Table of ContentsView AllTable of ContentsSymptomsCausesPreventionRelated Conditions
Table of ContentsView All
View All
Table of Contents
Symptoms
Causes
Prevention
Related Conditions
Runner’s diarrhea, also sometimes referred to as “runner’s trots,” is the sudden onset ofdiarrheathat occurs during or immediately after high-intensity exercise. It is a condition commonly associated with long-distance running but can happen with any intense physical exercise.
Runner’s diarrhea is thought to be due to physiological changes that occur when the body is overtaxed. Diet and certain underlying medical conditions, likeirritable bowel syndrome (IBS), may increase the risk.
Runner’s diarrhea is rarely serious but can lead to severedehydrationif left untreated. Changes in diet and workout habits can help prevent flare-ups.
This article describes the symptoms and causes of runner’s diarrhea, including medical conditions that may contribute. It also offers simple tips on how to prevent it.
Sam Edwards / Caiaimage / Getty Images
Symptoms of Runner’s Diarrhea
Runner’s diarrhea refers to frequent, loose bowel movements that occur during or immediately after running or other extreme physical activities.
Runner’s Diarrhea or Heat Stroke?The symptoms of runner’s diarrhea are similar to that ofheat exhaustion or heat strokein which the bowel will suddenly lose control of its contents. Both typically occur when the body is overheated, but with runner’s diarrhea, there won’t be a sudden, severe fever or vomiting that is characteristic of heat stroke.
Runner’s Diarrhea or Heat Stroke?
The symptoms of runner’s diarrhea are similar to that ofheat exhaustion or heat strokein which the bowel will suddenly lose control of its contents. Both typically occur when the body is overheated, but with runner’s diarrhea, there won’t be a sudden, severe fever or vomiting that is characteristic of heat stroke.
Causes of Runner’s Diarrhea
Runner’s diarrhea is thought to involve ischemic, mechanical, and nutritional factors that together cause the spontaneous onset of diarrhea during or following exercise.
Ischemic Causes
Ischemiadescribes the sudden loss of blood flow to tissues. With runner’s diarrhea, this happens when intense exercise diverts blood from the intestines to the muscles of the legs which need more oxygen to perform.
The loss of blood can lead toischemic colitisin which the colon suddenly becomes inflamed, causing the excessive release of fluids into the intestines. Colitis also increases contractions of smooth muscles that move stool through the intestine. Both of these factors contribute to diarrhea.
Mechanical Causes
Studies have shown that running for 90 minutes at a challenging pace—as one might for a marathon—temporarily increases the permeability of the intestines.Also known as"leaky gut,“this occurs when the spaces between cells in the lining of your intestines become wider, allowing fluids and nutrients to seep into your colon.
Extreme physical exercise also releases a stress hormone calledcortisolwhich triggers changes in digestion and absorption that can lead to loose stools or diarrhea.
Nutritional Causes
Runner’s diarrhea is believed to be strongly associated with certain foods or dietary habits, although no single pattern has yet been found.
Certain food intolerances may increase a person’s risk of runner’s diarrhea, such aslactose intoleranceorgluten intolerance.It is well known that exercise can induce changes that make conditions like gluten intolerance worse.
Some experts believe that short-chain sugars calledFODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols)may predispose a person to runner’s diarrhea. This is because FODMAPs are harder to break down and can ferment in the colon, causing gas, bloating, and diarrhea. Even so, not every athlete who eats FODMAPs gets runner’s diarrhea.
Other experts contend that caffeine can lead to runner’s diarrhea due to its mild laxative effect. When paired with increased body temperature, the laxative effect may be intensified.
Overhydrating can also potentiate diarrhea. When you drink too much liquid, the kidneys can’t remove it fast enough and will move it to the intestines. This is especially true when consuming sports drinks that are often high in sugar or artificial sweeteners (both of which contribute to diarrhea).
Preventing Runner’s Diarrhea
Several factors can increase the movement of your intestine (known asperistalsis) and the release of fluids from intestinal tissues. By mitigating these factors, you may reduce your risk of runner’s diarrhea.
