UBC Theses and Dissertations
Wheelchair vibration, whole body vibration and spasticity : a study of the influence of wheel design on wheelchair vibration and whole body vibration as a trigger of muscle spasms in populations with spinal cord injury. Messenberg, Allon
INTRODUCTION: The majority of individuals with chronic spinal cord injury (SCI) experience spasticity, which can often impair function and degrade quality of life. Reports by individuals with SCI suggest that whole body vibration (WBV), as can occur while riding wheelchairs, may trigger spasticity. OBJECTIVES: 1) Examine the influence of wheel design on wheelchair vibration. 2) Develop a system allowing exposure of individuals with SCI to WBV and analysis of muscle activity to identify spasticity. METHODS: 1) A wheelchair wheel comparison study: Vibration acceleration and frequency content produced by wheelchairs equipped with 2 different wheel designs (steel spoked and composite material spoked) were compared as: 1a) 13 subjects with SCI wheeled through an obstacle course simulating a wheelchair user's daily activities 1b) 22 non-SCI subjects wheeled down a ramp and over a vibration inducing obstacle. Vibration acceleration was recorded using 2 accelerometers mounted on the wheelchairs' main axle and footrest. The influence of wheelchair vibration on spasticity was assessed using questionnaires, completed by the SCI subjects. 2) A controlled whole body vibration (CWBV) pilot study: 2 SCI subjects were exposed to 7-12 WBV sessions. Each exposure consisted of a single frequency, lasted 20 seconds, and was repeated on 2 separate days. The WBV was applied using an electrodynamic shaker and the subjects' leg muscles' activity was recorded using an electromyography (EMG) system. Muscle spasms were identified by calculating the ratio between periods of increased muscle activity and the period before exposure to vibration. RESULTS: No statistically significant differences (p=0.05) were found in wheelchair vibration acceleration or frequency content between the 2 tested wheel designs and no clear correlation between wheelchair vibration and spasticity was apparent. The CWBV system was able to apply vibration (-+0.5 Hz, -+0.001 g) and record muscle activity (-+7 mV). The CWBV exposures produced several muscle responses that were considered to be spasms. CONCLUSIONS: The tested composite material spoked wheels do not differ, in vibration performance, from steel spoked wheels. The developed CWBV apparatus appears suitable for studying muscle activity in response to WBV.
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