I agree with you W, that it plays a major role in our existence......and we treat it so badly! I liken it to putting sugar into our cars' gas tanks, then wondering why the car won't run! I don't think our GI tracts are made for today's kind of living.
I seem to go through flare-ups with my GERD. Fortunately, it's been under control for quite awhile, but antibiotics definitely flare it up, plus something else seems to flare it up cyclically. Perhaps my female hormones? I went through a couple of years where I had a ton of irregular heartbeats, and I swear it was from my GERD. I'm sure we have tons of nerves in our esophoguses, and I think when they are irritated, funky things can happen.
Perhaps your acid does just slosh up when you run David. I know my eyes jiggle so badly when I used to run, that I couldn't see! One thing that gives me reflux almost 100% of the time, is just drinking plain water. I think it mixes so easily with the acid, and then can come backwards through the LES really easily. Do you drink alot before and during your run? Ordinarily, it's really good to drink alot, but maybe that worsens things for you.
It's a bummer to really enjoy something, and have it be so good for you.......but it causes you this other problem.