Fitbit heart rate tracking is dangerously inaccurate, lawsuit claims
Claims from fitness tracking company Fitbit that its wristbands can accurately monitor owners' heart rates are wildly and in some cases dangerously misleading, according to a lawsuit.
Fitbit owners from several US states claim that despite the company's products purporting to accurately measure heart rates, Fitbits "do not and cannot consistently and accurately record wearers' heart rates during the intense physical activity for which Fitbit expressly markets them".
One claimant in the class-action lawsuit says that while her personal trainer measured her heart rate at 160 beats per minute, her Fitbit Charge HR recorded a rate of 82 bpm. Another who said his doctor had told him not to exceed 160 bpm found that his Fitbit Surge device was as much as 25 bpm below what other trackers said.
Fitbit, the world's bestselling fitness tracker manufacturer, sells two products that claim to monitor users' heart rates, as well as tracking steps, calories burned and sleep quality.
The Charge HR wristband and Surge fitness watch both have a "PurePulse" sensor on the underside of the tracker. Rather than actually detecting heartbeats, it uses LEDs that reflect onto the skin to detect changes in blood volume, with software then working out the difference.
Fitbit has marketed the products with slogans such as "Every beat counts" and "Know your heart", and its website claims to allow owners to "check real time heart rate".
The plaintiffs claim that Fitbits consistently undershoot actual heart rates however, and are claiming damages. "The defect in the PurePulse Trackers presents a safety hazard because Class members’ could jeopardize their health by relying on the inaccurate heart rate readings and potentially achieving dangerous heart rates," the lawsuit says.
In response, Fitbit said that while its trackers provide better heart rate data than measures such as gym equipment, they are not intended to be scientific.
"We do not believe this case has merit. Fitbit stands behind our heart rate technology and strongly disagrees with the statements made in the complaint and plans to vigorously defend the lawsuit," the company said.
"Fitbit is committed to making the best clip and wrist-based activity trackers on the market. Our team has performed and continues to perform internal studies to validate our products’ performance.
"PurePulse provides better overall heart rate tracking than cardio machines at the gym, as it tracks your heart rate continuously – even while you’re not at the gym or working out. But it’s also important to note that Fitbit trackers are designed to provide meaningful data to our users to help them reach their health and fitness goals, and are not intended to be scientific or medical devices.”
The lawsuit is the second blow to Fitbit in a week, after its new smartwatch was met with a frosty reception by investors. Shares fell by more than 10 per cent on Tuesday after the company unveiled the Fitbit Blaze , which also has the PurePulse technology and includes features such as smartphone notifications on the wrist.