Let’s just enter the confessional booth here one at a time. It’s happened to all of us: you’re blissfully running along enjoying your workout, or maybe even running a race, when it strikes.
No, we aren’t referring to a second wind, burst of energy, or the elusive runner’s high. This is the uninvited guest—or, more appropriately, uninvited pest—known as runner’s trots or runner’s diarrhea.
Sudden cramping and abdominal pain and, yes, the urge to find the toilet imminently.
As runner’s trots is a very common occurrence, at least one time or another almost every runner has had to dodge into a shop to use the bathroom or dart into the nearby woods to find cover to relieve themselves.
But is this avoidable?
In this guide, we will discuss what causes runner’s trots and our best 12 tips for preventing digestive issues and gastrointestinal problems while you are out on your runs.
What Is Runner’s Trots?
Runner’s trots, also called runner’s diarrhea, refers to acute diarrhea induced by exercise.
Of course, while diarrhea can occur at any time and from numerous factors, running itself (or certain other forms of exercise) can be a causative factor. Thus, the terms runner’s trots and runner’s diarrhea were coined to specifically denote diarrhea caused by running.
In fact, runner’s diarrhea is such a common phenomenon that scientific studies have even been designed to specifically examine what causes diarrhea in runners.
Symptoms of runner’s trots include urgency to defecate mid-run or shortly after running, loose bowel movements, and abdominal cramps and gas.
Although it’s not a pathological condition, runner’s diarrhea can certainly impact performance.
How Common Is Runner’s Diarrhea?
So, how common is it to have diarrhea from running, or worse, diarrhea while running?
The short answer is that runner’s trots is extremely common. An upset stomach can strike runners of any age, sex, fitness level, or years of experience.
Even elite and professional runners have notoriously fallen prey to runner’s trots on some of their biggest race stages and televised performances.
For example, superstar runner and former women’s marathon world record holder Paula Radcliffe battled angry bowels during the 2005 London Marathon and had to stop briefly with just four miles to go to use the toilet.
Other elite runners haven’t been as lucky with the timing of their bathroom breaks, and the evidence of their intestinal distress is all too visible to the still awe-inspired spectators.
Everyday runners aren’t immune, either.
For example, one study1Parnell, J. A., Wagner-Jones, K., Madden, R. F., & Erdman, K. A. (2020). Dietary restrictions in endurance runners to mitigate exercise-induced gastrointestinal symptoms. Journal of the International Society of Sports Nutrition, 17(1). https://doi.org/10.1186/s12970-020-00361-w that surveyed 388 runners about their pre-race dietary restrictions and gastrointestinal symptoms found that 22% of the runners noted the urge to defecate while running, along with other stomach issues like stomach pain/cramps (42%), intestinal pain/discomfort (23%), side ache/stitch (22%), and bloating (20%).
Another study2Sullivan, S. N., & Wong, C. (1992). Runners’ diarrhea. Different patterns and associated factors. Journal of Clinical Gastroenterology, 14(2), 101–104. https://doi.org/10.1097/00004836-199203000-00005 that surveyed 109 long-distance runners about their bowel function related to running found that a whopping 62% of runners had stopped to make a bowel movement during a run.
Worse, 12% of the runners had experienced fecal incontinence while running, 43% had “nervous” diarrhea before a race, and 12% had stopped mid-race to use the toilet.
Also, runner’s diarrhea doesn’t have to strike during the run itself; runner’s trots can also refer to acute diarrhea shortly after running. Another 47% of the surveyed runners noted experiencing diarrhea after racing or hard runs.
Still, another study3Riddoch, C., & Trinick, T. (1988). Gastrointestinal disturbances in marathon runners. British Journal of Sports Medicine, 22(2), 71–74. https://doi.org/10.1136/bjsm.22.2.71 of 471 runners in the Belfast City Marathon found that 83% of the respondents had either occasionally or frequently suffered one or more GI disturbances during or immediately after running.
Of these, the urge to have a bowel movement (53%) and diarrhea (38%) were among the most common complaints, especially among female runners (74% and 68% respectively).
Clearly, suffering from runner’s trots is not a rare occurrence.
What Causes Runner’s Trots?
There are several potential causes of runner’s trots, and most research suggests4de Oliveira, E. P. (2017). Runnerʼs diarrhea. Current Opinion in Gastroenterology, 33(1), 41–46. https://doi.org/10.1097/mog.0000000000000322 that ultimately, runner’s diarrhea is caused by an interplay of one or more ischemic, mechanical, and nutritional factors.
