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Fitbit Charge 4 Fitness Tracker – Heart Rate Monitoring

Fitibit’s Charge 4 is a fitness tracker that is trusted for its accurate monitoring data. Fitbit has had a nearly foolproof reputation in terms of reliable data recording for fitness activities such as running, brisk walking and other sports activities.

At $149, the Charge 4 is more expensive when you compare against the Mi Band 6. It is even more expensive than the Oppo’s fitness tracker. Infact, the Charge 4 is definitely more expensive that any Chinese manufactured fitness tracker. You could put Mi, Oppo and Oneplus to the list of Chinese manufactured fitness trackers. But, the premium can be justified in terms of better accuracy of heart rate monitoring, activity tracking and better charge hold capacity.

Fitbit Charge 4 Fitness Tracker

Does Fitbit Charge 4 provide accurate heart rate monitoring?


Fitbit’s Charge 4 comes with heart rate monitoring, SpO2 or oxygen saturation monitoring, GPS tracking and sleep time tracking. The general views on sleep tracking are very supportive of the device.

On a similar basis, the heart rate monitors and oxygen saturation monitoring have had some bit of questionable recording of data. Some users have complained of inaccurate heart rate monitoring. This feedback may be pretty genuine, but it needs to be understood that the heart rate monitoring, especially during activity tracking, may go off a bit. This would happen with any other fitness tracker. Most fitness trackers make use of optical heart rate sensors to provide heart rate monitoring on fitness trackers.

Read the excerpt from the website of Fitbit to understand how the heart rate monitoring takes place on a Charge 4 –

When your heart beats, your capillaries expand and contract based on blood volume changes. To determine your heart rate, the optical heart-rate sensor in your Fitbit device flashes its green LEDs many times per second and uses light-sensitive photodiodes to detect these volume changes in the capillaries above your wrist. Then your device calculates how many times your heart beats per minute (bpm). The optical heart-rate sensor detects a range of 30-220 bpm.*

We use green LEDS because they maximize the signal detected from the capillaries near the surface of the skin. The optical heart-rate sensor also uses infrared light to determine when the device is on your wrist to improve the accuracy of your heart-rate data.

Data from an optical heart rate sensor will never be as accurate as the data pulled in for heart rate monitoring by the medical professionals through the use of ECG machines or otherwise. Infact, the National Library of Medicine has a study that was published on 28.04.20. This study measured heart rate monitoring accuracy of fitness trackers that made use of optical rate sensor technology. The subjects of study were the Garmin and MI fitness trackers. The general conclusions of the study are that the heart rate monitoring of fitness trackers works fine in general cases. During periods of activity and exercises, the fitness trackers may produce questionable heart rate data. The conclusions of the study are pasted below for ready reference:

Conclusions: The study reveals that commonly used optical heart rate sensors, such as the ones used herein, generally produce accurate heart rate readings irrespective of the age of the user. However, users should avoid relying entirely on these readings to indicate exercise intensities, as these devices have a tendency to produce erroneous, extreme readings, which might misinterpret the real-time exercise intensity. Future studies should therefore emphasize the occurrence rate of such errors, as this will likely benefit the development of improved models of heart rate sensors.

The link to study this study is – https://pubmed.ncbi.nlm.nih.gov/32343255/

From a usability perspective, I will not give Fitness Charge 4 any negative points for the heart rate monitoring. I suggest the same for fitness freaks. Fitbit Charge 4 is a pretty decent fitness tracker with a robust set of heart rate monitoring accuracy.

The data offered by heart rate monitor on Fitness Charge 4 provides useful benchmarks of your cardiac health. You will do well to make a baseline of your heart rate over a period of time. And, any exceptions to the measure heart rate monitoring data should be considered as an alarm about your well-being. To put it another way, the heart rate monitoring on Fitness Charge 4 offers useful macro-level insights about your health. Use it to know the overall state of health.