All models Apple Watch have an optical heart rate sensor, but the Series 4 also has an electrical sensor for an electrocardiogram in the ECG app. Did you know you can use this sensor to measure your heart rate faster?
Anyone can measure heart rate faster and more accurately on the Apple Watch Series 4, regardless of where you live or how old you are. The feature works in watchOS 5.1.2.
How to measure your heart rate faster
1) Open the Pulse app on Apple Watch Series 4.
2) Place your finger on the Digital Crown.
The app measures your heart rate faster and more accurately. You will see measurements every second instead of five seconds as before. The same measurements are available on older smartwatches using external heart rate monitors.
Also read: How to use the ECG app on Apple Watch
This feature is only available on Apple Watch Series 4 with watchOS 5.1.2+ as it works with a new electrical heart rate sensor. Unlike the ECG function, this one is not only available to US residents.
The Series 4 has electrons built into the Digital Crown and watch back. When you place your finger on the Digital Crown, it creates a closed circuit and the watch can measure the electrical impulses of your heart.