09-29-2018 09:14
09-29-2018 09:14
09-30-2018 00:39
09-30-2018 00:39
If you record your workout (manually) by swiping right on the home screen and selecting the exercise app (and then swipe to whichever workout you are doing), before you tap to start you can select the little gear in the top left corner to customise what's on your screen during your workout.
If you are relying on smart track or auto exercise recognition, the only way to keep you HR on the screen would be to change your clock face to one that displays HR data.
Pages 42-45 of the user manual might be of some use to you.