Why do I have such huge bowel movements after exercising?

January 24, 2006 11:11 AM

Why do I have such huge bowel movements after exercising?

Started exercising recently, doing cardio (treadmill, stairmaster, little jogging) with weightlifting. Work out for about an hour, half cardio, half lifting, with the cardio being the last thing. When done I drink lots of water, but not during.

Roughly 20 minutes to half an hour after finishing, usually have to go to the bathroom. It's a very urgent feeling, with a quick onset, usually a huge and loose bowel movement (though often urination also), that leaves me feeling tired afterwards. Not it's not painful, just weird to me.

I'm overweight, mid thirties and diabetic. Is this common for most people? Any particular reason it occurs?

posted by anonpeon to health & fitness (13 comments total)

The colon, among other things, absorbs water from the stuff that's inside it. People who are chronically constipated often don't drink enough water, which results in feces that are more and more desiccated and therefore harder to eliminate. I'm not a doctor, but I'm guessing that the big rush of water (that you drink after your workout) hydrates the contents of your colon, which makes for a voluminous movement (triggering the urge) which is easier to pass.

Not sure about why it would make you feel tired afterwards.
posted by penchant at 11:33 AM on January 24, 2006

Can't help with the why, but it happens to me at times, aside from the looseness. Some googling suggests that lack of exercise slows down the movement of stools through the gut, so I'm guessing you're just having the opposite effect.
posted by youarenothere at 11:35 AM on January 24, 2006

Have you changed your diet as well?

A little off topic, but it's my recollection that your body needs water while you exercise as well as after.
posted by KAS at 11:51 AM on January 24, 2006

My guess is the exercise is stimulating peristalsis, which is a normal bodily function.
posted by squeak at 11:53 AM on January 24, 2006

Just to provide another datapoint, I experience this, too. I'm in pretty good shape, exercise regularly, and need to make sure I'm near facilities half an hour after I run. So either it's not too unusual or I'm unusual like you.
posted by COBRA! at 12:06 PM on January 24, 2006

i would go with the new activity is throwing off your body's normal blood flow patterns. this article discusses the effect somewhat. blood is diverted away from your stomach, to your legs (most often) and loose bowel movements often result.
i have had the problem on and off for several years and just kind of accept it.
although there is the theory (which seems to hold very true for me) that exercising too hard will cause the same result on a greater scale, either sooner or just more dramatically.
i would suggest not doing as intense cardio, perhaps ease into it a little more.
posted by annoyance at 12:06 PM on January 24, 2006

What you're describing is not at all unique to you -- it goes way, WAY back evolutionarily. Most mammals have similar responses, usually associated with fight-or-flight. Think of it this way: your body is about to, or has just undergone, heavy exertion, and too much energy is going into digestion. Better to sacrifice some potential food energy now so that you can get away and eat another day.

For example, cats will sometimes vomit or defecate when threatened by a dog, so they can run away as fast as possible. The dog also gets distracted by the mess/smell and loses a few seconds in the chase.
posted by Araucaria at 12:21 PM on January 24, 2006

Quote: "While exercising, take sugar in a five percent solution to avoid dumping syndrome. Avoid ...too much sugar."
Further googling of dumping syndrome (pdf) implies it is not exercise-related, except that you mention you have diabetes. Dumping is related to blood sugar.

When you exercise (and sweat), your body should be removing water from your colon, solidifying your bowel movements. Something else is happening here.

My take (IANAD) is that dumping is (one of) the body's ways of reducing blood sugar, by getting simple sugars out of the small intestine before they can be absorbed. Like COBRA!, for years I had to plan my jogging route around available facilities. In my case, I drank only water, so the above quote didn't apply. However, sticking to a low-glycemic diet fixed my problem dramatically, so I'm implicating blood sugar. Why exercise should trigger dumping is still a complete mystery to me.
posted by mediaddict at 12:33 PM on January 24, 2006

This is called "runner's trots." It's mentioned in this month's Men's Health magazine. There are lots of reasons it might be happening, but most likely it's simply a result of you shaking up your intestines and bowels vigorously for an extended period of time.

It's not uncommon to see long-time runners squatting in bushes alongside the first few miles of race-courses.

Just be thankful that your, er, "urges," don't happen DURING your exercise.
posted by kevinmeyers at 1:19 PM on January 24, 2006

This is also me, except I'm lucky to make it until after the workout. Many's the time I've gone running about 20 minutes in. Very frustrating.

I stay well-hydrated all day. I do avoid sugar because of slightly-elevated blood sugar, so I'm wondering if that has something to do with it. Hope there's another fix besides a sugar solution, because that's not happening.
posted by frykitty at 1:51 PM on January 24, 2006

frykitty, I agree - the rest of the quote didn't really advocate a sugar solution, just that if you're going to rehydrate with an exercise drink use one with a minimum of sugar.

I hadn't heard of "runner's trots" before, so I'm doing a lot of reading right now. I find little mention of blood sugar as a cause, in spite of my personal experience.
posted by mediaddict at 4:10 PM on January 24, 2006

most likely it's simply a result of you shaking up your intestines and bowels vigorously for an extended period of time.


Oh. Considering the result, is this jostling of the intestines and bowels a good idea?
posted by anonpeon at 6:32 PM on January 24, 2006

So perfectly normal. The more fit you get the less often it will occur. That said, you'll probably want to eat a bit less the day of or night before.
posted by raaka at 11:28 PM on January 24, 2006