Sensors heart rate are a common element of “smart” watches and fitness trackers. They are all based on the method of photoplethysmography (optical plethysmography). The accuracy of this method in comparison with electrocardiography, underlying chest heart rate monitors, is much lower.
In the United States was filed a collective lawsuit against the manufacturer of Fitbit trackers sports, who was accused of incorrectly measuring the heart rate. The plaintiffs allege that the company intentionally misled them, saying in advertising that its fitness trackers are equipped with sensors measuring heart rate with precision so that they can be used during training to monitor heart rate.
The lawsuit contains data about the research, which was attended by 43 people. For 65 minutes they performed a series of physical exercises around such as that shown in the advertisement Fitbit: fast walking, walking on stairs, running on the treadmill, ryzhky rope. Data trackers, Charge HR and Fitbit Surge were compared with the electrocardiograph. It turned out that the skew may exceed 20 beats per minute is not in favor of Fitbit products.
Fitbit PurePulse uses the term for its tracking technology, heart rate. It is based on the photoplethysmography sensor contains two LEDs and a photocell. The LEDs Shine skin with the blood vessels, while the photocell detects the change of optical density. Optical density is then converted in pulse rate.
At the conclusion of the study States that the Fitbit “will not provide useful information about the heartbeat.” The relatively low accuracy of the sensors of heart pulse activity trackers due to the technology used and there is nothing illegal. On the other hand, the producers about this their buyers are not informed, but it can already be seen as consumer fraud.
