- Researchers at California State Polytechnic University have shown in a new study that the PurePulse heart rate monitors in the FitBit Surge and Charge HR have an "extremely weak correlation" with actual users' heart rates when measured by an electrocardiogram (ECG), and "highly inaccurate during elevated physical activity."
- Results showed the average difference between the Fitbit and the ECG was approximately 20 beats per minute, which is considered beyond any reasonable or expected margin of error.
- Fitbit announced earlier this month a parternship with Center for Democracy & Technology to develop research and privacy guidelines for the wearables industry.
The study included 43 individual tested for 65 minutes during various activities such as jogging, stair climbing, jumping rope, etc. Each person wore a Fitbit on different wrists while exercising and their heart rates were compared against a time-synchronized ECG.
Lieff, Cabraser, Heimann & Bernstein, which filed a fraud class action lawsuit in January against Fitbit, regarding complaints that the devices' heart rate monitors fail to accurately measure user heart rates, commissioned the study.
Athletes use heart rate monitoring to reach or not exceed specific heart rates and inaccurate heart rate reporting can have serious health consequences.
Consumers complained online that the Fitbit heart rate monitors were providing unreliable heart rate readers when users were exercising, according to a report from the Lieff Cabraser Civil Justice Blog.
The study researchers concluded that the PurePulse technology in the Fitbit'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."
In April, a Fitbit detected unusual heartbeats in a woman, who later found out she was pregnant.