Physical Activity Assessment in Wheelchair Users

Purpose: To examine the relationship between hand rim propulsion power and energy expenditure during wheelchair locomotion. Methods: Fourteen individuals who used manual wheelchairs were included in this study. Each participant performed five different locomotion activities in a wheelchair with a PowerTap hub built into the rear wheel. The activities included wheeling on a level surface that elicited a low rolling resistance at three different speeds (4.5, 5.5, and 6.5 km∙hr^-1), wheeling on a rubberized 400m track that elicited a higher rolling resistance at one speed (5.5 km∙hr^-1), and wheeling on a sidewalk course that included uphill and downhill segments at their self-selected speed. Energy expenditure was measured using a portable indirect calorimetry system. In addition, each subject wore an Actical and a SenseWear activity monitor on the right wrist and upper arm, respectively. Stepwise, linear regression was performed to predict energy expenditure from power output variables. A repeated measures ANOVA was used to compare the measured energy expenditure to the estimates from the power models, the Actical, and the SenseWear. Bland-Altman plots were used to assess the agreement between the criterion values and the predicted values. Results: The relationship between energy expenditure and power was significantly correlated (r = 0.694, p < 0.001). Stepwise, linear regression analysis yielded three significant prediction models utilizing measured power; measured power and speed; and measured power, speed, and heart rate. A repeated measures ANOVA demonstrated a significant main effect between measured energy expenditure and estimated energy expenditure (p < 0.01). There were no significant differences between the criterion method and the power models or the Actical. The SenseWear significantly overestimated energy expenditure when wheeling at 4.5 km·hr^-1, 5.5 km·hr^-1, 6.5 km·hr^-1, and during self-paced sidewalk wheeling (p < 0.05). Conclusion: Energy expenditure can be accurately and precisely estimated based on wheelchair propulsion power. These results indicate that wheelchair power could be used as a method to assess physical activity in people who use wheelchairs.