Whether you just picked up jogging or you’re an elite marathoner, there’s one thing that unites all runners: the sudden urge to crap your pants mid-stride. It’s no coincidence: runner’s diarrhea (AKA runner’s trots) is a legit scientific phenomenon that affects up to half of people who lace up.

One of the most infamous cases of runner’s trots came in 2008 during the Göteborg half-marathon. When Swedish runner Mikael Ekvall reached the halfway point of the race, his legs weren’t the only things that started to tremble—his bowels did too.

The swede unleashed an eruption of liquid poop mid-race. Powering through the embarrassment (and the stench), Mikael managed a respectable 21st place finish, crossing the line with liquified feces trickling down his legs.

“Did you ever consider stopping to clean off?” a reporter asked.

“No, I’d lose time,” he said. “If you quit once, it’s easy to do it again and again and again. It becomes a habit.”

The story became an instant viral sensation, with Ekvall earning the nickname “bajsmannen” (Swedish for “poop man”). Even to this day, the cringe-worthy image is still meme-worthy. But before you poop shame Mikael, you should know that nobody is safe from runner’s diarrhea—including you.

In this article we’ll explore why running triggers the urge to poop, and more importantly, how to go the distance without needing to discharge your lunch into your shorts.

What Is Runner’s Diarrhea (AKA Runner’s Trots)?

Runner’s diarrhea is exactly what it sounds like: cramping followed by loose stool that strikes during or after a run. It can affect anybody at anytime, but it tends to happen mostly on distance runs.

You won’t find the term “runner’s trots” in any medical textbooks, but there’s no mistaking it: mid-run tummy trouble including nausea, bloating, and sudden onset diarrhea. Runner’s trots are especially troublesome for long-distance runners.

In a survey of 272 ultra-marathon runners who (people who somehow run 100-miles at a time), researchers found that 96% of finishers suffered from gastrointestinal symptoms like cramping, farts, sudden bowel movements, diarrhea, and even bloody stool (yikes.) What’s worse, some of those runners even had to drop out of the race because their intestines got the best of them.

And if you thought it was just pros and hardcore racers that get the urge to “go” on the run, think again. In a study of 279 leisure runners, half of them disclosed that they had “altered bowel habits:” loose poop and more frequent bowel movements.

So, if you’re a runner who has been ashamed of a poopy past, take solace in the fact that you’re not alone.

3 Potential Causes of Runner’s Diarrhea

Runner’s diarrhea is likely caused by a combination of factors including repetitive motion, diet, and decreased blood flow to the digestive tract. However, doctors haven’t nailed down an exact cause—it can also vary from person to person.

Let’s take a closer look at the leading theories.

1. Your Pre-Run Meal

As with any poop-related issue, the first subject in questioning should be your dietary choices. Here are some common culprits of running-related diarrhea:

• High fiber foods: The fiber in fruits, veggies, beans, and whole grains creates the perfect storm for loose bowel movements. Mayo Clinic recommends avoiding these trigger foods before you run, especially on race day.

• Coffee: Caffeine might seem like a good idea before a run, but that cup of joe will be rocket fuel for the hershey squirts once you start pounding the pavement. (That goes for the caffeine in energy supplements too).

• Artificial sweeteners: Tons of sports drinks are loaded with sugar alcohols, sorbitol, and other sweeteners which are notorious for causing diarrhea.

• Dairy products: Lactose is a big no-no before running, especially if you’re lactose intolerant.

The one thing you do need in your system before a run is water. Hydration is essential for any exercise, but it also regulates your digestive system.

2. The Motion of Running

You know how a can of soda explodes after you shake it up? Same thing goes for your gut. That constant jostling of your intestines gives you the urge to go.

3. Blood Flow Problems

Running is intense exercise, especially for extended periods of time. When your body pumps blood to your legs and heart to keep you moving, it’s diverted away from your intestines, causing plumbing problems in the GI tract.

It’s worth noting that the odds of getting runner’s diarrhea could increase if you have pre-existing gastrointestinal problems like irritable bowel syndrome (IBS), or inflammatory bowel diseases (IBD) like ulcerative colitis. When your stomach is sensitive to begin with, running can add fuel to the fire.

How to Prevent Runner’s Diarrhea

We want you to cross the finish line with clean undies, and so does everyone watching. We haven’t found a cure for runner’s trots, but these quick tips might spare you from a stink attack.

1. Start short and slow. Easy there, Speed Racer. Increase your distance and intensity gradually so you don’t send you body into poop shock when you pound the pavement.
2. Take a pre-run poop. If you clean the pipes ahead of time, there won’t be much left to leak.
3. Snack Smart. Fiber is like rocket fuel for your poop. Enjoy your fruits and veggies with caution.
4. Stay hydrated. Your gut needs water to keep the inner plumbing in check. As a rule of thumb, try to get your pee as clear as possible.

If all else fails, you’ll have to pop a squat out of public sight or make a detour to a porta potty (just make sure you have some clean-up material handy.) Chances are you’re not going for a world record, so take your time.

Otherwise, you’ll have to pull a Mikael Ekvall and let it rip mid-stride.