Fitbit heart rate trackers are "highly inaccurate," according to a study conducted as part of a class-action lawsuit against the company.
Researchers at California State Polytechnic University compared the heart rate measurements of Fitbit's PurePulse Trackers to those of an electrocardiogram and found that the Fitbit monitors were off by 20 beats per minute, on average, during exercise,
CNBC reported.
"Fitbit PurePulse Trackers do not provide a valid measure of the users’ heart rate and cannot be used to provide a meaningful estimate of a user’s heart rate, particularly during moderate to high intensity exercise," noted the study, which was commissioned and
posted online by the law firm Lieff Cabraser Heimann & Bernstein LLP, which is behind the class-action lawsuit.
The study monitored 43 healthy adults wearing Fitbit's Surge watches and Charge HR bands. They were hooked up to a BioHarness device while performing exercises such as jump roping, treadmill running, outdoor jogging, and stair climbing.
Fitbit issued a statement in response, calling the study "biased, baseless, and nothing more than an attempt to extract a payout from Fitbit,"
Gizmodo reported.
The company said its PurePulse technology was "rigorously researched and developed" for three years before being introduced to the market.
"The [Fitbits] give a pretty decent ballpark estimate of activity levels, but these are difficult elements to measure perfectly," Alex Montoye, an assistant professor of clinical exercise physiology at Ball State University,
told CNN. Montoye is not involved in the lawsuit.
Jonathan Selbin, one of the lawyers who filed the lawsuit, said the company's advertising claims are misleading, CNN reported. The lawsuit alleges fraud and misrepresentation.
"If they had just been honest and said it can give you a ballpark figure most of the time, or if the marketing emphasized that you can use these when you are aspiring to be healthier, that would have been OK, but that's not how they market it, and they charge a premium for it," he said.
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