Fitbit fit for purpose? Heart rate lawsuit doesn’t think so

Leading wearable fitness tracking company Fitbit has found itself on the receiving end of a damning lawsuit claiming it fails to accurately measure users' heart rate during periods of high intensity exercise.

A class action claim filed in January in the US said that the product failed to accurately gauge user’s activity. It said: “[Fitbits] do not and cannot consistently and accurately record wearers' heart rates during the intense physical activity for which Fitbit expressly markets them.”

It’s marketing includes "Every beat counts" and "Know your heart" meaning measurement accuracy is inherent in its product.

One claimant found that the Fitbit dropped as much as 25bpm below his independently measured rate from his doctor. He was informed not to raise his HR above 160bpm during exercise for medical reasons.

This funnels into the claim, it states: “The defect in the PurePulse Trackers presents a safety hazard because class members’ could jeopardise their health by relying on the inaccurate heart rate readings and potentially achieving dangerous heart rates."

Fitbit’s Charge HR wristband and Surge fitness carry a PurePulse tracker which uses LEDs to measure blood flow volume, an unorthodox way of measuring heart beats.

Bringing into disrepute Fitbit's system were California State Polytechnic University researchers, funded by claimants. Forty three healthy patients were monitored, finding that higher activity levels skewed the readings further, on average off by as much as 17bpm.

Fitbit rubbished the study however claiming it was “biased, baseless, and nothing more than an attempt to extract a payout from Fitbit,” adding “It lacks scientific rigour and is the product of flawed methodology.”

The case continues.

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