I've been thinking a lot about breathing.
It's kind of weird, considering how long I've been doing it, but there are certain muscles I can choose to use, a certain depth, regularity, and timing which all can play a big role in how and how well I run.
The hardest thing, I think, is focus and concentration. If I'm able practice for 30 seconds before I get distracted by something I'm usually pretty surprised. And I really don't know if actively expanding my abs is really helping my speed. But I do know I go from wheezing to heavy breathing when I do it. Of course, it could also be explained by a subsequent drop in my pace.
I'm supposed to be running 1600 intervals on Tuesday, I think. It would be a great place to try to figure it out, if I could compare two intervals breathing "normally" and two focused on ab breathing. If I could keep myself focused on ab breathing for more than half a minute. And if there aren't confounding factors. :P