I know that people who are chronically constipated rely on walking and/or running to help keep them regular. When I was up with gall bladder attacks, I found that pacing around made things a tiny bit more tolerable, so I would certainly recommend that people with cramping problems try walking to see if that makes them cramp less, or helps get the gas out. People with D who fear going out in public too far might try getting a treadmill for their home. Standing up, for me, tends to keep me from feeling the need to go to the bathroom as often as well, so another plus to taking a walk. Walking at a moderate pace is probably the answer for people who have reflux. Running actually doesn't burn many more calories than walking, so most health professionals encourage walking instead, as it's easier on the knees, and, I would think, easier on the reflux as well. But if you like to run, then run as much as you feel comfortable with. Right now, they are recommending 30 minutes of exercise (walking, namely) 5-7 days a week. So that's never a bad place to start out, but if it really helps, walk/run as much as necessary to keep the cramping or constipation at bay.