Fitness and triathlon editor, Adam Kelly, gets to the bottom of why running makes you poo.

First up, you are not alone. The fact is that shit happens and happens to most of us who jog or run for extended periods. Indeed according to a review of gastrointestinal problems in distance running published in the International SportsMed Journal, 37 to 71% of runners experience similar issues.

And rest assured it happens to the best too. I happened to be lucky enough to be cycling along beside Paula Radcliffe in the Beijing Olympic Marathon. In the closing stages of the race, she suddenly disappeared, only to reappear and resume running.

The same thing happened to me for the first time while racing the National Triathlon Championships. A quick stop is so worth it, so you can refocus on your running.

The fact that you are about to race stimulates the ‘fight or flight’ response in your body, causing you to empty your bowels.

There is also a reason, why before any large sporting event, such as a triathlon, that the start area is riddled with port-a-loos. The fact that you are about to race stimulates the ‘fight or flight’ response in your body, causing you to empty your bowels. The body is very clever really – as it’s best to respond proactively – rather than reactively half way through the race!

If there is food in there, the body wants to get rid of it, as quickly as possible.

Your stomach and intestine are actually held in suspension, and while empty are perfectly balanced. The structure of the suspension is made up of little ligaments which attach the stomach to the body. When we ingest food or liquids, we can upset the balance of the stomach, causing stitches due to spasm. Naturally or primitively, we are designed to eat and drink while at rest, then take a snooze, before setting off to go hunting or gathering food again. So if there is food in there, the body wants to get rid of it, as quickly as possible. Here in lies the poop problem.

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 Here are some dos and don’ts to try and help you control your problem, both on normal training runs and on race day. 


  • Try and run first thing in the morning – before breakfast and after using the loo. Your food should be digested fully over night and is ready to be disposed of. A hot drink might spur you on.
  • Develop a regular morning time toilet routine.
  • Movement often stimulates bowel movement so for training runs, line up a usable loo, in the early stages of your run route, or simply re-run past your own front door.
  • Bring toilet paper out with you – the little packs of tissues work a treat.
  • If you are running in the evenings, only eat foods that you know agree with you before your run. And eat lighter foods during the day which are low in fibre.
  • Eat a consistently good diet so that you build up good gut health over time.
  • If you have very regular problems you can take a diarrhoea medication for events but you are only covering up the original problem. It might be better in the days leading to an event to reduce substantially the amount of fibre in your diet.
  • If you are doing an event where you will be handed snacks and drinks, they will often be sponsored. Find out who the sponsor is, and then test the products yourself in your training so that you know that they will agree with you.


  • Don’t eat foods that are known to irritate the bowel. Spicy or curried foods can cause irritation.
  • Don’t eat high-fibre foods on run day. Watch out for the sweetcorn, which always seems to make an unwelcome appearance.
  • Don’t ‘drink n run’. Alcohol irritates the bowel, especially when drunk on an empty stomach.
  • Don’t eat within three hours of running.
  • Don’t go to the expense of getting food allergy tests. Instead, listen to your body, and observe your stomach and bowel behaviour in the short and medium term after eating.

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