So I've always wondered what about running makes you have to go to the bathroom? Why is it that it seems to accelerate the downward progress of any ... you know ... Or maybe I'm the only one this happens to?

I'm asking seriously, I want to know why!

  • 31
    This is a really crappy question... :-p
    – JasCav
    Commented Mar 7, 2011 at 21:48
  • 1
    A good reason to do treadmill running!
    – Chris S
    Commented Nov 14, 2011 at 19:33
  • As someone who is working up to running more consistently, I sure am glad I stumbled onto this question.
    – Paperjam
    Commented Feb 27, 2012 at 10:31
  • I have the same problem. I think personally it's healthy though, because I am lactose intolerant (hard core) and I have a very hard time going to the bathroom sometimes, ever since I have been running (and eating right for me) I have been way more regular, maybe too regular, and I feel great!
    – user3373
    Commented Apr 23, 2012 at 11:46
  • Even elite runners like Paula Radcliffe deal with this!! youtube.com/watch?v=W6I2-YP42rs
    – Jason
    Commented Aug 9, 2015 at 18:58

3 Answers 3


You're not the only one this happens to, exercise is one of the best natural laxatives.

What I found interesting is that any physical activity can help prevent constipation, because it isn't just the physical rebounding of the gut from running which loosens things up, the colon also gets stimulated so it can both absorb the nutrients you'll need while exercising and expel waste more efficiently. So, any exercise will actually have a laxative effect.

From the Mayo Clinic:

Physical activity increases muscle activity in your intestines. Try to fit in exercise most days of the week.

  • 2
    In my experience, running has a uniquely strong effect that goes way beyond the laxative effect of exercise generally Commented Mar 27, 2011 at 15:10
  • 1
    Heavy squats. If you haven't been to the bathroom beforehand, well, after a set or two, the rest time gets a bit longer... Commented Apr 23, 2012 at 13:36

It may be a combination of running and your diet. Generally, you should stay away from a high fiber and high fat diet 24 hours before a long run. I also recommend holding back on as much fiber and fat as you can until you complete a regular run for the day.

  • A very high protein content could also cause problems as protein is very slow to digest but much of this can vary by individual. For various friends and running groups that I've led before I usually tell people to experiment a bit during training so they know what does/does not work well for them come race day.
    – nurdyguy
    Commented Jul 30, 2018 at 19:40

"Runner's trots" or an increase in the need to hit the port-a-john during or after a run is most often attributed to a general decrease in blood flow to the intestines, altered hormones and absorption levels, and “jostling” of the gut (think about what happens to a ketchup bottle when you turn it upside down and smack it).

Here's a link to an short article that goes a bit more in depth.

  • "Runner's trots" is actually (usually) due to overhydration. Runners tend to over-prepare for a big race and can often drink too much water. This then results in the aforementioned. I read an article in Runner's World about it a while back but can't seem to find it.
    – nurdyguy
    Commented Jul 30, 2018 at 19:36

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