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Most of us love a good fitness tracker – we’re pretty faithful at taking our Fitbit with us when we go out for a run or a walk. And of course, there’s nothing better than seeing how many calories you’ve burnt off when you’re finished exercising!
But according to a new study, most fitness trackers out there actually aren’t that good at measuring calories burned – although you can rely on them to tell you your heart rate.
Stanford University researchers used a study of 60 volunteers to test 7 devices. During the study, the volunteers were asked to walk, run and cycle, and found that six out of seven devices were good at accurately measuring heart rate, but came up short when it came to keeping track of energy used up.
The study measured the Apple Watch, Fitbit Surge, Basis Peak, Microsoft Band, PulseOn and MIP Alpha 2, and the Samsung Gear S2.
All of the devices were found to have an error rate of over 20% when compared to the actual amount of calories burned. In comparison, when it came to measuring heart rate, six of the devices’ error rates were under 5%.
Dr Euan Ashley, co-author of the study from the department of cardiovascular medicine at Stanford University, says that people need to be aware that their trackers may well not be as accurate as we’re always lead to think.
He said, “People need to know that on energy expenditure they give rough estimates.
“If you go to the gym, and you think you’ve lost 400 calories, then you might feel you’ve got 400 calories to play with,”
He then warned that people may be basing their diets on how many calories they believe they’d burnt off, so were more likely to see unsatisfactory results if their fitness trackers were saying they’d burned off more calories than they really had.
Finally, he admitted that the right technology is just “not quite there yet”
We guess we’ll be taking a lot more care with our fitness trackers from now on…