Not every intervention will work for everyone, and it may require a process of trial and error to find the solution that is right for you.
Dietary Changes
There is no single diet that can help everyone with runner’s diarrhea, but here are some of the more common interventions to consider:
Medications to Avoid
Some medications can induce diarrhea, particularly with intense exercise. These include:
Workout Changes
Certain simple changes to your workout routine can potentially reduce the risk of runner’s diarrhea. Among these:
There are certain medical conditions that may increase your risk of runner’s diarrhea. Treating or managing these conditions may help reduce the risk.
Irritable Bowel Syndrome (IBS)
These include:
Nervous Diarrhea
Summary
Runner’s diarrhea is the sudden onset of diarrhea during or after extreme physical activity, such as long-distance running. It is thought to be related to a combination of mechanical, dietary, and ischemic risk factors that increase intestinal contractions and fluid release.
Avoiding fatty or spicy food, caffeine, dairy, sugar, artificial sweeteners, or NSAIDs prior to a workout may reduce the risk of runner’s diarrhea. Adjusting the intensity of your workouts, wearing lighter clothes, and avoiding overhydration may also help.
14 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.De Oliveira EP.Runner’s diarrhea: what is it, what causes it, and how can it be prevented?Curr Opin Gastroenterol.2017 Jan;33(1):41-46. doi:10.1097/MOG.0000000000000322Centers for Disease Control and Prevention.Warning signs and symptoms of heat-related illness.Faress A, Masood S, Mian A.‘Runs’ from a run: a case of exercise induced ischemic colitis.World J Emerg Med. 2017;8(4):302-304. doi:10.5847/wjem.j.1920-8642.2017.04.010FitzGerald JF, Hernandez III LO.Ischemic colitis.Clin Colon Rectal Surg.2015 Jun;28(2):93–98. doi:10.1055/s-0035-1549099Karhu E, Forsgard RA, Alanko L, et al.Exercise and gastrointestinal symptoms: running-induced changes in intestinal permeability and markers of gastrointestinal function in asymptomatic and symptomatic runners.Eur J Appl Physiol.2017;117(12):2519–2526. doi:10.1007/s00421-017-3739-1Camilleri M.The leaky gut: mechanisms, measurement and clinical implications in humans.Gut. 2019;68(8):1516-1526. doi:10.1136/gutjnl-2019-318427Sharma N, Bhatia S, Chunduri V, et al.Pathogenesis of celiac disease and other gluten related disorders in wheat and strategies for mitigating them.Front Nutr.2020;7:6. doi:10.3389/fnut.2020.00006Armstrong LE.Rehydration during endurance exercise: challenges, research, options, methods.Nutrients.2021 Mar;13(3):887. doi:10.3390/nu13030887Erdman KA, Jones KW, Madden RF, Gammack N, Parnell JA.Dietary patterns in runners with gastrointestinal disorders. Nutrients. 2021;13(2):448. doi:10.3390/nu13020448Phillip NA, Ahmed N, Pitchumoni CS.Spectrum of drug-induced chronic diarrhea.J Clin Gastroenterol. 2017 Feb;51(2):111-117. doi:10.1097/MCG.0000000000000752National Institute of Diabetes and Digestive and Kidney Diseases.Definition & facts for irritable bowel syndrome.International Foundation for Gastrointestinal Disorders.IBS diet.Kim JY, Lim MH.Psychological factors to predict chronic diarrhea and constipation in Korean high school students.Medicine (Baltimore).2021 Jul 9;100(27) e26442. doi:10.1097/MD.0000000000026442Yang J, Fox M, Cong Y, Chu H, Zheng X, Long Y, Fried M, Dai N.Lactose intolerance in irritable bowel syndrome patients with diarrhoea: the roles of anxiety, activation of the innate mucosal immune system and visceral sensitivity.Aliment Pharmacol Ther. 2014;39(3):302-11. doi:10.1111/apt.12582
