Fitness trackers, counting calories burned is wrong

Stanford University research has shown how trackers are reliable in calculating heart rate but unreliable on calories burned

Fitness trackers have often been blamed for their lack of reliability in the results shown. New research has shown that most of these devices allow you to monitor your heart rate fairly accurately but count calories burned is incorrect.

Researchers compared the results of seven different wearables applied to more than 50 different athletes. During and after physical activities, they compared data obtained with fitness trackers and that which emerged from extensive analysis with laboratory instruments. "We were pleasantly impressed with the accuracy that most of the trackers showed in calculating heart rate," said Euan Ashley, professor of cardiovascular medicine at Stanford University and co-author of the research. "At the same time, however," the professor continued, "the calculation of calories burned was a disaster."

The Research

The devices tested were in order: the Apple Watch, Basis Peak, Fitbit Surge, Microsoft Band, Mio Alpha 2, PulseOn and Samsung Gear S2. The study involved 31 women and 29 men and focused on running and exercise bike-related exercises. "At first glance it seems that the various devices in counting calories do not take into account the age, weight and gender of people, - said Ashley - and for this reason the data provided by the tracker is completely unreliable." As for the accuracy on heart rate instead the most accurate is Apple Watch with only 2% margin of error. While the worst was Samsung Gear S2 with a margin of error of 6.2%. In the calculation of calories, the worst, with 96% probability of error, was PulseOn. This discovery puts manufacturers in crisis and especially worries users who until now have focused their exercises and their diet on the information provided by these particular electronic devices.