# Why does cardio execise often cause bowel movements? (TMI) **URL:** \ **Category:** Factual Questions\ **Created:** [June 24, 2010, 2:01pm UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352 "2010-06-24T14:01:14Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![dalej42](https://avatars.discourse-cdn.com/v4/letter/d/67e7ee/32.png) [@dalej42](https://boards.straightdope.com/u/dalej42)\ **Post date:** [June 24, 2010, 2:01pm UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/1 "2010-06-24T14:01:14Z")
Is there any reason I’ll often have a bowel movement after about 30 minutes of a cardio workout? There isn’t a restroom in the gym at my apartment complex and I have to painfully walk back to my apartment. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [June 24, 2010, 2:17pm UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/2 "2010-06-24T14:17:49Z")
Are you drinking a lot of water. That can help flush things out. Note, you are not alone. There are many runners who experience the same thing, and it has to do with the exercise stimulating the bowels to contract. In some people, the bowels are stimulated by exercise, or by up/down pounding (such as running). All I need to do is some heavy ab work. Some people find it happens when running, and others after aerobics. For runners, many can’t deal with the problem because it happens 1/4 of the way through a run, and then what? no place to go! Good luck. You are crossing into an area where medical advice is gonna start creeping in, so google around. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [June 24, 2010, 2:21pm UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/3 "2010-06-24T14:21:16Z")
After you run blood flow is being diverted from the gut to the muscles. The relative lack of blood supply can trigger diarrhea. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [June 24, 2010, 2:22pm UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/4 "2010-06-24T14:22:16Z")
[Requisite linkee.](http://www.jeffgalloway.com/training/injury_archives/trots.html) ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [June 24, 2010, 9:14pm UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/5 "2010-06-24T21:14:24Z")
> [@DSeid](#): > > After you run blood flow is being diverted from the gut to the muscles. The relative lack of blood supply can trigger diarrhea. Actually your link states that this happens during the run, not afterwards. The OP did not mention diarrhea, just the need for a bm after working out. This is a common occurrence. My take on it is that exercise increases peristalsis. ---
**Author:** ![SeaDragonTattoo](https://avatars.discourse-cdn.com/v4/letter/s/df705f/32.png) [@SeaDragonTattoo](https://boards.straightdope.com/u/SeaDragonTattoo)\ **Post date:** [June 25, 2010, 1:35am UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/6 "2010-06-25T01:35:41Z")
There’s a reason for the old saying about taking a walk after dinner to aid digestion. “Digestion” used to be code in more genteel times for moving bowels. What I’m really curious about is, why painful? Pooping or needing to poop shouldn’t be painful. ---
**Author:** ![Savannah](https://avatars.discourse-cdn.com/v4/letter/s/b3f665/32.png) [@Savannah](https://boards.straightdope.com/u/Savannah)\ **Post date:** [June 25, 2010, 1:36am UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/7 "2010-06-25T01:36:48Z")
…and that’s why we walk the dog to assure a supervised bowel movement? ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [June 25, 2010, 3:38am UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/8 "2010-06-25T03:38:35Z")
> [@SeaDragonTattoo](#): > > There’s a reason for the old saying about taking a walk after dinner to aid digestion. “Digestion” used to be code in more genteel times for moving bowels. > > What I’m really curious about is, why painful? Pooping or needing to poop shouldn’t be painful. Trying to hold it in when you REALLY need to go can be _very_ uncomfortable. I find I only get this from running, other cardio exercises like rowing or cycling don’t have the same effect. After one very near miss and another time that went one step further–luckily late at night with no one around to notice–I’ve become very careful about when I run in relation to meal times and bowel movements. Best time is with no food in the stomach and having just done a BM. ---
**Author:** ![Freudian\_Slit](https://avatars.discourse-cdn.com/v4/letter/f/5daacb/32.png) [@Freudian\_Slit](https://boards.straightdope.com/u/Freudian_Slit)\ **Post date:** [June 25, 2010, 3:41am UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/9 "2010-06-25T03:41:30Z")
It sometimes happens to me. Like if I run then a little later, I’ll need to go. Or if I kind of need to go after I’m done running, I’ll definitely need to go. Once in a while it’ll also give me period type cramps (even if I’m not on my period) and that’ll sort of feel linked to that needing to crap feeling. I think we had a thread on that once a while back actually but I’m forgetting what we concluded. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [June 25, 2010, 5:21am UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/10 "2010-06-25T05:21:49Z")