14 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.De Oliveira EP.Runner’s diarrhea: what is it, what causes it, and how can it be prevented?Curr Opin Gastroenterol.2017 Jan;33(1):41-46. doi:10.1097/MOG.0000000000000322Centers for Disease Control and Prevention.Warning signs and symptoms of heat-related illness.Faress A, Masood S, Mian A.‘Runs’ from a run: a case of exercise induced ischemic colitis.World J Emerg Med. 2017;8(4):302-304. doi:10.5847/wjem.j.1920-8642.2017.04.010FitzGerald JF, Hernandez III LO.Ischemic colitis.Clin Colon Rectal Surg.2015 Jun;28(2):93–98. doi:10.1055/s-0035-1549099Karhu E, Forsgard RA, Alanko L, et al.Exercise and gastrointestinal symptoms: running-induced changes in intestinal permeability and markers of gastrointestinal function in asymptomatic and symptomatic runners.Eur J Appl Physiol.2017;117(12):2519–2526. doi:10.1007/s00421-017-3739-1Camilleri M.The leaky gut: mechanisms, measurement and clinical implications in humans.Gut. 2019;68(8):1516-1526. doi:10.1136/gutjnl-2019-318427Sharma N, Bhatia S, Chunduri V, et al.Pathogenesis of celiac disease and other gluten related disorders in wheat and strategies for mitigating them.Front Nutr.2020;7:6. doi:10.3389/fnut.2020.00006Armstrong LE.Rehydration during endurance exercise: challenges, research, options, methods.Nutrients.2021 Mar;13(3):887. doi:10.3390/nu13030887Erdman KA, Jones KW, Madden RF, Gammack N, Parnell JA.Dietary patterns in runners with gastrointestinal disorders. Nutrients. 2021;13(2):448. doi:10.3390/nu13020448Phillip NA, Ahmed N, Pitchumoni CS.Spectrum of drug-induced chronic diarrhea.J Clin Gastroenterol. 2017 Feb;51(2):111-117. doi:10.1097/MCG.0000000000000752National Institute of Diabetes and Digestive and Kidney Diseases.Definition & facts for irritable bowel syndrome.International Foundation for Gastrointestinal Disorders.IBS diet.Kim JY, Lim MH.Psychological factors to predict chronic diarrhea and constipation in Korean high school students.Medicine (Baltimore).2021 Jul 9;100(27) e26442. doi:10.1097/MD.0000000000026442Yang J, Fox M, Cong Y, Chu H, Zheng X, Long Y, Fried M, Dai N.Lactose intolerance in irritable bowel syndrome patients with diarrhoea: the roles of anxiety, activation of the innate mucosal immune system and visceral sensitivity.Aliment Pharmacol Ther. 2014;39(3):302-11. doi:10.1111/apt.12582
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
De Oliveira EP.Runner’s diarrhea: what is it, what causes it, and how can it be prevented?Curr Opin Gastroenterol.2017 Jan;33(1):41-46. doi:10.1097/MOG.0000000000000322Centers for Disease Control and Prevention.Warning signs and symptoms of heat-related illness.Faress A, Masood S, Mian A.‘Runs’ from a run: a case of exercise induced ischemic colitis.World J Emerg Med. 2017;8(4):302-304. doi:10.5847/wjem.j.1920-8642.2017.04.010FitzGerald JF, Hernandez III LO.Ischemic colitis.Clin Colon Rectal Surg.2015 Jun;28(2):93–98. doi:10.1055/s-0035-1549099Karhu E, Forsgard RA, Alanko L, et al.Exercise and gastrointestinal symptoms: running-induced changes in intestinal permeability and markers of gastrointestinal function in asymptomatic and symptomatic runners.Eur J Appl Physiol.2017;117(12):2519–2526. doi:10.1007/s00421-017-3739-1Camilleri M.The leaky gut: mechanisms, measurement and clinical implications in humans.Gut. 2019;68(8):1516-1526. doi:10.1136/gutjnl-2019-318427Sharma N, Bhatia S, Chunduri V, et al.Pathogenesis of celiac disease and other gluten related disorders in wheat and strategies for mitigating them.Front Nutr.2020;7:6. doi:10.3389/fnut.2020.00006Armstrong LE.Rehydration during endurance exercise: challenges, research, options, methods.Nutrients.2021 Mar;13(3):887. doi:10.3390/nu13030887Erdman KA, Jones KW, Madden RF, Gammack N, Parnell JA.Dietary patterns in runners with gastrointestinal disorders. Nutrients. 