In a paper published in January this year, researchers try to evaluate the usefulness of wrist-worn smart devices for tracking energy expenditure and heart rate. The Apple Watch Series 6, Polar Vantage V and the Fitbit Sense were used by 30 healthy male and female participants engaging in weight training, cycling, running walking and even sitting. As reference devices, the team used the Polar H10 chest strap and the MetaMax 3B.
Now, we won’t bore you with the details of the study or the methods used as they seem solid enough and instead, we will talk about the findings. The guys at Stronger by Science summarized it into a simple table that evaluates the accuracy, variability and reliability of each device.
As it turns out, all of the devices were pretty bad at tracking calories in almost all of the activities. Not only that, but the average deviation from the actual daily expenditure was unpredictable and wildly varying rendering the watches useless at tracking calories. That’s because you can’t reliably track progress even if absolute values are off. It seems that the wearables are even more inconsistent with individuals that have lower-than-average and higher-than-average energy expenditure.
The research also seems to be in line with previous ones trying to assess the same capabilities but with different wrist-worn devices.
The good news is the Apple Watch Series 6 was pretty reliable in tracking heart rate across all activities. Polar Vantage V and the Fitbit Sense wearables fluctuate depending on the exercise. Steps count also seems to be on point for all of the devices involved in the research.
The bottom line? Despite its limitations, such as the small sample size of devices and individuals, the research seems to be in line with previous ones suggesting that the commercially available smartwatches and wrist-worn fitness trackers don’t provide reliable measurements of your daily energy expenditure. Moreover, they are highly unpredictable.
Nevertheless, heart rate tracking and steps counting are features that are usually quite useful and dependable. In fact, some research suggests that smart wearables alone may introduce a positive impact on one’s fitness life. People who use smart wearables tend to increase overall activity and steps count.