I have read that the following breathing technique can help relieve some discomfort during a GERD attack: put one hand lightly on your upper chest. Breathe from your stomach area as though you are drawing air in directly from there. Make sure (with the hand on your chest) that your chest is not moving. It sounds kind of silly but This has helped me on occasion when I’ve had reflux attack during the night. At the opposite end of the exercise spectrum: I have tried yoga for my IBS. Didn’t get very far with that after some of the positions caused reflux. I think tai chi is better for me.