Development and validation of a physical activity monitor for use on a wheelchair
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Date
2010-09-21Author
Coulter, Elaine H.
Dall, P. M.
Rochester, L.
Hasler, J. P.
Granat, M. H.
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Coulter, E., Dall, P., Rochester, L., Hasler, J. & Granat, M. (2010) Development and validation of a physical activity monitor for use on a wheelchair, Spinal Cord, vol. 49, , pp. 445-450,
Abstract
Study design: Keeping physically active is important for people who mobilize using a wheelchair.
However, current tools to measure physical activity in the wheelchair are either not validated or limited
in their application. The purpose of this study was to develop and validate a monitoring system to
measure wheelchair movement.
Methods: The system developed consisted of a tri-axial accelerometer placed on the wheel of a
wheelchair and an analysis algorithm to interpret the acceleration signals. The two accelerometer
outputs in the plane of the wheel were used to calculate the angle of the wheel. From this, outcome
measures of wheel revolutions, absolute angle and duration of movement were derived and the
direction of movement (forwards or backwards) could be distinguished. Concurrent validity was
assessed in comparison with video analysis in 14 people with spinal cord injury using their wheelchair on
an indoor track and outdoor wheelchair skills course. Validity was assessed using intraclass correlation
coefficients (ICC(2,1)) and Bland-Altman plots.
Results: The monitoring system demonstrated excellent validity for wheel revolutions, absolute angle
and duration of movement (ICC(2,1)40.999, 0.999, 0.981, respectively) in both manual and powered
wheelchairs, when the wheelchair was propelled forwards and backwards, and for movements of
various durations.
Conclusion: This study has found this monitoring system to be an accurate and objective tool
for measuring detailed information on wheelchair movement and manoeuvring regardless of the
propulsion technique, direction and speed.