, spinal cord injury, cerebral palsy, spina bifida, stroke, and lower-extremity amputations.2
Tomorrow’s Power Chairs
Based on the effects of vibration on a power chair user’s positioning, function and spirit, what did the consumers in the study want the rehab industry to know?
“Future wheelchairs should focus on minimizing shock, vibration and motion,” researchers said. Consumers suggested that being able to activate/deactivate a power chair suspension on demand would be useful.
And consumers suggested that power chair designers could best learn from experiencing vibration themselves. “Engineers should live in the wheelchair,” the study
said, “in order to fully experience what it is like to use a wheelchair in the community. Furthermore, individuals with disabilities should fully participate in the design and development of wheelchairs.” m
Sources & Resources: 1 The Journal of Spinal Cord Medicine, U.S. National Library of Medicine, National Institutes of Health, July 2013, https://www.ncbi.nlm.nih. gov/pmc/articles/PMC3758533/; 2 The Effect of Whole Body Vibration on Power Wheelchair Mobility: A Focus Group, https://tinyurl.com/pwcvibration
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