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There’s a lot I love about running: the stress-banishing endorphin boost, the unmatched cardio challenge, the fact that you can essentially do it anywhere.
But one aspect of the sport that doesn’t make the list? Runner’s diarrhea. Yes, this phenomenon is pretty much exactly what it sounds like (precise medical definition in a minute), and yes, it’s as disruptive-slash-unpleasant as you might imagine.
If you’re a runner like me, chances are you’re already familiar—perhaps too familiar—with this unfortunate occurrence, also known informally in the running community as “runner’s trots.”
“Let’s just say that anyone who considers themselves a runner will likely admit to having runner’s diarrhea at some point in time,” runner and gastroenterologist Amy S. Oxentenko, M.D., a fellow of the American College of Physicians, American College of Gastroenterology, and American Gastroenterological Association, and professor of medicine at the Mayo Clinic, tells SELF via email.
“I probably discuss the topic with nine out of 10 of my running [clients],” Lydia Nader, Chicago-based registered dietitian and marathoner, tells SELF.
Caolan MacMahon, a Boulder, Colorado-based long distance runner and certified running coach, tells SELF about 25 percent of her clients have experienced it chronically or cyclically.
So yeah, the trots are annoying and surprisingly not all that rare for runners. What’s even more frustrating, though, is that they can strike seemingly out of nowhere and during the least ideal moments, like in the middle of a race or when you’re soul-crushingly far from a bathroom. The good news is that, as inevitable as they may seem, there are certain steps you can take to reduce the likelihood of a mortifying mid-run poo.
Here, six experts get real on runner’s diarrhea, explaining the potential causes, what you can do to minimize your risk, how to best manage the urge when it hits, and when the issue might warrant a convo with your doc.
Here’s why running can lead to pooping.
Before we dive into everything, let’s get clear on what, exactly, constitutes runner’s diarrhea. Dr. Oxentenko describes it as “a change in stool form (looser or watery) or frequency (number of stools) that occurs in a runner, and may occur immediately before, during, or after running.”
The cause of this crappy phenomenon (sorry, had to) is varied and changes from runner to runner. In general, though, it “can be somewhat broken down by timing of when it occurs during the run,” says Dr. Oxentenko. If you have a pre-race case of the runs, for example, it’s “often due to the adrenaline surge and excitement of a race,” (yup, your brain can definitely impact your bowels) and could be intensified by what you eat or drink earlier in the day, she says.
Run-related crapping during or post-run could be caused by a number of things, but the most common factor is what you eat—either before or during a run, says Dr. Oxentenko.
On the food front, high-fat items are one of the biggest culprits, says Nader. That’s because it takes your body a long time to digest fats—longer than it does protein and carbs. So if you have a high-fat dinner, for example, and then go on a run the next morning, the food could still be lingering in your intestinal tract. Then, when you start running, that not-fully-digested food could cause GI distress and ultimately, diarrhea, Katherine Zeratsky, a registered dietitian nutritionist at the Mayo Clinic and Rochester, Minnesota-based runner, tells SELF.
Another possible dietary cause is high-fiber foods, like bran and legumes, as well as certain fruits and vegetables, says Dr. Oxentenko. These can cause gas and bloating, she says, “and may rev up gut transit, leading to strong urges during running.” Another possible culprit is snacks or beverages—like energy or snack bars and certain sports drinks—that contain sugar alcohols in place of sugar. Sugar alcohols, particularly when consumed excessively, can cause an unpleasantness known as osmotic diarrhea.
This is due to the way sugar alcohols move through your GI tract. Sugar alcohols can’t be broken down by the body and absorbed like other foods, so they arrive at the colon mostly intact, pulling water with them, Colleen Tewksbury, Ph.D., R.D., senior research investigator and bariatric program manager at Penn Medicine and president-elect of the Pennsylvania Academy of Nutrition and Dietetics, tells SELF. Bacteria feast on them, causing gas and bloating, which triggers your GI system to try to push through the offending contents as quickly as possible. This can trigger diarrhea in some people, Tewksbury explains.
Plus, coffee and other caffeinated drinks are thought to speed up the rate at which food moves through you, says Dr. Oxentenko.. “Caffeine in and of itself is a gastric stimulant, so it's going to stimulate muscle movement,” explains Tewksbury. And that can bring on the urge to poop.
But pinpointing a dietary cause of the trots can be tricky as triggers are highly personalized. “I know that broccoli is not necessarily always in agreement to me right before a race or an intense run,” says Nader. “Whereas someone else might not be affected at all by broccoli.”
That “someone else” includes MacMahon. “My standard pre-race meal is rice, tofu, cauliflower, and broccoli,” she says. “Now, for some people that would cause huge issues. But that’s what works for me.”
The activity of running itself can also affect gut transit, says Dr. Oxentenko.
In a 2014 review of GI complaints during exercise published in The Journal of Sports Medicine, the authors note that the repetitive gastric jostling that happens when you run can contribute to farting, diarrhea, and urgency (which can be part of having diarrhea, but can occur without it, too). The same review also suggests that one of the main contributors to GI symptoms during intense exercise, especially when folks are are not hydrated properly, is reduced blood flow to the intestine. And the authors also suggest that increased rates of breathing and drinking from water bottles during exercise (of any kind; not running specifically) can cause athletes to swallow more air and thus result in mild to moderate stomach distress.
Experts also believe that both the duration and intensity of your run can impact your chances of GI issues. According to the Mayo Clinic, runner’s diarrhea is most common with long-distance running. And a small 2018 study in the Journal of Sports Science found that the higher intensity runs (among other factors like anxiety and stress) are positively linked to GI distress.
