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What does current research say about the validity of wearables?



Activity trackers (ATs) and heart rate (HR) monitors have become increasingly popular. There are lots of choices, and the selection process depends on many variables, including accuracy.

Researchers tested eight wearable devices (Apple Watch Series 2, Fitbit Blaze™, Fitbit Charge 2™, Garmin vivosmart® HR, TomTom Touch, Polar® A360, Polar® HR7 and Bose® SoundSport Pulse headphones). All eight offered HR monitoring, and all except for the Bose headphones claimed to estimate caloric expenditure. The study’s goal: to assess how accurately the devices measured HR and activity during cycling and resistance training.

Fifty subjects (28 females, aged 23 ± 3; 22 males, aged 22 ± 3) took part in both exercise modes in a randomized order, testing all eight activity trackers. The volunteers were also connected to “gold standard” devices—an electrocardiogram to measure HR and a metabolic gas analyzer to estimate caloric expenditure. Using scientifically validated statistical analysis, researchers then compared HR and (when applicable) caloric expenditure data from the wearables with those reported by the gold standard devices.

Results revealed that, for HR monitoring, Polar HR7 and Bose SoundSport Pulse headphones met the validity standard (having a mean absolute percent error value ≤10%) during both cycling and resistance training; the Apple Watch Series 2 was the most accurate during cycling; and the Bose headphones performed best during resistance training.

No devices accurately estimated caloric expenditure, which is an important point for clients who are tracking calories for fat loss.

REFERENCE: Boudreaux, B.D., et al. 2018. Validity of wearable activity monitors during cycling and resistance exercise. Medicine & Science in Sports & Exercise, 50 (3), 624–33.

Meet our experts

AFM_Author_Nunez TONY P. NUÑEZ, PHD, is an assistant professor in exercise science at Metropolitan State University of Denver. He is an active researcher and presenter in the exercise physiology and fitness field.

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