Improve recorder app for runners

Actual distance travelled?

Ah yes, of course !

Heart rate zones (graph showing how long HR was in each of 3 zones)

3 zones ? Not 5 ? I do agree that zone 1 is not used at all for sport. Also, I can't but some people do run in zone 2, people cycling may also use this zone (?). Globally I think these 2 first zones will be empty for most of he users, but if the first zone displayed is the zone 3, it might be confusing.

saving the stats that are displayed in the Run app. They could also just be calculated from recorded data though...

The more precise the better I suppose. I'm ready to wait 15 seconds (for the calculations and processing) at the end of my run to get more precise informations displayed and saved. But if you need to call data from another app inside "run app" it may defeat the simple design approach ?