Accuracy of Consumer Monitors for Estimating Energy Expenditure and Activity Type

INTRODUCTIONIncreasing use of consumer-based physical activity (PA) monitors necessitates that they are validated against criterion measures. Thus, the purpose of this study was to examine the accuracy of three consumer-based PA monitors for estimating energy expenditure (EE) and PA type during simulated free-living activities. METHODSTwenty-eight participants (mean ± SDage, 25.5 ± 3.7 yr; body mass index, 24.9 ± 2.6 kg·m) completed 11 activities ranging from sedentary behaviors to vigorous intensities. Simultaneous measurements were made with an Oxycon portable calorimeter (criterion), a Basis Peak and Garmin Vivofit on the nondominant wrist, and three Withings Pulse devices (right hip, shirt collar, dominant wrist). Repeated-measures ANOVA were used to examine differences between measured and predicted EE. Intraclass correlation coefficients were calculated to determine reliability of EE predictions between Withings placements. Paired samples t tests were used to determine mean differences between observed minutes and Basis Peak predictions during walking, running, and cycling. RESULTSOn average, the Basis Peak was within 8% of measured EE for the entire PA routine (P > 0.05); however, there were large individual errors (95% prediction interval, −290.4 to +233.1 kcal). All other devices were significantly different from measured EE for the entire PA routine (P < 0.05). For activity types, Basis Peak correctly identified ≥92% of actual minutes spent walking and running (P > 0.05), and 40.4% and 0% of overground and stationary cycling minutes, respectively (P < 0.001). CONCLUSIONSThe Basis Peak was the only device that did not significantly differ from measured EE; however, it also had the largest individual errors. Additionally, the Basis Peak accurately predicted minutes spent walking and running, but not cycling.