See Heart Health
The new Moto 360 can track your heart rate in the background, read it on demand and track it while you workout to show you how your workouts impact your heart.
Once you turn on background monitoring, the watch will take your heart rate at regular intervals and then you can look back at your history. The Google Fit app on your watch will let you take your heart rate on demand.
When you workout, the monitoring is continuous, so you can see your average heart rate and the overall heart rate pattern during your workout.