Researchers have cast doubt upon the effectiveness of Fitbit's proprietary PurePulse technology to reliably gauge heart rate during periods of physical exertion.

According to newly released findings underwritten by the legal team currently seeking damages from tech giant Fitbit through class action lawsuit, the popular exercise accessory regularly miscalculated its wearer's heart rate by an average of around 19 beats per minute.

The California State Polytechnic University at Pomona study asked 43 participants to carry out an hour's worth of vigorous tasks analogous to actions portrayed within Fitbit marketing materials. While jumping rope or jogging in place, each participant wore a Fitbit, an electrocardiogram sensor, and a medical-grade Zephyr BioHarness.

Comparing results, the scientists eventually determined Fitbit not just significantly inaccurate, but unpredictably inaccurate. Different models displaying beats per minute were well above or well below concurrent measurements.

“With strong scientific reasoning,” authors Edward Jo and Brett A. Dolezal conclude, “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.”

Fitbit counterattacked with a tersely-worded condemnation of the CSPU findings. “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.”

As Fitbit representatives note, similar experiments have been overseen by institutions across the country, and the majority arrived at results either inconclusive or broadly supporting the usefulness of the device.

In the end, none of this may have any impact upon the ongoing lawsuit. Even if repeated independent investigations proved Fitbit to be plagued by fundamental systemic errors, legal observers have questioned whether the nebulous claims advertised by Fitbit's manufacturer could reasonably be construed as guaranteeing its users the precise measurement of biological data.

Shortly after the lawsuit began, Fitbit issued a press release highlighting the distinction: “The success of Fitbit products comes from empowering people to see their overall health and fitness trends over time — it's these trends that matter most in achieving their goals.”

However, despite the overwhelming success of Fitbit products — President Obama regularly shows off his Surge — health maintenance professionals have questioned for some time whether the company's devices may do more harm than good.

Users continually glancing at the screen for an artificial verification of their efforts could well be less likely to later regard physical fitness as a lifelong commitment. Conversely, gym-rats desperate to see the numbers rise may injure themselves chasing illusory results.

So long as the increasingly hostile legal maneuvers of each side are splayed across the headlines, though, suspicions over Fitbit's efficacy have led only to heightened curiosity over potential improvements.

One hotly-touted recent innovation named Chem-Phys doubles as a patch of skin and promises to revolutionize P.E. tech by cataloging not just heart beats but amounts of a chemical (lactate) thought to be produced during sustained exertion. Additional sensors recording such pertinent chem-trails as potassium and magnesium are currently being worked out.

Instant Insights /

Study questions fitness of wrist-worn activity monitor

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