The activity tracker Fitbit is marketed as a device that can help monitor things such as your heart rate to better improve your lifestyle, but according to a new study, Fitbit might not be as accurate as advertised.
The study, which was conducted by researchers at California State Polytechnic University, Pomona, was designed to test the accuracy of the heart rate monitoring technology – PurePulse – in fitness trackers manufactured by Fitbit, Inc.
Both the Fitbit Charge HR and the Fitbit Surge were tested by comparing hundreds of thousands of heart rate readings to a time-synced electrocardiogram.
The results of the study, in which participants’ heart rates were simultaneously measured by a Fitbit on each wrist, found that the PurePulse heart rate monitors on the two Fitbit models tested – the Surge and the Charge HR – can be off by up to 20 beats per minute. The study also found inconsistencies between the two devices, and at times, the device failed to record a heartbeat at all.
Between the two Fitbit models, the study found a greater discrepancy with the Surge than with the Charge HR.
In order to get a fair reading, researchers asked 43 adults to participate in different levels of activity throughout a 65-minute session, from jogging to jump-roping to treadmill running. In the end, the results showed that, the more intense the workout, the greater the margin of error.
“The PurePulse Trackers do not accurately measure a user’s heart rate, particularly during moderate to high intensity exercise, and cannot be used to provide a meaningful estimate of a user’s heart rate,” the researchers wrote.
According to Gizmodo, the study was used in an amended complaint in a class action lawsuit filed against the company by several Fitbit customers who claimed that some trackers didn’t accurately measure heart rates during exercise. And while this skews the results a bit due to bias, this is not the first investigation on Fitbit accuracy.
In February, Indiana news station WTHR manually tested six activity trackers including the Fitbit Charge HR, the Fitbit Zip, the Jawbone UP3, the iFit Vue, and the Misfit Flash. In a similar fashion, Ball State University’s Human Performance Laboratory asked volunteers to participate in a variety of activities such as walking, running, climbing stairs, sweeping, and typing.
“Most people spend the majority of their day sedentary, sitting at a desk writing or typing or reading on a computer, so having an idea how the monitors work during those activities is really important,” Dr. Alex Montoye said. “And a lot of people spend at least part of their day doing lifestyle or chore activities. Light intensity activities like that do have health benefits we want to track and be aware of.”
Ultimately, the WTHR investigation also found that there was a 20 beat per minute inaccuracy in the fitness trackers.
Fitbit recently issued a statement in response to the claims stated by the study and the lawsuit.
See the full statement below.
“What the plaintiffs’ attorneys call a ‘study’ is biased, baseless, and nothing more than an attempt to extract a payout from Fitbit. It lacks scientific rigor and is the product of flawed methodology. It was paid for by plaintiffs’ lawyers who are suing Fitbit, and was conducted with a consumer-grade electrocardiogram – not a true clinical device, as implied by the plaintiffs’ lawyers. Furthermore, there is no evidence the device used in the purported ‘study’ was tested for accuracy.
Fitbit’s research team rigorously researched and developed PurePulse technology for three years prior to introducing it to market and continues to conduct extensive internal studies to test the features of our products. Fitbit Charge HR is the #1 selling fitness tracker on the market, and is embraced by millions of consumers around the globe.”
[Photo by Eric Thayer/Getty Images]