The following are the primary factors that increase the risk of runner’s trots:
#1: Mechanical Jostling
The repetitive up-and-down motion of running itself can jostle the bowels and stimulate them, causing diarrhea while running.
#2: Reduced Blood Flow to the GI Tract
When you run, the body diverts blood away from the digestive tract to profuse your working muscles.
As a result, digestion slows.
Any undigested food can act as an irritant to the intestinal lining while it sits around without progressing forward.
To expunge this perceived irritant, the body may force rapid bowel transit, causing you to rush to the bathroom during a training run or race.
#3: Adrenaline
When you start to run, the sympathetic nervous system stimulates your heart and breathing rates.
Adrenaline surges in the bloodstream, increasing the contractions in your colon.
#4: Dehydration
Hydration can slow the gastric emptying rate, leaving undigested food in the stomach if you go running too soon after eating.
Additionally, if you’re dehydrated, your stomach tries to compensate for the lack of fluid in the body by retaining water, which can trigger the urge to use the bathroom.
#5: Caffeine
Caffeine is a stimulant, and it can also be an irritant to the stomach and intestines.
Even without running, many runners are sensitive to caffeine and will notice that that beloved cup of coffee stimulates a bowel movement.
#6: Anxiety
If you’ve ever noticed a correlation between getting runner’s trots on race day or when you have a hard workout, there’s a good chance that anxiety is contributing to your bowel troubles.
Anxiety is known to cause a host of gastrointestinal symptoms5Haug, T. T., Mykletun, A., & Dahl, A. A. (2002). Are Anxiety and Depression Related to Gastrointestinal Symptoms in the General Population? Scandinavian Journal of Gastroenterology, 37(3), 294–298. https://doi.org/10.1080/003655202317284192 including diarrhea.
Pre-race jitters and nerves about a long run or difficult workout can certainly contribute to getting a runner‘s diarrhea.
#7: Nutrition Timing
Eating too soon before you go running can also cause runner’s diarrhea.
Eating initiates the gastrocolic reflex, which provokes the urge to empty your bowels.
Essentially, when you eat, your stomach walls stretch. This stimulates the release of digestive enzymes in the small intestines to prepare to digest food.
This further relays a signal to the colon that more digestive products will arrive, so the bowels respond by “making room” for the imminent bolus of undigested foodstuffs.
The colon reacts by triggering strong, peristaltic contractions to propel the remaining undigested waste out as feces, even if it wasn’t yet in the bowels.
It can often take at least 30-50 minutes6Snape. (2021). The gastrocolic response: evidence for a neural mechanism. Gastroenterology, 77(6). https://pubmed.ncbi.nlm.nih.gov/583043/ for the gastrocolic reflex to kick in, and upwards of 70 minutes if the meal was high in fat.
Therefore, if you eat a snack or meal before you run but don’t wait long enough for the inevitable defecation, you might find that you’re running for the nearest bathroom to poop mid-workout.
#8: Food Choices
What you eat before you run significantly impacts how your gut will feel during your workout.
High-fiber foods, high-fat food, sugar, or sugar alcohols can cause digestive distress, as can foods high in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs), such as onions, garlic, and cauliflower.7de Oliveira, E. P. (2017). Runnerʼs diarrhea. Current Opinion in Gastroenterology, 33(1), 41–46. https://doi.org/10.1097/mog.0000000000000322
Moreover, if you eat foods you are sensitive to—such as dairy if you are lactose intolerant or gluten—you can count on an unplanned bathroom break.
What Are the Best Ways To Prevent Runner’s Trots?
While dealing with an occasional urge to use the toilet while running is probably inevitable, you can reduce the risk of runner’s trots derailing your workout by adjusting your routine.
Here are some tips to prevent runner’s trots:
#1: Use the Toilet First
This one is obvious: Ensure you’ve used the bathroom and tried to empty your bowels before you hit the road for your run.
#2: Drink Enough Water
Dehydration contributes to GI upset during exercise, so ensure you’re hydrating enough before and during your runs.
Use electrolyte beverages for runs longer than 60 minutes or if you’re a heavy sweater.
