Apple watch syncing steps with other apps
My Apple watch is tracking fine in the health and activities app and syncing with my iPhone. I have an app I love to run to called Zombies, Run! There are settings where you can have it track your distance by GPS or by steps/step length. I love the idea of not having to carry my phone with me now for the app to track it when I'm running on the treadmill. I can't get step tracking to default to the Apple watch so the app knows my steps. It only works with the iPhone. Is there a way to default steps to the Apple watch, and if so, is it just the app that is incompatible with recognizing steps through the apple watch?
Apple Watch Series 2, iOS 10.2.1