Because nothing ruins a good run like the frantic hunt for a restroom.

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If you're a runner, you've probably been there: You're enjoying your run, and just as you should be upping your intensity or hitting a new PR, your GI tract starts rumbling and contracting. If you don't hightail it to a restroom quickly, your bowels are going to start moving, too. Turns out, there's a name for this phenomenon: runner's trots. 

Runner's trots include a wide range of symptoms—nausea, cramping, gas, flatulence, "and ultimately, the urgent need to defecate," Rosario Ligresti, MD, chief and director of gastroenterology at the Pancreas Center at Hackensack University Medical Center in New Jersey, tells Health. Runner's trots are also known as runner's diarrhea, but the term encompasses any type of sudden mid-run bowel movement, notes Dr. Ligresti. 

While annoying and potentially embarrassing, runner's trots are usually nothing to worry about. "They're a physiological phenomenon, not a disease," Waqas Nawaz, MBBS, a gastroenterologist at the Ohio State Wexner Medical Center, tells Health

Still, completing a run without having to stop for an urgent bathroom break is ideal. To reclaim your run, learn why runner's trots happen—and how to make them stop.

What's happening in your body when you get runner's trots?

As you start running, a slew of different changes happen in your system. When your feet hit the pavement, vibrations roll through your body and jostle your intestines up and down. "This likely contributes to a more rapid passage of fecal contents through them, resulting in that OMG feeling that you've gotta go," says Dr. Ligresti.

As you increase your intensity, your GI functioning might start to shift, thanks to changes in hormone levels and they way your gut and brain communicate, says Dr. Nawaz. And on the cusp of peak oxygen demand, your body redirects a whopping 80% of blood flow from your gut to higher-need areas like your muscles, heart, lungs, and brain. 

This diversion deprives the cells lining your intestines of oxygen and fuel. In turn, that can contribute to microscopic damage and irritation, plus symptoms including GI pain, cramping, gas, diarrhea, and sometimes even rectal bleeding, according to Mayo Clinic

What should you do when you get runner's trots?

In the moment, the best (and most obvious) remedy for runner's trots is to head for the nearest restroom. Slowing to a walk might help dial down that gotta-go-now sensation, so try that—even though the urge is likely to come right back when you pick up your pace again. 

One thing you shouldn't do is take anti-diarrhea medications like bismuth subsalicylate (Pepto Bismol) or loperamide (Diamode). These meds could actually cause more damage, since they decrease the flow of fluids to your already-deprived intestines, says Dr. Nawaz, and reduced blood flow can worsen symptoms.

How to prevent runner's trots

Since you can't do much to stop the trots, the key is to prevent them from striking in the first place. A few simple changes to your pre-workout routine can help that happen:

Avoid trigger foods

Two to three hours before going for a run, limit or cut out foods known to cause gas or loose stools, per Mayo Clinic. These include dairy products, high-fiber foods, high-fat foods, and sugar replacements like sorbitol or isomalt. In fact, it's a good idea to not eat anything two hours prior to lacing up your running shoes, suggests Dr. Ligresti, so you're running on an emptier stomach.

Hydrate well

You'd think too much water would lead to diarrhea, but the opposite is true: Dehydration is known to cause the runs because lower blood plasma volume can in turn decrease blood flow to the intestines. Dr. Ligresti's advice: "Stay hydrated by drinking at least 16 ounces of water approximately 90 minutes before your run and 8 ounces of water every 20 minutes during the run."

Carefully time coffee

Although caffeine is commonly found in pre-workout supplements, it's also a laxative. Limit your intake of coffee, tea, or any other caffeinated drinks to three to six hours before you hit the pavement.

Save pain relievers for post-run recovery

Don't take over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Advin, Motrin) or naproxen (Aleve) for at least 24 hours pre-run, says Dr. Nawaz, since they could upset your stomach.

Stick with your usual diet

"Most importantly, don't try out new foods before a run," says Dr. Ligresti. You never know what might turn your stomach, especially if you're traveling and eating foods you're not familiar with. If you're hungry before a run, fuel up with low-fiber, easy-to-digest carbs like a bagel, English muffin, pasta, or rice, he suggests. 

When should you see a doctor about runner's trots?

If your trots involve explosive diarrhea, last longer than 24 hours, are a regular occurrence every time you run, or comes with other concerning symptoms (like blood in your stool, nausea, or ongoing abdominal pain), schedule an appointment with a health care provider. 

Digestive distress can have many causes, both physical and mental, so don't panic if your runner's trots seem like something more. At the same time, "these red flags may be a sign of something more serious and require further examination," says Dr. Ligresti. "Do not take them lightly." 

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