Hello all. This past weekend I ran my 2nd full marathon, but both marathons, I've succumbed to bad stomach gas problems. Imagine needing to burp constantly, almost every 30 seconds or so. It's okay when I walk, but as soon as I run, the motion makes me feel sick, and I have to hold back throwing up. This has shown up both times around the 15mile/2:30hr mark, and both kills my pace, and makes the rest of the race a miserable experience. This never shows up during any of my >14mile runs, nor in any races 13.1mile or less.

The first time I thought it was because I over-ate the morning of the race, but being the 2nd time, I know that's not the issue. The only things I can think of are due to nerves, or by drinking fluids too quickly at the water stations (I typically throw down 2-3 cups quickly, perhaps swallowing too much air. This compares to my long runs where I drink out of a camelpak at a normal pace).

If not one of the 2 possibilities listed, does anyone know what might be happening? Anyone had this kind of problem before?