Runner’s Trots: More Common Than You Thought

Uh oh… feeling like you gotta go? You’re not alone. Read up on trusted advice from doctors and runners on what to do with mid-run poos.

You’ve finally found your stride, achieved that perfect pace that’s about to carry you from mile 3 to mile 25… until BAM! You’re hit with an intensely abrupt rumble and tumble in your tummy.

It’s not a matter of if you have to go to the bathroom, but where—and when. 15 seconds? Maybe 20?

If this sounds at all familiar, you’ve more than likely experienced the ever-glorious runner’s colitis, runner’s diarrhea, or runner’s trots as it’s colloquially known.

We’ve got the low down on how to slow down your bowel movements—without cutting too deep into your running performance.

Have a specific question in mind? Click on a link below to get your (ahem, urgent) answers or read your way through to learn all about runner’s diarrhea and how to prevent it from striking at the worst possible time.

What is runner’s diarrhea?

It goes by many names: formally runner’s colitis, generally runner’s diarrhea, or casually runner’s trots.

Ultimately, whatever euphemism you choose still refers to the same condition—the experience of a sudden and urgent loose bowel movement during or after a run.

So what are the symptoms of runner’s diarrhea? Oh, if you’ve ever been that pooping runner tucked behind the bushes, you very well know.

But actual diarrhea is only one symptom of runner’s trots or runner’s colitis (not to be mistaken with ulcerative colitis, which affects both athletes and sedentary folks alike).

Additional symptoms of runner’s trots include:

  • Intestinal cramping
  • Gas or bloating
  • Nausea
  • Acid reflux

If you’ve experienced these less-than-pleasant sensations, watch out—the next time you take off it could develop into full blown (excuse the imagery) runner’s diarrhea, whether it’s during your marathon or morning jog.

What causes runner’s diarrhea?

Similar to other gastrointestinal (GI) tract symptoms, doctors have yet to pin down an exact cause of runner’s diarrhea—but they do have some pretty strong theories.


Ischemia, or the restriction of blood flow, caused by dehydration is one of the leading theories.

When you run, you lose a ton of your body’s water content via perspiration. As hydration levels sink and dehydration sets in, the water volume in the blood stream takes a serious dive.

Now this is problematic for a few reasons: one, H2O assists with the delivery of red blood cells and essential nutrients to tissues, muscles, and organs (including your gut) which help them operate at their peak performance.

While you’re intensely exercising under aerobic duress, most of these blood cells are redirected to the muscles in overdrive who need the most help—and away from “less critical” organs, A.K.A. your large intestine.

Cathy Fieseler, M.D., suggests, “Runner’s colitis is thought to be due to compromised blood flow to the intestines during exercise”. But’s that’s only one possible explanation.

Stress and anxiety

Nervous runner’s diarrhea is also a thing. As Harvard Health discusses, the gut-brain connection is “no joke”. If a situation has ever made you felt nervous, or you’ve ever experienced “butterflies in your stomach”, you know what we’re talking about.

Your GI tract is extremely sensitive to emotion, including not only stress and anxiety, but also elation, anger, excitement, and so on.

On the day of the big race, it’s possible that intense emotions can trigger unpleasant reactions in your gut—including the constriction of bowels, leading to runner’s diarrhea.

Hormone fluctuation

Even if you’re cool as a cucumber, not nervous at all before a race, hormone fluctuations induced by exercise can have the same effect.

Distance runners in particular go through a variety of metabolic changes as their bodies push themselves, and “sorting through the quagmire of chemical changes is staggering”. These changes in the gut can explain not only runner’s trots, but also the nausea, acid reflux, and cramping frequently described.

Raised body temperature

Heat makes all of this worse. Whether you’re running in the desert or in the rain, your body temperature is on the rise alongside your heart rate, warming up your internal contents and sort of melting them, so to speak.

When coupled with low blood pressure due to running dehydration, your sphincter has a more difficult time retaining the loosened stool, which creates the urgent sensation to go.

