Preventing Workout Diarrhea During and After Exercise

Do you have problems with loose stools or diarrhea during or after a workout? This is so common that it has a cute name, runner's trots. Walking and running are good exercises for maintaining regular bowel movements. This is one theory on why there is a decreased incidence of colon cancer among those who walk and run. However, they can also be too much of a good thing.

Causes of Diarrhea During or After Workouts

No single cause of exercise-related diarrhea has been definitively identified. Runner's trots may be caused by different factors in different people. One theory is that the simple up and down jostling of the body stirs the bowels. Blood flow to the intestines is diverted to your legs during walking and running and that may contribute to the cramping and diarrhea.

Underlying irritable bowel disease may be brought to light by the additional stress of exercise. Dehydration on long walks and runs can also cause diarrhea. Lactose intolerance effects might be enhanced by the exercise.

You're Not Alone

An estimated 20 to 50 percent of distance runners have runner's trots, with a range of symptoms from cramping and nausea to bouts of flatulence and diarrhea during or after their workout. Walkers, especially those who walk briskly at a high heart rate, can discover this same effect.


You may experience any of these symptoms: cramping, nausea, flatulence, or diarrhea during or after your workout. It can produce painful cramping and an extremely urgent need to defecate.


Use these do's and don'ts to reduce your bouts of runner's trots and exercise-related loose stools.


  • Avoid caffeine and warm fluids as they can speed up the movement of wastes through the intestines.

  • Limit dairy products or use Lactaid when enjoying dairy products, especially if you know you're lactose-intolerant.

  • Drink plenty of fluids. It's best to drink a full 16 ounces of water an hour before your workout, giving the excess fluid time to pass through. Drink 8 ounces of water every 15 minutes while walking, running, or doing a workout.

  • Know your bowel habits and try to schedule your workouts for immediately after your usual bowel movement time. You may want to start keeping notes if you haven't previously paid attention to this.

  • Use low-residue diet tips the day before a race or long walk. This focuses on food that's low in fiber, such as white bread products and eggs.


  • Eat less than two hours before your workout. The presence of food in your stomach may make things worse or set off the symptoms.

  • Fill upon high-fiber foods in the days before a long race. Save the beans and roughage for future healthy meals.

  • Eat any foods that you know produce flatulence or loose stools for you. There are some that are common, but others may be specific for you.

  • Be unprepared. Design your walking and running routes to include a restroom stop at the time when diarrhea usually hits (say, half an hour into your run).

  • Forget plan B. If all other precautions fail or you know toilets will not be readily available, use an OTC anti-diarrhea product such as Imodium. Studies have shown the drug reduced exercise-induced diarrhea in 70 percent of triathletes prone to it.

When to See the Doctor

While runner's trots are common, this is a symptom to discuss with your doctor at your next checkup. If you encounter it frequently and you have other digestive symptoms, make an appointment to have these issues checked. It might be a sign of inflammatory bowel syndrome or other functional digestive disorders.

While the details might be embarrassing, you will only get a good diagnosis by giving a full and frank history. Keep notes on your episodes of runner's trots so you will have good data to give your doctor.

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Article Sources

  1. Wolin KY, Patel AV, Campbell PT, et al. Change in Physical Activity and Colon Cancer Incidence and Mortality. Cancer Epidemiol Biomarkers Prev. 2010;19(12):3000-4. doi:10.1158/1055-9965.EPI-10-0764

  2. De oliveira EP, Burini RC, Jeukendrup A. Gastrointestinal Complaints During Exercise: Prevalence, Etiology, and Nutritional Recommendations. Sports Med. 2014;44 Suppl 1:S79-85. doi:10.1007/s40279-014-0153-2

  3. What Is Inflammatory Bowel Disease? Centers for Disease Control and Prevention. 2018.

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