Ever Wonder Why Running Makes You Have to Poop?

You're not the only one.

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Going on a run is all fun and games until you have to poop. The phenomenon isn't something friends usually talk about over brunch, but it's nothing new to the running world.

Runner's diarrhea, aka frequent loose bowel movements during or immediately after a run, happens to everyone from casual joggers to marathon runners. But what causes all that discomfort? Anna Rothschild of Gross Science broke things down in her latest video.

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It turns out having to hit the bathroom mid- or post-run is pretty common, so don't feel ashamed the next time you get the urge on a jog. There's no definitive answer as to why this happens, but here's what scientists think is going down in our bowels.

1. Your Internal Body Temperature Rises

You might be sweating on the outside, but your insides are getting steamy, too.

"When you heat things up, they tend to get kind of... melty. That's probably part of what happens to the feces in your colon," Rothschild says.

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2. The Bounce of Your Feet Landing Causes an Emulsifying Effect

Basically, that's a nicer way of saying running shakes things up in your digestive system. The bouncing puts more pressure on your colon, giving you that must-go-now feeling.

3. Your Stress Level and Hormones Get Out of Whack

Stressed out before a race? Rothschild says your nerves alone can make you head straight to the bathroom. Hormone fluctuations during exercise can do the same thing.

4. You're Dehydrated and Have Limited Blood Flow

Big-time runners might end up with bloody stools thanks to being dehydrated and having limited blood flow to their bowels, which Rothschild says causes damage to the intestinal lining.

How to Help Prevent Running Poos

Rothschild recommends staying hydrated and going to the bathroom before your run. But if runner's diarrhea is becoming a serious issue for you, talk to your doctor, who might be able to give you a medication to slow your digestive system down a little.

Barring all else, be prepared: Choose a running path that has lots of bathrooms along the route.

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