Wheelchair-mounted accelerometers for measurement of physical activity

Purpose: To evaluate the validity of a wheelchair frame-mounted accelerometer for the assessment of physical activity of wheelchair users. Method: Twelve collegiate wheelchair basketball players participated in this study. The study was conducted in a modern indoor gymnasium at a university in the USA. A randomized, crossover experimental design was used to investigate accelerometer output, participant heart rate, and distance travelled. Participants performed two trials of wheeling at a combination of two different effort levels (light and moderate: Prescribed using perceived exertion) and two different modes (continuous and stop-go). Results: Accelerometer vector magnitude activity counts (VM), heart rate (HR), and distance travelled were significantly different between light and moderate effort (p < 0.01). The continuous and stop-go wheeling modes were not significantly different (p=0.37) for VM, but were significantly different (p < 0.01) for both HR and distance. Between-trial reliability of all data collapsed for the effort and mode combinations were: VM: r=0.85; HR: r=0.86; and distance: r=0.96. Conclusion: A wheelchair frame-mounted accelerometer differentiated between perceptually-prescribed low and moderate effort levels and may prove to be a valid instrument in the detection of a wheelchair users' physical activity. Implications for Rehabilitation When placed on the hip of able-bodied persons, accelerometers have been shown to be a useful tool for assessing physical activity. Current literature of wheelchair users and accelerometry includes investigations of arm-mounted, body-mounted, and wheel-mounted accelerometers. The current study investigates a wheelchair-frame mounted triaxial accelerometer's ability to detect group differences during light and moderate intensity wheeling under controlled conditions. Findings indicate that wheelchair frame-mounted accelerometers may be a useful tool for measuring a wheelchair user's daily activity patterns and estimating energy expenditure in a free living environment.