Accepted for/Published in: JMIR mHealth and uHealth
Date Submitted: Apr 30, 2019
Open Peer Review Period: May 3, 2019 - Jun 28, 2019
Date Accepted: Jul 19, 2019
(closed for review but you can still tweet)
Accuracy in energy expenditure estimation of the multisensory wristwatch Polar Vantage during various activities
ABSTRACT
Background:
Sport watches and fitness tracker provide a feasible option of energy expenditure (EE) estimation in daily life as well as during exercise. However, todays popular wrist-worn technologies show only poor to moderate EE accuracy. Recently, the invention of optical HR measurement and the further development of accelerometers in wrist units have opened up the possibility of measuring EE.
Objective:
The aim of this study was to validate the new multisensory wristwatch Polar Vantage and its EE estimation in healthy individuals during low- to high-intensity activities against indirect calorimetry.
Methods:
Thirty volunteers (15 female; 29.5 ± 5.1 years; 1.7 ± 0.8 m; 67.5 ± 8.7 kg; VO2max of 53.4 ± 6.8 ml/min*kg) performed seven activities—ranging in intensity from sitting to playing floorball—in a semi-structured indoor environment for 10 minutes (min) each, with 2 min breaks in between. These activities were performed while wearing the Polar Vantage M wristwatch and the MetaMax 3B spirometer.
Results:
After EE estimation, mean ± standard deviations of 69.1 ± 42.7 kilocalories (kcal) and 71.4 ± 37.8 kcal per 10 min activity were reported for the MetaMax 3B and the Polar Vantage, respectively, with a strong correlation of r = .892 (P < .001). The systematic bias was 2.3 kcal (3.3%), with ± 37.8 kcal limits of agreement. The lowest mean absolute percentage errors were reported during the sitting and reading activities (9.1%), and the highest error rates during household chores (31.4%). On average, 59.5% of the mean EE values obtained by the Polar Vantage were within ± 20% of accuracy when compared to the MetaMax 3B. The activity intensity quantified by perceived exertion (odds ratio = 2.028, P < .001) and wrist circumference (odds ratio = −1.533, P = .03) predicted 29% of the error rates within the Polar Vantage.
Conclusions:
The Polar Vantage has a statistically moderate to good accuracy in EE estimation that is activity-dependent. During sitting and reading activities, the EE estimation is very good, whereas during non-steady activities that require wrist and arm movement, the EE accuracy is only moderate. However, compared with other available wrist-worn EE monitors, the Polar Vantage can be recommended, as it performs among the best.
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