Lieff Cabraser Civil Justice Blog
New Testing Confirms Fitbit’s PurePulse™ Heart Rate Monitors “Highly Inaccurate”

FOR IMMEDIATE RELEASE−Warning: Fitbit Heart Rate Monitors Not Coming Close to “Counting Every Beat”

New Independent Study published in The Annals of Internal Medicine Confirms the Significant Inaccuracy of the Heart Rate Monitors Made by Fitbit, Self-Proclaimed “Digital Healthcare Company”

April 11, 2017–San Francisco–Researchers from the University of Wisconsin in Madison and Loras College in Dubuque, Iowa announced the results of new independent testing on a selection of wearable heart rate monitors, confirming findings in previous studies that the PurePulse™ technology used in Fitbit’s popular fitness trackers is wildly inaccurate during moderate and high-intensity exercise.

The study found that while the devices performed reasonably well while the wearer was at rest, during exercise the Fitbit trackers are off by 20-40 beats, or 12.5-25%.  That is an extremely high error rate, and potentially dangerous for users who need to keep their exercise heart rates within set ranges. “However accurate they may be at rest, the Fitbits are wildly inaccurate as heart rate monitors when worn during moderate- and high-intensity exercise, which is precisely the purpose for which Fitbit (in particular) markets them to consumers,” said Jonathan Selbin, one of the attorneys who filed a consumer protection lawsuit in 2016 on behalf of Fitbit owners who bought the devices to track their heart rates during exercise.

The University of Wisconsin study is the latest in a long line of tests confirming the inaccuracy of the Fitbit devices during exercise. Recent testing conducted at Cleveland Clinic Heart and Vascular Institute, for example, revealed that the Fitbit HR experienced a 16% error rate for heart rate during moderate treadmill exercise and “fell short” of the mark for consumers. A study at California State Polytechnic University, Pomona also found very significant inaccuracies in the Fitbit heart rate devices, and concluded that “at moderate to high exercise intensities, the average difference between the Fitbit devices and the ECG was approximately 20 beats per minute, well beyond any reasonable or expected margin of error.”

This data corresponds closely with results of testing conducted in February 2016 by researchers at Ball State University in Indiana. They too found that the Fitbit heart rate devices were off by “20 or 30 beats per minute,” a margin of error they concluded was unacceptably high and “dangerous – especially for people at high risk of heart disease.” As that report put it, “The box for the Fitbit Charge HR says ‘every beat counts,’ but despite what the package says, the tracking device inside missed lots of them.”

These very significant error rates are at odds with Fitbit’s extensive national marketing campaign, in which the company claims the products will “count . . . every beat” and enable users to “know your heart.”

As the Fitbit devices are aggressively marketed to and for exercisers rather than those sitting quietly at rest, the performance deficiencies are a real problem, and Fitbit’s wearable trackers can provide flatly inaccurate information that can be dangerous to some users.

Although Fitbit has attempted to dismiss the studies with claims that the heart rate trackers are not “medical devices,” Selbin and others point out that Fitbit “claims to be a ‘Digital Healthcare Company’ and is actively trying to get corporations and insurers to make health care decisions based upon data they collect.” Fitbit knows its customers rely on the heart rate monitors to deliver accurate data, and promotes them for that very purpose in advertising and marketing. In an interview on CNBC, in fact, Fitbit CEO James Park touted Fitbit as not just a manufacturer of fitness trackers, but as a “digital healthcare company.”

Meanwhile, in an order issued in October 2016 in a different class action against Fitbit over alleged securities fraud arising from its sale of the Fitbit heart rate monitors, a San Francisco federal court cited three confidential witnesses from within Fitbit who state that the company knew about the inaccuracy of its heart rate monitors since at least 2014. According to the order, one of the confidential witnesses reported that Fitbit’s own internal studies found the “heart-rate monitoring devices to be highly inaccurate, particularly during vigorous exercise.”

Fitbit claims to have conducted “extensive internal studies,” to validate its heart rate monitors but refused to release the results of those studies and conspicuously stopped short of claiming that they support its claims that the heart rate monitors are accurate. As shown above, a plethora of rigorous and independent studies show that they are not.

Study after study reveals the marked inaccuracies in Fitbit’s wearable trackers, and if the confidential witnesses are correct, Fitbit has long known that its heart rate monitors do not work as promised and hid that fact from its customers and the public for years.

Consumer Protection Attorneys at Lieff Cabraser

On January 5, 2016, attorneys at Lieff Cabraser, along with their co-counsel, filed a class action complaint on behalf of consumers seeking redress for Fitbit’s deceptive and misleading representations about its heart rate monitor products. The consumers claim that, as all the data demonstrates, Fitbit’s heart rate monitors cannot accurately or meaningfully record heart rates during high-intensity exercise, precisely what Fitbit advertised them for.

The consumers also claim that Fitbit fraudulently tried to shield itself from liability for these defective products by tricking consumers into agreeing to an arbitration agreement, which the consumers argue should not be enforced.

If you purchased a Fitbit heart rate monitor (Fitbit Charge HR, Charge 2, Blaze, and Surge), we invite you to visit our Fitbit heart rate monitor lawsuit page to contact a consumer attorney at Lieff Cabraser. We welcome the opportunity to learn of your experiences with your Fitbit heart rate monitor and to answer any questions you may have about your legal rights.

About Lieff Cabraser and Counsel

Recognized as “one of the nation’s premier plaintiffs’ firms” by The American Lawyer, Lieff Cabraser Heimann & Bernstein, LLP, has successfully litigated and settled hundreds of class action lawsuits in federal and state courts, including dozens of cases requiring manufacturers to remedy a defect, extend warranties, and refund to purchasers the cost of repairing the defective product. It has recovered billions of dollars for consumers in such cases. With seventy attorneys in offices in San Francisco, New York, Nashville, and Seattle, we are among the largest law firms in the United States that represent only plaintiffs.

The consumer plaintiffs are also represented by Robert Klonoff and Levi & Korsinsky LLP.

Contact for media inquiries:

Lieff Cabraser Heimann & Bernstein, LLP
Jonathan D. Selbin