Validity and Accuracy of Physical Activity Monitors for Estimating Energy Expenditure During Wheelchair Locomotion

PURPOSE: To compare energy expenditure (EE) estimates of two physical activity monitors with measured EE during wheelchair locomotion.

METHODS: Participants were fourteen individuals who used manual wheelchairs. Each participant performed five different locomotion activities in a manual wheelchair. These 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 sidewalk course that included uphill and downhill segments at the participants self-selected speed. EE was measured using a portable indirect calorimetry system (Oxycon Mobile, Viasys Healthcare). Each subject wore an Actical (AC) and a SenseWear (SW) activity monitor on the right wrist and upper arm, respectively. A repeated measures ANOVA was used to compare measured EE to the estimates from the AC and the SW. Additionally, EE estimates from a wheelchair specific prediction equation using the SW data (Hiremath and Ding, 2011) was also compared. Bland-Altman plots were used to assess the agreement between the criterion values and the predicted values.

RESULTS: A repeated measures ANOVA demonstrated a significant main effect between measured EE and estimated EE (p < 0.01). There were no significant differences between the criterion method and the AC (±9 to 25%, p > 0.05). The SW significantly overestimated EE when wheeling at 4.5 km·hr-1, 5.5 km·hr-1, 6.5 km·hr-1, and during self-paced sidewalk wheeling (+30 to 80%, p < 0.05). The Hiremath and Ding SW equation on average improved in the EE prediction during low intensity activities, but error progressively increased during higher intensity activities (+27 to 43%).

CONCLUSION: Overall, the wrist-mounted AC can accurately estimate EE (±9 to 25%) whereas the SW tends to overestimate EE during wheelchair locomotion. The wrist-mounted accelerometer is a viable option for physical activity assessment during wheelchair propulsion.