This article looks at the accuracy of watch-based heart rate monitors
What’s the deal?
Sports watches and trackers are more popular than ever. Most have the ability to track heart rate, but how accurate are they?
What did they do?
50 volunteers had their heart rate accurately monitored by electrocardiogram (ECG) whilst exercising either on a treadmill, an exercise bike, or an elliptical machine. Heart rate was also monitored by a Polar H7 chest strap, Scosche Rhythm+, Apple Watch, Fitbit Blaze, Garmin FR235, or TomTom Spark Cardio and all values were compared to the ECG for accuracy.
What happened?
Overall, the Polar H7 was the most accurate heart rate monitor, with near 100% agreement with the ECG across all exercises. The Apple Watch was not too far behind for running and cycling. The TomTom and Garmin were less accurate but still good, but the Scosche and Fitbit were much less reliable. Notably, the Fitbit was very inaccurate during cycling, and only the Polar H7 could accurately track heart rate on the elliptical machine.
What can you tell me about the people?
Participants were aged between 18-64 years old, with an average age of 38. Roughly half were female. The average BMI was 25, which is in the upper normal/ lower overweight category. All participants were free from heart or lung disease.
What else should I know?
The heart produces an electrical signal each time it beats and this signal is detected by an ECG, making it very accurate. The Polar H7 was the most accurate device because it also uses this technology. Wrist-based monitors and smartwatches are more comfortable to wear, but use optical measurements (i.e. a light shines into the skin to detect blood flow and therefore heart rate), which are less accurate than electrical measurements.
What will I do differently?
I used to have a Garmin FR235 and I loved it. I’m currently on the verge of purchasing a chest strap monitor as I’m hoping to venture into heart rate-based training and need something as accurate as possible!
Acknowledgements
This research was published in August 2017 by S Gillinov and colleagues from the Cleveland Clinic, Cleveland, OH, USA.
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Abstract Athlete 