> [@barbitu8](#): > > Actually your link states that this happens during the run, not afterwards. The OP did not mention diarrhea, just the need for a bm after working out. This is a common occurrence. My take on it is that exercise increases peristalsis. First off the op not asking about something that occurs 30 minutes after working out, but about something that occurs after working out for 30 minutes. IOW something that interrupts the activity, not something that occurs at rest later. Significantly decreased gut blood flow occurs during and after exercise. It can be severe enough to cause significant ischemia. OTOH, exercise does _not_ increase peristalsis - if anything it slows it down. See [here](http://www.ncbi.nlm.nih.gov/pubmed/2604760) and [here](http://www.ncbi.nlm.nih.gov/pubmed/9062051) and [here](http://www.ncbi.nlm.nih.gov/pubmed/15692319) and [here](http://www.ncbi.nlm.nih.gov/pubmed/14634826) and well you get the point. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [June 25, 2010, 6:38am UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/11 "2010-06-25T06:38:50Z")
Oh, [cite](http://gut.bmj.com/content/28/5/583.abstract) for reduced gut (splanchnic) blood flow both during and after excercise. ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [June 25, 2010, 10:39am UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/12 "2010-06-25T10:39:37Z")
> [@DSeid](#): > > Oh, [cite](http://gut.bmj.com/content/28/5/583.abstract) for reduced gut (splanchnic) blood flow both during and after excercise. That link states: > [@](#): > > After treadmill exercise (speed 5 km/h, gradient 20%, duration 15 min) in 16 subjects, superior mesenteric artery blood flow decreased by 43% immediately after the end of the exercise and by 29% at five minutes and 24% at 10 minutes postexercise. No measurement was done, apparently, after 10 minutes. Considering the drop from 43% to 24% in 10 minutes, it would be reasonable to assume that by 30 minutes after the end of exercise, blood flow would have returned to normal. It could be (but I have no cite) that the blood flow, having been returned to normal, would cause a BM. Anecdotally, I know from my own experience that certain exercises (but not running) causes a BM. I’m referring here to calisthentic-type exercises, especially those involving the body core. ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [June 25, 2010, 11:03am UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/13 "2010-06-25T11:03:30Z")
The OP did say after about 30 minutes of exercise and not about 30 minutes after exercise, but he did not state how long after. However, considering how quickly the blood flow returns to normal (apparently, but no studies done after 10 minutes), the return of blood flow could cause a BM, if the need is sometime after 10 minutes. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [June 25, 2010, 5:21pm UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/14 "2010-06-25T17:21:17Z")
> [@DSeid](#): > > Oh, [cite](http://gut.bmj.com/content/28/5/583.abstract) for reduced gut (splanchnic) blood flow both during and after excercise. You mean ‘splanchnic’ is a real word? I thought they just made it up for that episode of _Futurama_. ---
**Author:** ![mo50](https://avatars.discourse-cdn.com/v4/letter/m/8797f3/32.png) [@mo50](https://boards.straightdope.com/u/mo50)\ **Post date:** [June 27, 2010, 1:19am UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/15 "2010-06-27T01:19:37Z")
Don’t know the technicalities, I guess I always thought it was just the effect of shaking things up for 20-30 minutes, but yeah, the post cardio duece is pretty common, for me at least. (Sorry if that was an overshare!:smack:) ---
**Author:** ![dalej42](https://avatars.discourse-cdn.com/v4/letter/d/67e7ee/32.png) [@dalej42](https://boards.straightdope.com/u/dalej42)\ **Post date:** [June 27, 2010, 1:40am UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/16 "2010-06-27T01:40:13Z")
To clarify, I usually have to have the bowel movement after the 30 minute mark in a 60 minute workout. It is very annoying. ---
**Author:** ![Honesty](https://avatars.discourse-cdn.com/v4/letter/h/f04885/32.png) [@Honesty](https://boards.straightdope.com/u/Honesty)\ **Post date:** [June 27, 2010, 6:50am UTC](https://boards.straightdope.com/t/why-does-cardio-execise-often-cause-bowel-movements-tmi/544352/17 "2010-06-27T06:50:54Z")
> [@dalej42](#): > > Is there any reason I’ll often have a bowel movement after about 30 minutes of a cardio workout? There isn’t a restroom in the gym at my apartment complex and I have to painfully walk back to my apartment. Here’s a pertinent article [here](http://ajpgi.physiology.org/cgi/content/full/276/5/G1221). The authors suggest that exercise actually decreases propulsion of the feces during exercise but increases substantially post-exercise. Coincidentally, the results concur with your own observation of consistent post-exercise bowel movements. - Honesty