Fitbit Fitness Devices Deliver ‘Inaccurate’ Heart Rate Readings

The use of wearable devices to monitor health and fitness has come under scrutiny after it was discovered the heart rate tracking technology used in Fitbit devices delivers inaccurate readings.

The technology, known as PurePulse, was found to be as much as 23 beats per minute (bpm) off compared to the number recorded by an electrocardiogram (ECG), according to a study commissioned by law firm Lieff Cabraser, which is now conducting a class action law suit.

Inaccurate?

The study participants were hooked up to a medically-validated ECG to take an accurate reading, then were equipped with a Fitbit Charge HR on one wrist and the Fitbit Surge (pictured left) on the other.

Following a 65-minute period of exercise, heart rate readings were taken and compared to the ECG readings, with the study’s authors finding that there were significant discrepancies between the two.

“The PurePulse technology embedded in the Fitbit optical sensors does not accurately record heart rate, and is particularly unreliable during moderate to high intensity exercise,” authors Edward Jo, PhD and Brett A. Dolezal, PhD, wrote.

In their conclusion, the study said that Fitbit products had “significant limitations … for biometric monitoring during exercise” and that PurePulse technology used in the company’s heart rate monitoring devices, “is not a valid method for heart rate measurement, and cannot be used to provide a meaningful estimate of a user’s heart rate.”

TechWeekEurope has contacted Fitbit concerning the findings but has not yet received a response at the time of publication..

Many wearable devices, including the Apple Watch, have fitness features in a bid to attract consumers and professionals in the healthcare industry.

The study is not the first question raised about Fitbit’s practices. Last year, the company was hit by a lawsuit by rival Jawbone, claiming Fitbit was “systematically plundering” staff and critical trade secrets after Fitbit recruiters contacted a third of Jawbone’s employees and hired at least five people.

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