Thanks for the suggestions. I will look into the yoga breathing exercises. They sound similar to the Iqoro exercises I already do but still worth researching and trying.

I use ENTs Aviv and Koufman for advice and the low acid, low fat whole food diet has worked fairly well, as long as I stick to it. Koufman has a decent web site with a lot of information, they both have books on GERD and diet/lifestyle approaches. There is a FB group that has a lot of low acid recipes based on Aviv's work.

The Doctor Yourself link you offered had a suggestion of eating fresh pineapple for its digestive qualities. That's a no go for those of us on a low acid diet if anyone else looks into that. The eating almonds to calm a reflux attack was something I haven't tried before. Maybe almonds before abdominal exercises will keep the chest pain at bay. I will find out!

BTW, another non-drug option to keep chest pains away during exercising is chewing sugarless gum. That has worked for me in all aspects except the abdominal exercises.