A new study from Stanford University published in the Journal of Personalized Medicine evaluated the accuracy of seven fitness trackers on the market: Apple Watch, Fitbit Surge, Samsung Gear S2, Microsoft Band, Mio Alpha 2, Basis Peak, and PulseOn.
60 healthy participants wore the wrist watches or bands while sitting, walking, running, and biking while also having continuous cardiac monitoring and indirect calorimetry to measure metabolic rate. Results showed fairly accurate measurements of heart rate, on average within 5% of the gold standard 12-lead ECG. Apple Watch had the greatest accuracy with an average error of 2.0% and Samsung Gear S2 had the lowest accuracy with an average error of 6.8% from the gold standard.
Unfortunately none of the devices accurately measured calorie expenditure. The most accurate device, Fitbit Surge, was off by 27% on average, and the least accurate device, PulseOn, was off by 93% on average. Researches caution use of fitness trackers for assessing calorie expenditure and encourage greater transparency from companies to validate data.
Wearable technology, such as fitness trackers, do a great job motivating people to get moving, stay mindful of their goals, and foster healthier habits throughout the day. This study highlights the benefit fitness trackers have on measuring heart rate within a generally acceptable range of error. Unfortunately there are some limitations and fitness trackers should not be relied on for accurate calorie expenditure at this time.
If you have been tracking exercise on your fitness device and considering that…cheeseburger/glass of wine/ice cream treat at the end of the day you might want to reconsider. While everything in moderation is good...if it seems too good to be true it probably is.