Decelerating force

Lastly, take all the above possible causes of runner’s diarrhea and combine them with the decelerating force of your foot hitting the ground with each strike.

Every time you move up and down, you shake up your intestinal contents—or, as Anna Rothschild visually compares to a creating “a poop milkshake in your gut with every bounce”. Yikes.

The emulsifying effect puts pressure on your colon (hence the lovely nickname of a “colon blow”), making you feel like you need to go… and you need to go now.

Who gets runner’s diarrhea?

Anyone’s susceptible to becoming a pooping runner—it happen to the best of us. In fact, a study published in the Journal of Clinical Gastroenterology found that a whopping 62 percent of runners had to stop while training to have a bowel movement!

Their study—consisting of 109 distance runners who completed a questionnaire—found much more than that:

  • 12% had fecal inconsistency while running
  • 43% had nervous runner’s diarrhea before a competition
  • 47% had diarrhea after long runs
  • 16% had blood in their stool after the same situation

The results go to show that runner’s trots are incredibly—and unfortunately—very common. They also found no correlation between age and runners’ food allergies… meaning anyone involved in long distance running should be prepared for runner’s diarrhea to strike at any time, pre-run, post-run, or mid-run.

Pro tip: Unless you’d prefer a leaf, bring along a wet wipe just in case.

How long does runner’s diarrhea last?

So you’ve been hit with the runner’s trots, or you’re trying to desperately avoid them? Don’t panic; as noted, stress will only make your situation worse.

If you’re not near a Porta-Potty or public restroom, pull off your trail to a discrete location, dig a hole to the best of your ability, and wait for your bowel movement to pass. Be sure to be courteous and respectful by cleaning up after yourself once you’re done—even if it cuts into your PR.

Best advice: Pick a route with plenty of pit stops.

Those who experience runner’s diarrhea after a long run, should feel relief within 24 hours tops.

If your runner’s colitis symptoms last longer than that, it might be time to see a doctor. Same with heart palpitations, dizziness, and bloody/black stool—those are all red flags of a more serious condition beyond basic running health.

Keep a food and training log so you can track how your runner’s diet might affect your athletic performance and, if necessary, give your physician some much needed detail for the best diagnosis and treatment method.

How to prevent runner’s diarrhea?

Runner’s colitis typically affects long distance runners more so than short sprinters; to avoid getting the trots, take your time training and slowly building up your mileage by following the golden 10% rule.

As you start to push the distance, remember to bring the necessary “surprise” supplies, as well as taking additional measures to prevent runner’s diarrhea.

Stay hydrated

Heat and hydration are opposite foes, but whether it’s hot or not, it’s important to drink, drink, drink plenty of water.

Avoid pain medicine

Not all pain medicines are one in the same, but non-steroidal anti-inflammatory drugs (NSAIDs) should be high on your radar; evidence suggests that increased use of NSAIDs by endurance runners may contribute to runner’s colitis.

Stay away from over-the-counter medicines like ibuprofen and stick to those ice baths and foam rollers instead.

Improve your runner’s diet

Not only should you avoid NSAIDs, but certain foods should also be kept off your list, especially within three hours before a long distance race:

  • Lactose and dairy products
  • High-fiber foods
  • High-fat foods
  • Artificial sweetener

If possible, try to avoid eating two to three hours before the race and watch your carbohydrate intake whenever you refuel during runs.

Go before your run

Sounds like common sense, but try to evacuate yourself fully before taking off for a long ride. Aim to choose a route with plenty of available restrooms as you amp up your training, and eat the right food for runners to make your tummy happy.

Talk to your doctor

If runner’s colitis is a problem that persists—despite training logs, ample water, and an optimized runner’s diet—it might be time to have a conversation with your doctor.

They might be able to prescribe medicine that slows down your bowel movements, or they might identify an alternative GI diagnosis and treatment plan.

Runner’s diarrhea is definitely not ideal, whether it’s before, after, or—worst of all—during your run. Take these considerations to mind and avoid falling victim to one of runners’ worst nightmares.

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