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Int J Environ Res Public Health. 2019 Aug 22;16(17). pii: E3037. doi: 10.3390/ijerph16173037.

Validity of Wrist-Worn Activity Trackers for Estimating VO2max and Energy Expenditure.

Author information

1
Professorship of Sport Equipment and Materials, Department of Mechanical Engineering, Technical University of Munich, Boltzmannstraße 15, D-85747 Garching, Germany. stefanie.passler@tum.de.
2
Professorship of Sport Equipment and Materials, Department of Mechanical Engineering, Technical University of Munich, Boltzmannstraße 15, D-85747 Garching, Germany.

Abstract

Activity trackers are a simple and mostly low-priced method to capture physiological parameters. Despite the high number of wrist-worn devices, there is a lack of scientific validation. The purpose of this study was to assess whether the activity trackers represent a valid alternative to gold-standard methods in terms of estimating energy expenditure (EE) and maximum oxygen uptake (VO2max). Twenty-four healthy subjects participated in this study. In total, five commercially available wrist-worn devices were tested with regard to their validity of EE and/or VO2max. Estimated values were compared with indirect calorimetry. Validity of the activity trackers was determined by paired sample t-tests, mean absolute percentage errors (MAPE), Intraclass Correlation Coefficient, and Bland-Altman plots. Within the tested devices, differences in scattering in VO2max and EE could be observed. This results in a MAPE > 10% for all evaluations, except for the VO2max-estimation of the Garmin Forerunner 920XT (7.3%). The latter significantly underestimates the VO2max (t(23) = -2.37, p = 0.027), whereas the Garmin Vivosmart HR significantly overestimates the EE (t(23) = 2.44, p = 0.023). The tested devices did not show valid results concerning the estimation of VO2max and EE. Hence, the current wrist-worn activity trackers are most likely not accurate enough to be used for neither purposes in sports, nor in health care applications.

KEYWORDS:

accuracy; consumer wearable devices; fitness trackers; monitoring; physical activity; sports watches; validation

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