POMONA (CBSLA.com) — Researchers at Cal Poly Pomona claim Fitbit’s PurePulse is “highly inaccurate” but the makers of the device say not so fast.

Cal Poly Pomona was hired by attorneys for plaintiffs in a class-action lawsuit against the company.

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Researchers at the Pomona school tested the heart rates of 43 adults using the PurePulse.

They then hooked the same individuals up to a medical device that measures heart rate.

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The study found the Fitbit device was off by up to 20 beats per minute on average during intense workouts.

But Fitbit responded to the study with a statement that reads in part:

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“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. 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.”