Ok so the apple watch does not graph your heart rate during exercise it only shows the average HR but it does send the data to health kit. Unfortunately it is not in a very useable format. When I had my fitbit i Was able to see my HR over the course of exercise and see where I was within Cardio and Fat Burn zones. Does anyone know of an app on the iPhone that will take the HR data from Healthkit and display it in graphical format as I am suggesting?