heart rate monitor
Monitor your heart rate with the help of the Apple Watch's built-in Heart Rate app. Open the app, and it will measure your current heart rate. As long as your watch is in display mode, or you glance at the face, measurements are periodically taken to record your rate. Tap the arrow in the upper left, and the app displays your current rate, your resting rate, your average rate, and specific rates based on your activities.
Don't like the Heart Rate app? There are several alternatives that can monitor your heart rate and possess more bells and whistles than the built-in option. Apps like Cardiogram, Heart Analyzer, HeartWatch, and Talking Heart Rate are worth considering.