I would like to know what causes the urge for a bowel movement during a run. I am not constipated, and often times will go to the bathroom a couple times just before going out to run. But within the first couple miles, I have to walk, and sometimes completely stop moving, because of the urge to go again. It doesn't seem to matter whether I run in the morning or evening. What is causing this sensation and how can I overcome it?
Ron, this happens for some people. The viscera have blood pulled from them as your musculoskeletal system demands more oxygen during the first part of your run. What you are experiencing is not dissimilar to the sensations a person feels when vigorous exercise causes them to puke following intense exercise. The best advice I can give you is to try to get on a regular bowel program so that you void your bowels in a very consistent fashion on a daily basis. You can effectively regulate your bowel movements by your diet and caffeine intake schedule, and time your runs to follow a regular voiding of your bowels and bladder.