You can check your heart rate any time using the built-in Heart Rate app, or one of the many specialized third-party apps dedicated to heart monitoring, like HeartWatch, Heart Monitor and Heart Analyzer. I also use Apple’s Heart Rate complication for starting a session right from my watch face. Plus, the Heart Rate app is a permanent fixture in my Dock.

If you own a Series 4 watch that sports a new electrical heart rate sensor that can take an electrocardiogram on the go, you can even receive a heart rhythm classification: whether your heart is beating in a normal pattern, if there are signs of Atrial Fibrillation, a heart condition that could lead to major health complications, and more.

As a quick reminder, your Apple Watch uses an optical heart rate sensor built into the back crystal. It was designed to measure your heart rate continuously during the workout, plus for three minutes after the workout ends, and determine your workout recovery rate. It takes background readings throughout the day when you’re still, and periodically when walking.

The optical sensor supports a range of 30–210 BPM. You can control which third-party apps have access to your health data from the Health app under the Sources tab.