Fitness trackers display unreliable statistics, research finds

Wearables constitute one of the fastest-growing consumer sectors, with millions of people buying them in hopes their health will improve or they will lose weight faster. But maybe we shouldn’t base our entire lives on the statistics provided by a wireless tracker, research finds.

A group of researchers from Stanford University conducted an experiment on seven consumer devices to determine how effective fitness trackers actually are in comparison with high-tech measurements used in their lab.

An electrocardiograph (ECG) measured heart rate and indirect calorimetry was used to measure calories burnt. Overall, they found these gadgets are quite accurate at monitoring heart rate, showing a small percentage of errors, but when it comes to calorie estimation, the figures were not that accurate.

“We were pleasantly surprised at how well the heart rate did – under many circumstances for most of the devices, they actually did really quite well,” said Euan Ashley, professor of cardiovascular medicine at Stanford University and co-author of the research.

“At the same time we were unpleasantly surprised at how poor the calorie estimates were for the devices – they were really all over the map.”

The tests on the Apple Watch, Basis Peak, Fitbit Surge, Microsoft Band, Mio Alpha 2, PulseOn, and Samsung Gear S2 involved 60 male and female volunteers who wore the trackers while walking, running and cycling.

“When you consider that people are using these estimates to essentially make lifestyle decisions like what they are going to eat for lunch then I think that is something that is worth knowing and people should know to take these estimates with more than a pinch of salt,” said Ashley.

The findings were published this week in the Journal of Personalized Medicine.