Are third party running apps (Nike+ for example) able to update the exercise and calorie ring? Is a built-in workout the only thing that can update those rings?
There is no api or sdk to interact with the rings as far as I have researched. (if anyone knows different, I would love to know!)
However, anytime your moving at a brisk walk, or even aggressively cleaning the house, they update.
But if for example you leave your watch at home, and go for a jog that records a run, like run keeper, it won't update the activity ring, as your watch _itself_ didn't detect that you were being active.
This is something I hope changes in future releases of WatchOS/Activity App.
Cheers
The Workout app doesn't update the exercise ring - they work independently. The exercise ring simply fills up by monitoring your HR and adding time when it goes above a certain level. Doesn't therefore matter whether you use the native Workout app or a third party running app for these purposes.
I would agree with the post that if an app writes workout data, it will update exercise ring.