If you’re a runner it’s not uncommon that at some stage mid-stride you have experienced that literally bowel wrenching feeling of urgency to find the ‘facilities’ in a hurry! Approximately 30-50% of distance runners have had exercise-related intestinal problems (de Olivera 2011). If you are part of the fairer sex, unfortunately you are more likely to experience such issues. (Clarke 2010). Although there is no magic bullet for preventing tummy troubles during running, there are quite a few things you can consider to reduce your risk of the trots.

What causes “runners’ trots”?

The answer to this is different for different people, sometimes there may be multiple causes, and at other times the exact cause is unfathomable.

Common factors that may contribute to runners’ trots include:

  • Exercise-related hormones released (into the gut) during running,
  • Mechanical jostling of the intestines,
  • Diet,
  • Fuels chosen during running,
  • Poor hydration practises,
  • Physical stress of running and/or lack of adaptation (not well trained),
  • Anxiety and stress prior to running,
  • Some medications,
  • Lessened blood-flow to the gut,
  • (Pre-existing) clinical conditions such as IBS, Coeliac Disease and Lactose intolerance.

Exercise-related hormones

Hormonal changes during exercise include elevation in levels of gastrin, motilin, somatostatin, glucagon, pancreatic polypeptide, and vasoactive intestinal polypeptide (Swain 1994). They all affect the gut to some extent. Predominantly there is a speed up in transit time through the gut, which even occurs with other non-running exercises such as resistance training.

Mechanical jostling of the intestines

Our intestines are not set in concrete, in fact, if you can imagine them suspended on stretchy sheets within your abdominal cavity, bouncing up and down with the impact as we hit the ground during running. This sends our intestines sloshing around and bumping into the solid walls of our abdomen. Mechanical stress can cause micro-bleeds in our intestines, which contribute to intestinal injury.


Dietary factors which may come into play to increase risk of exercise induced diarrhoea include; fibre intake (up to 3 days before), coffee, tea, warm beverage and caffeine intake, fatty foods, spicy foods, alcohol (in significant quantities), sorbitol (in sugar free gums and sweets), high dose vitamin C supplements (Clarke 2012). If any of these is suspected as a factor for you it is a good idea to keep a detailed food diary, especially if considering exclusions. Consulting an Acc Sports Dietitian would also be a worthwhile venture.

Fuels chosen during running

Sports foods and beverages fuelling your running training and racing come in many different forms these days; gels, beverages, chews and bars. Concentration and types of carbohydrates in these fuels should be considered in cases of ‘runners’ trots’. High concentration of carbohydrate, especially in an “untrained” gut increases osmotic load and can cause ‘water’ to be pulled into the intestines to dilute. Cramping and/or diarrhoea may result.

Poor Hydration Practises

Runners who lose more than 4% of their body weight in sweat are more likely to experience faecal urgency, especially towards the ‘back-end’ of an exercise session. Looking at hydration practises around and during running sessions could be key, not only to preventing diarrhoea, but to improving performance and recovery. Talking to an Acc Sports Dietitian about your hydration needs is a great step.

Physical stress of running/ poor training adaptation

The physical stress on the gut of running can cause a type of inflammation of the colon called Runners’ Colitis. It is usually a temporary condition, brought on by long mileage or the intensity of a run. Runners’ Colitis can see you running to the toilet more frequently. If you are a novice runner and less well adapted to the stresses of running/ taking fuel during exercise this often contributes to the problem.

Anxiety and stress prior to running

Most people who participate in running events would be all too familiar with the long pre-race porta-loo queue. The butterflies in your belly prior to the gun going off offer you a significant physiologic advantage in terms of running performance, elevating the heart rate and preparing you for ‘flight’. The stress hormones involved in this ‘fight or flight’ response may have effects on the smooth muscles of the gastrointestinal tract making diarrhoea more likely.

Lessened blood-flow to the gut

During exercises such as running there is a redistribution of blood-flow to the working muscles, which results in ‘hypoperfusion’ of the gut (lessened blood flow to the gut). This can have a couple of results; more unabsorbed sugars and foods in the gut, greater intestinal permeability and injury, and gut dysfunction (van Wijck 2011). The symptoms of this can be anywhere from mild to potentially life threatening, such as blood loss in faeces for hours after endurance events (Jeukendrup 2005).


There is a long list of medications, which can contribute to diarrhoea from magnesium containing antacids, to antibiotics and some oral hypoglycaemic agents used for treating diabetes. It is recommended that if you are experiencing runners’ trots, and taking medications, these are reviewed by your GP.

Clinical conditions

Intolerances, Coeliac Disease, Irritable Bowel Syndrome and Inflammatory Bowel Disease can all be causes of diarrhoea in their own right, especially if undiagnosed. If the other above factors have been considered it is important to visit your GP in order to rule out possible clinical conditions. Working with an Accredited Practising Dietitian to achieve dietary modifications around such conditions would also be useful.

If your usual trot has become more like a race for the toilet considering the above factors, and consulting your GP and/or Accredited Sports Dietitian where necessary may allow you to focus more on your performance than on the porcelain hunt!


  • Clarke N. Recognising and Managing Exercise Associated Diarrhoea. ACSM’s Health and Fitness Journal 2012; 16(3): 22-26.
  • de Oliveira EP, Burini RC. The impact of physical exercise on the gastrointestinal tract. Curr Opin Clin Nutr Metab Care. 2009; 12 (5): 533–8.
  • de Oliveira, E.P. & Burini, R.C. J Int Soc Sports Nutr (2011) 8: 12. doi:10.1186/1550-2783-8-12
  • Jeukendrup AE, Jentjens RL, Moseley L: Nutritional considerations in triathlon. Sports Med. 2005, 35: 163-181.
  • Swain R. Exercise-induced diarrhoea: when to wonder. Med Sci. Sports Exercise 1994; 26(5): 523-526.
  • van Wijck K, Lenaerts K, van Loon LJC, Peters WHM, Buurman WA, Dejong CHC (2011) Exercise-Induced Splanchnic Hypoperfusion Results in Gut Dysfunction in Healthy Men. PLoS ONE 6(7): e22366. doi:10.1371/journal.pone.0022366