Validity of Caloric Expenditure Measured from a Wheelchair User Smartwatch

The objective of this study was to investigate the validity of measured caloric expenditure from a fitness smartwatch designed to measured values in wheelchair users against criterion values from a portable metabolic system. 15 wheelchair users and 15 able-bodied participants completed multiple tasks; wheelchair treadmill routine at 30, 45, and 60 strokes per minute, arm cycle ergometry at 45, 60, and 80 revolutions per minute, and arm cycle ergometry VO₂Peak test. There were no interactions for device or task and group (wheelchair users vs. able bodied, p=0.375-0.944) therefore results were pooled across groups for all measures. The smartwatch exhibited poor to moderate caloric expenditure association during wheelchair treadmill routine (ICC<0.39) and arm cycle ergometry (ICC<0.541). Smartwatch underestimated caloric expenditure during the wheelchair treadmill task (Mean differences (Limits of Agreement)) (-2.11 (-8.19-3.96), -3.68 (-12.64-5.28), and -4.51 (-15.05-6.02)) and overestimated during the arm cycle ergometry task (0.89 (-3.10-4.88), 3.40 (-0.31-7.12), and 2.81 (-1.71-7.32)). The smartwatch is currently not well suited to calculate caloric expenditure when performing exercise tasks on a wheelchair treadmill and arm cycle ergometry.