2021;13(2):448. doi:10.3390/nu13020448Phillip NA, Ahmed N, Pitchumoni CS.Spectrum of drug-induced chronic diarrhea.J Clin Gastroenterol. 2017 Feb;51(2):111-117. doi:10.1097/MCG.0000000000000752National Institute of Diabetes and Digestive and Kidney Diseases.Definition & facts for irritable bowel syndrome.International Foundation for Gastrointestinal Disorders.IBS diet.Kim JY, Lim MH.Psychological factors to predict chronic diarrhea and constipation in Korean high school students.Medicine (Baltimore).2021 Jul 9;100(27) e26442. doi:10.1097/MD.0000000000026442Yang J, Fox M, Cong Y, Chu H, Zheng X, Long Y, Fried M, Dai N.Lactose intolerance in irritable bowel syndrome patients with diarrhoea: the roles of anxiety, activation of the innate mucosal immune system and visceral sensitivity.Aliment Pharmacol Ther. 2014;39(3):302-11. doi:10.1111/apt.12582
De Oliveira EP.Runner’s diarrhea: what is it, what causes it, and how can it be prevented?Curr Opin Gastroenterol.2017 Jan;33(1):41-46. doi:10.1097/MOG.0000000000000322
Centers for Disease Control and Prevention.Warning signs and symptoms of heat-related illness.
Faress A, Masood S, Mian A.‘Runs’ from a run: a case of exercise induced ischemic colitis.World J Emerg Med. 2017;8(4):302-304. doi:10.5847/wjem.j.1920-8642.2017.04.010
FitzGerald JF, Hernandez III LO.Ischemic colitis.Clin Colon Rectal Surg.2015 Jun;28(2):93–98. doi:10.1055/s-0035-1549099
Karhu E, Forsgard RA, Alanko L, et al.Exercise and gastrointestinal symptoms: running-induced changes in intestinal permeability and markers of gastrointestinal function in asymptomatic and symptomatic runners.Eur J Appl Physiol.2017;117(12):2519–2526. doi:10.1007/s00421-017-3739-1
Camilleri M.The leaky gut: mechanisms, measurement and clinical implications in humans.Gut. 2019;68(8):1516-1526. doi:10.1136/gutjnl-2019-318427
Sharma N, Bhatia S, Chunduri V, et al.Pathogenesis of celiac disease and other gluten related disorders in wheat and strategies for mitigating them.Front Nutr.2020;7:6. doi:10.3389/fnut.2020.00006
Armstrong LE.Rehydration during endurance exercise: challenges, research, options, methods.Nutrients.2021 Mar;13(3):887. doi:10.3390/nu13030887
Erdman KA, Jones KW, Madden RF, Gammack N, Parnell JA.Dietary patterns in runners with gastrointestinal disorders. Nutrients. 2021;13(2):448. doi:10.3390/nu13020448
Phillip NA, Ahmed N, Pitchumoni CS.Spectrum of drug-induced chronic diarrhea.J Clin Gastroenterol. 2017 Feb;51(2):111-117. doi:10.1097/MCG.0000000000000752
National Institute of Diabetes and Digestive and Kidney Diseases.Definition & facts for irritable bowel syndrome.
International Foundation for Gastrointestinal Disorders.IBS diet.
Kim JY, Lim MH.Psychological factors to predict chronic diarrhea and constipation in Korean high school students.Medicine (Baltimore).2021 Jul 9;100(27) e26442. doi:10.1097/MD.0000000000026442
Yang J, Fox M, Cong Y, Chu H, Zheng X, Long Y, Fried M, Dai N.Lactose intolerance in irritable bowel syndrome patients with diarrhoea: the roles of anxiety, activation of the innate mucosal immune system and visceral sensitivity.Aliment Pharmacol Ther. 2014;39(3):302-11. doi:10.1111/apt.12582
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