Certain runners may be more prone to experience these, uh, runs.
Runner’s diarrhea can happen to anyone, says Dr. Oxentenko, but some factors may make it more likely to happen. Trying out foods you don't usually eat (or don't usually eat before a run) could increase your likelihood of runner's trots, as could eating/drinking too much fuel before or during your run.
Your chances of getting diarrhea before, during, or after your run could also increase if you take medications like diuretics, which up your chances of fluid loss; you have baseline irregular pooping (think: chronic irritable bowel syndrome or chronic diarrhea); or you have a weak anal sphincter, which could be caused by things like obstetric trauma or previous anal surgery, says Dr. Oxentenko.
Now for the good news: what you can do to minimize the chances of runner’s diarrhea.
On the whole, consider avoiding foods high in fiber or those that are particularly gas-producing in the 24 to 48 hours before a race or long run, suggests Dr. Oxentenko. While you’re running, it could be tricky to know if that uncomfortable feeling is simply a trapped toot or stool-in-the-making, she says, so it’s best to avoid these foods pre-run. You should also skip excess food and drinks that contain sugar alcohols in place of sugar. And if you’re sensitive to caffeine, cut back on that, too, she adds.
The timing of when you eat pre-run is also important, though there’s no one-size-fits-all rule for it. “My general recommendation is to not eat at least an hour before [a run],” says Nader. If you are eating two to three hours before, avoid foods that are high in fat, fiber, and protein and instead opt for simple, easily digested carbohydrates, like a banana, she says.
Fueling while you run? You may want to consume your beverages and/or snacks of choice in small amounts throughout the workout, advises Dr. Oxentenko. If your electrolyte drink upsets your stomach (which, depending on the concentration and volume, can commonly happen, Dr. Oxentenko says), consider diluting it with water, she adds.
Also, you should definitely test out any mid-run fuel before race day to make sure you can tolerate it well. When testing products, it’s a good idea to run at the pace you plan for your race, says MacMahon, who’s a U.S.A.T.F. certified coach level 3 and an I.A.A.F. certified coach level 5.
In terms of hydration, it’s hard to give specific recommendations on how much water you should drink pre and mid-run because so many factors can influence your hydration levels. These factors include the heat, humidity, elevation, and intensity and duration of your exercise as well as your overall health and whether you’re pregnant or breastfeeding, per the Mayo Clinic. But as a generalized guideline, Zeratsky recommends simply drinking when you’re thirsty.
To avoid discomfort and cramps, drink small amounts of water consistently throughout your run, Barbara Lewin, R.D.N., a South Florida-based sports nutritionist who works with elite athletes (including Olympians, Ironman competitors, and ultra-endurance racers), tells SELF.
Also helpful: If you’ve experienced runner’s diarrhea in the past, think about what you ate in the couple days leading up to the run (or during the run itself). Dr. Oxentenko suggests keeping a food diary and noting the days when the trots strike to help spot patterns and identify things that could potentially upset your stomach.
“You’re going to be in the best position to avoid it if you know your body and how your body responds to things,” says MacMahon. “And that takes time and attention.”
But sometimes, despite your best efforts, the trots can strike anyways. Here’s what to do when that happens.
Speaking from personal experience, when the trots come on, they come on fast and with little warning. Unfortunately, once that OMG-where’s-the-nearest-toilet sensation arises, there’s not much (if anything) you can do to make it disappear. But instead of sprinting home in a panic, it’s better to simply stop running.
“This may give someone more control of the urgency compared to if they were continuing to run,” explains Dr. Oxentenko. Another reason to slow down is that running with your cheeks clenched could cause you to alter your form and potentially hurt yourself, says Nader. Once you’ve slowed your pace, do your best to locate the nearest restroom, or—worst case scenario—a discreet place to do your biz.
And if runner’s diarrhea ambushes you mid-run, try not to sweat it, says MacMahon. It sucks, and it’s embarrassing, but it does happen. For further peace of mind in the future, you could consider planning your running routes accordingly to give yourself an easy out—or, in this case, an easily accessible bathroom. Some of MacMahon’s clients will even complete their workouts in loops so that they can get home quickly if needed.
Not all runner’s diarrhea should be shrugged off, though. Here’s when you should see a doctor.
If the trots are sabotaging most of your runs and/or you can’t identify a cause, that’s a sign you should probably see a medical professional about the issue, says Dr. Oxentenko.
Beyond that, there are other instances in which your trots warrant a chat with your doc, according to Dr. Oxentenko: if you have chronic diarrhea even when you’re not running, if there’s any blood in your stool, if you notice any changes in patterns (like, you’re a longtime runner who didn’t used to have a problem with trots till recently), or if you have any kind of abdominal pain or fever. Runner’s diarrhea that fits any of these descriptions may be a sign that you’re actually dealing with an underlying condition, such as inflammatory bowel disease (Crohn’s or ulcerative colitis), celiac disease, microscopic colitis, or irritable bowel syndrome says Dr. Oxentenko.
In rare cases, especially when you’re running really long, dehydration can trigger a condition called ischemic colitis. This occurs when blood is shunted away from your colon to muscles and other vital organs, and causes severe abdominal cramps and bloody stool along with the diarrhea, says Dr. Oxentenko. Diarrhea that comes on severely or suddenly could also be a sign of an infection or a reaction/side effect to a medication, she adds.
To sum it up: shit happens.
With a little trial and error and a lot of paying attention to your body, hopefully you can figure out what works for you. And if you can’t get to the bottom of the issue and/or it’s accompanied by other worrisome symptoms, definitely see a doctor.
After all, your ultimate goal should be to enjoy running for all of its wonderful perks while minimizing the (literal) crap.
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