Your favorite heart rate technology may not be as accurate as you would hope.
Fitbit currently has three class action lawsuits filed against them claiming that their products are “highly inaccurate”. Researchers at the California State Polytechnic University, Pomona conducted a study that tested the accuracy of both the Fitbit Surge and the Fitbit Charge HR.
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Both of the Fitbit monitors were worn on each wrist of the 43 adults who were tested during the study. Each subject was also hooked up to a BioHarness (a chest-worn heart rate monitor), which was connected to an electrocardiogram (ECG). The BioHarness was used to record the beats per minute (bpm) as well to compare its results with the Fitbits.
The moderate to high intensity work out provided by the subjects included a self-paced outdoor jog, jump roping, treadmill running and stair climbing. By the end of the exercises, it was found that the bpm recorded by the ECG differed from the Charge HR by an average of 15.5 bpm and the Surge by an average of 22.8 bpm. These numbers combined show that the PurePulse Tracker technology used in Fitbit reads an average of 19.2 bpm off of the average ECG reading.
The report states “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.”
Since the study was conducted, Fitbit issued a statement in response:
“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 the 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.
Consumer Reports independently tested the heart rate accuracy of the Charge HR and Surge after the initial lawsuit was filed in January and gave both products an “excellent” rating. We stand behind our heart-rate monitoring technology and all our products, and continue to believe the plaintiffs’ allegations do not have any merit. We are vigorously defending against these claims, and will resist any attempts by the plaintiffs’ lawyers to leverage a settlement with misleading tactics and false claims of scientific evidence.
While the Fitbit technical specifications does mention that they don’t claim 100% accuracy and it is specified to “track” your workout rather than “measure”, the website does promise that you can “check real-time heart rate” and “use simplified heart rate zones to tailor your workouts on the spot”.