watchOS already had the ability to turn on high heart rate alert. And with watchOS 5, Apple has made it possible to enable low heart rate alert also on Apple Watch.
So how does this new add-on work? To get started, you must enter the batch per minute (BPM) threshold. After that, Apple Watch will inform you when it finds your heart rate below the specified BPM level while you have been idle for a period of 10 minutes. It's as simple as that!
To enable low heart rate alerts on Apple Watch
Note: Make sure you have Apple Watch Series 1 or later that starts with watchOS 5.
Step # 2. ] Click on