#3: Wait Longer to Run
Be mindful of giving your digestive tract ample time to digest your pre-run snack. Try to wait at least an hour after eating to run (or until you’ve used the bathroom).
#4: Identify Your Trigger Foods
Examining your diet and eliminating foods that trigger diarrhea is probably the single best way to reduce the risk of runner’s trots.
If you frequently experience runner’s diarrhea, keep a food diary along with your training log to identify patterns and problematic foods.
Then, eliminate them and see how you do.
#5: Reduce Fiber and FODMAPs
While eating vegetables and legumes is certainly healthy and should be encouraged for all runners, fibrous foods and foods high in FODMAPs are known to stimulate the GI tract.
#6: Hold the Caffeine
If you’re sensitive to caffeine, avoid coffee, caffeinated energy gels, caffeinated running gum, or energy drinks before or during your run.
#7: Cut Out Artificial Sweeteners
Not only are they non-nutritive, but artificial sweeteners and sugar alcohols are also significant irritants to the GI tract.
However, many pre-workout drinks for runners, energy bars, protein bars, and other sports beverages contain artificial sweeteners as a way to cut calories.
Read the label to check the ingredients before you “fuel” with something that won’t help your body and will send you running for the toilet.
#8: Be Wise About Your Energy Gels and Sports Drinks
A scientific review suggested that ingesting several different types of carbohydrates in tandem, rather than glucose alone, during your run can potentially reduce the risk of runner’s trots.
#9: Try a Probiotic
There’s also some evidence to suggest8Morishima, S., Aoi, W., Kawamura, A., Kawase, T., Takagi, T., Naito, Y., Tsukahara, T., & Inoue, R. (2021). Intensive, prolonged exercise seemingly causes gut dysbiosis in female endurance runners. Journal of Clinical Biochemistry and Nutrition, 68(3), 253–258. https://doi.org/10.3164/jcbn.20-131 that running can cause gut dysbiosis and disturb the healthy gut bacteria you need to properly digest your food.
This can increase the risk of diarrhea.
A high-quality probiotic supplement may help restore balance to your gut microbiome and improve gut health overall.
#10: Practice Your Fueling
To some degree, the digestive tract adapts over time to get used to the jostling of running and the need to simultaneously digest the fuel you are taking in during your workout.
Be patient as you adjust.
Once you find something that works, stick with it to reduce the risk of runner’s trots on race day.
#11: Wear Looser Running Clothes
It sounds silly, but some experts say that tight running clothes like leggings, compression shorts, and form-fitting tops that compress the abdomen can increase the risk of diarrhea while running.
#12: Stay Relaxed
Stress and anxiety can summon the bowels to get moving, so try to keep pre-race jitters at bay and implement relaxation techniques before and during your runs.
Remember to stick to bland, easy-to-digest foods, such as simple carbs, on race day and before long runs to keep your digestive system calm.
And hey, if runner’s diarrhea does strike, you’re in good company. It happens to almost every runner at least once or twice.
Meeting with a sport’s nutritionist is a great way to devise a specific eating plan for your needs and restrictions.
If you are also experiencing pain, checking with your healthcare provider can help discover the underlying cause, whether it be ischemic colitis, irritable bowel syndrome (IBS), etc.
If you are looking to work on your pre-race meals, check out this next guide:
I suffered a lot over many years with this condition and I tried pretty much all the tips suggested here, with varying degrees of success but I wasn’t able to really get on top of the problem until my doctor recommended that I try taking anti-histamines. Bingo! Result, with almost overnight success. Now I take a mild anti-histamine most (but not all) evenings and certainly before a long run the next morning. I don’t have any any side-effects and they are non-addictive. If you’re interested to learn more, look up the research on the topic done by KU Leuven university in Belgium. For me, it’s been a simple but transformative change, making me much more confident and able to plan my runs accordingly.
Br, Simon
Simon,
That’s awesome, thanks for sharing your experience and learning here, as well as referencing the research there.
Have a great week,
Thomas from Marathon Handbook
I am at my wits end, and about to give up running. My runners trots are getting worse and worse. I can’t run for more than a mile now without needing to suddenly go and this just continues for the duration of the run. I’ve tried loperamide (starting to build up a few days before), buscopan (for IBS – I don’t have a diagnosis but thought it might help), and lansoprazole for GERD. I avoid caffeine, and don’t use gels. Still I have this awful problem. Any advice? I’m desperate and often desperate!!