Pelvic tilt and running...

[CheryG]

So, I'd been having some trouble with breathing, and it felt like it was coming from the lower abdomen and not my lungs, if that makes sense.  Then, when running some intervals I felt a change that all of a sudden let me inhale so mch better from my abdomen.  My experiences in riding made me focus on what my pelvic tilt was when the breathing- got better- it seemed to simply let my abs be free.

I googled, and this appears to be a thing.

Any advice as to how to know what is right?  Riding requires me to have it more posteriorly tilted, or the horse falls on its face.