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Date of Award
Bachelor of Science (BS)
Department of Kinesiology
Trent A. Hargens
Christopher Joseph Womack
Elizabeth S. Edwards
Purpose Physical activity monitors have become popular among the general public to monitor steps, floors climbed, active minutes, and energy expenditure (EE). While there is evidence to support that these devices are accurate in counting steps, there is limited and inconclusive research regarding how accurate they are in measuring EE. This study aimed to test the accuracy of a newer commercial physical activity monitor, the Fitbit Charge (FC), in reporting EE compared to a research-grade accelerometer (GT3X), and indirect calorimetry (IC) while walking on a treadmill with and without incline.
Methods 30 subjects (22 female and 8 male) walked on a treadmill for 4 five-minute stages: 2 mph with 0% grade, 2 mph with 5% grade, 3 mph with 0% grade, and 3 mph with 5% grade. IC was used to measure EE, and subjects wore the FC on their non-dominant wrist and the GT3X on their right hip.
Results Analysis showed significant main effect for device and stage, and a significant interaction effect between device and stage. EE for FC was higher (26.22 ± 5.57, 32.10 ± 4.79, 35.39 ± 6.97, and 36.64 ± 6.64 kcals) compared to IC (14.27 ± 3.51, 19.97 ± 4.05, 21.92 ± 4.04, and 28.37 ± 5.78 kcals) and to the GT3X (8.20 ± 3.81, 10.47 ± 7.99, 27.07 ± 10.77, and 27.89 ± 10.64 kcals) for all stages. EE for GT3X was also significantly (P < 0.001) different from IC. FC significantly (P < 0.001) overestimated mean total EE (130.36 ± 4.19 kcals) compared to IC (83.79 ± 3.08 kcals) and GT3X (73.25 ± 5.26 kcals).
Conclusion FC overestimates EE regardless of incline compared to EC and GT3X.
Bickel, Kaitlin M., "The effect of incline on caloric expenditure measured by a wrist-worn commercial activity monitor" (2017). Senior Honors Projects, 2010-current. 318.