Few people know, but the Apple Watch has two optical heart rate sensors on the back of the device: two green LED lights and two infrared sensors. While the first uses photoplethysmography technology, responsible for the strong green light emanating from the LEDs, the second runs imperceptibly in the background, monitoring your heartbeat every 10 minutes.
An interesting curiosity is that the green LED lights blink thousands of times, but at a speed that human eyes cannot detect, suggesting that they are simply lit. If your bracelet is looser than usual or the position of your watch is not ideal, the shade of green will become stronger and more intense.
Also, because infrared sensors aren’t as accurate as photoplethysmography technology, the Apple Watch automatically detects when your heart rate isn’t being accurately monitored and switches to the green sensor.
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Learn how to use the Apple Watch heart monitor in the steps below:
- Open the “Heart” app on your Apple Watch. You can do this through the app list or through a complication on one of its displays;
- You will be able to view on the main screen a monitor of your heart rate recorded throughout the day and the current appointment;
- Click on “Current” at the top left of the screen and you will also be able to view your average heart rate recorded at rest times or during walks throughout your day;
- Enter the Watch app on your iPhone, then “Heart”. Confirm that the “Irregular Pace” option is activated. This feature can identify when your recorded heartbeat is irregular in relation to your usual rhythm;
- Under “High Beats”, set a number of heart beats that you consider too high for your daily life. Don’t worry, the Apple Watch can automatically identify when you’re on the move, whether you’re walking, training or exercising, and it will disregard the alert for these moments;
- Go back to the previous screen and enter “Low Beats” to set a number of heart beats that you consider too low not only for your daily life, but also during rest, if you usually sleep with the watch on your wrist.