When you start the activity it should notify you of the HRM Pro sensor being detected. That heart rate is used in the Connect app for the activity. This provided you connected the HRM Pro as external sensor to the watch of course. There should not be double counting as the watch would use the HRM to measure heartrate. COOSPO Bluetooth Heart Rate Monitor Chest Strap H808S, ANT+ BLE HR Monitor Chest, HRM IP67 Waterproof, Use for Running Cycling Gym and Other Sports dummy Garmin 010-12955-00 HRM-PRO, Premium Heart Rate Strap, Real-Time Heart Rate Data and Running Dynamics So the purpose of the pod is to replace the data given by your HRM-TRI or HRM-RUN straps. Or rather more specifically, the Running Dynamics data from those devices. The idea behind it is with the rise of optical HR sensors, it seemed silly to keep requiring people to buy HR straps – creating duplication. You can use your hrm pro as a tracking device for heartrate, intensity minutes and calories by adding it in the garmin connect app as a device. But this wont show you a seperate workout, just the daily stats. If you want a workout you can look into, you have to press start on your watch, do your workout even without a permanent connection and .

how to connect garmin hrm pro