Fitness trackers such as Fitbit are great when it comes to measuring your heart rate but it appears that they are no so accurate when it comes to counting calories burned.
Scientists have advised users to monitor their own exercise and health rather than rely on information provided by devices such as Fitbit and the Apple Watch.
The team tested seven devices in total with the Apple Watch performing best and Samsung Gear S2 performing worst.
All seven were within 5% margin of accuracy when it came to heart rate monitoring – the team were aiming for 10% so all excelled.
However, none of the devices measured the number of calories burned accurately. The Samsung Gear S2 was off by 93% and the Apple Watch, which was the most accurate overall, was off by 27%.
Results from the watches were compared to results from two ‘gold standard’ medical instruments.
Professor Euan Ashley of Stanford University said that manufacturers do test the accuracy of the devices “but consumer devices aren’t held to the same standards as medical-grade devices, and it’s hard for doctors to know what to make of heart rate data and other data from a patient’s wearable device,’ he added.
Using the data, Professor Ashley suggested users took home that the heart rate tracker was accurate but judging your diet based on the information provided by the device was not a good idea.
The full findings were published in the Journal of Personalized Medicine.