Everyone’s got one nowadays, and you might have just received one as a gift this holiday season– Fitbit, Apple Watches, and the like are currently a popular trend with each and every new release boasting a better ability to more accurately track your step count, measure your heart rate, or calculate the number of calories you burned. But are they really that accurate? 

A recent study published in 2020 concluded that NONE of these wearable devices could be considered a “gold standard” for measuring step count or energy expenditure. 

Why? Let’s dive into their results. 

Step Counting

In terms of step counting, these devices produced more accurate results in controlled rather than free-living conditions. However, in both settings, the devices did frequently underestimate true step numbers. Overall, Apple, Samsung, Garmin, and Fitbit devices performed the best. 

Heart Rate

Heart rate measurements were accurately calculated by all devices in controlled conditions. In this situation, Fitbit devices often underestimated heart rate, while Apple and Garmin were the most accurate. 

Energy Expenditure

Finally, researchers determined that energy expenditure measurements from ALL devices were incredibly inaccurate, even within controlled settings. Some brands overestimated energy expenditure, including Apple devices, while others underestimated energy expenditure, like Garmin. Fitbit showed a large variation in its results, both over and underestimating. Overall, less than 10% of the brands fell within acceptable measurement limits. 

What We Learned

So, should you really count on your wearable device to keep track of your health stats?

Sure, when it comes to simply monitoring your daily step count or your heart rate during a workout, these devices do a decent job and are great for personal record keeping. But when it comes to measuring caloric expenditure, we would not recommend betting your numbers on these devices. 

*Note that Apple devices included Apple Watches which were worn on the wrist. Garmin devices only included ones that were worn on the wrist. Fitbit devices included wrist, arm, leg, and chest worn devices.

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References

1. Fuller, D., Colwell, E., Low, J., Orychock, K., Tobin, M. A., Simango, B., Buote, R., Van Heerden, D., Luan, H., Cullen, K., Slade, L., & Taylor, N. (2020). Reliability and Validity of Commercially Available Wearable Devices for Measuring Steps, Energy Expenditure, and Heart Rate: Systematic Review. JMIR mHealth and uHealth, 8(9), e18694. https://doi.org/10.2196/18694