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Why Does Running Make You Poop (And What To Do To Prevent It)

You’re not alone if you’ve been hit by the urge to poop when running. I once stopped and used a spectator’s bathroom when running my first marathon.

It’s embarrassing but right up there as one of the top concerns for all runners. So why does running make you poop and how do you stop pooping while running.

why does running make you poop

Why Does Running Make You Poop?

I’ve been doing my research on this one. Suffering from gastrointestinal (GI) complaints when running is commonplace. Especially in races. It doesn’t matter if you’re a complete beginner or an elite athlete, pooping is a problem.

Just look up Paula Radcliffe, until recently the fastest women’s marathon runner of all time. A true legend of a runner. How is she remembered by the British tabloids? For that poop in the London Marathon in 2005.

So we’re all agreed it’s pretty embarrassing, especially if you’re taken short in a race. But why does it happen in the first place?

The up-and-down motion stimulates the colon

This seems to be the main reason. All that bouncing up and down as you run will make your colon work effectively. Your colon is just doing its job. It has no idea it’s picked the worst possible time to make you feel you need to go.

Sugary energy gels or sports drinks

The theory is sugar prompts you to release more water into the GI tract. This loosens your stools – just what you don’t want in the middle of a run.

Most energy gels are packed full of highly processed ingredients which may not sit too well in your stomach. As an alternative, try experimenting with more natural energy gels or energy alternatives. A favorite of mine is Medjool dates but the high fiber will affect some people.

Being active and drinking more water

A great cure for constipation is being more active and drinking more water. Just what you do when you go running!

Running diverts blood away from GI tract

Start running and your body will divert blood away from the GI tract to where it’s needed – the body parts working the hardest. This can cause problems; abdominal pain, diarrhea, and the need to find a bathroom!


Dehydration can also be a cause of GI distress. It can become a vicious cycle. You need to drink to rehydrate but your body is unable to keep down the fluids. Diarrhea can be part of this distress.

It’s a huge problem for ultra runners. When you’re running for hours at a time, it can be difficult to avoid dehydration. I know from bitter experience how this cycle can destroy your performance.

Race day anxiety

Anxiety can trigger a reaction in your gut. The gut is controlled by the central nervous system in your brain so it’s not surprising anxiety can cause GI distress. It’s yet another reason why running makes you poop!

How To Avoid Pooping While Running

Getting this right will take a little trial and error. Everyone’s different. What works for one runner may not work for another. That said here are my top suggestions:

Schedule runs until after you’ve moved your bowels

Now I know this is easier said than done. Sometimes you don’t have much time to fit in a run and a lot of runners head out first thing in the morning.

If you have an important race coming up, with an early start, try getting up early in the days leading up to the race. Train your bowel movements ready for race day!

On race days, a warm-up jog and toilet stop before the race starts may do the trick.

Eat one to two hours before you run

Running on a full stomach is asking for trouble. Try and avoid eating an hour or two before your race.

This can be difficult with a long race such as a marathon where you want to keep your energy levels topped up. I suggest experimenting during training to find out what works for you.

Avoid trigger foods

Trigger foods that affect your GI tract will vary from person to person. I suggest you experiment. Add food and bathroom columns to your training log to see if certain foods cause issues.

Common triggers are:

  • Sweeteners (these can be natural or artificial)
  • Fat
  • Grains
  • Dairy
  • Legumes
  • Anti-inflammatory medicine (such as ibuprofen)
  • Caffeine

It will take time and patience to work your way through all these triggers. Using your training log you may get some insights into which foods to avoid before races.

Stay properly hydrated

Keeping hydrated both before and during your run will be one the best ways you can avoid GI tract problems. When you’re running in hot weather, hydrating properly the day before is really important.

Eating during a run, experiment with what works

For longer runs, refueling is essential but getting the balance right is important. You often see new runners at marathons loaded down with energy gels. These energy-fueling gels can often be the source of GI tract problems.

Test out different gels and find a balance for refueling when you need it. Some gels are less sweet than others. or contain only natural ingredients and can be easier to digest on the run.

For ultra races where you’re wearing a race vest, there’s scope to take real food for refueling. Experiment, log your reactions, and discover what works.

So Why Does Running Make You Poop?

In conclusion, there are lots of reasons. Finding your trigger foods leading up to a race, experimenting with different gels, and avoiding excessive pre-race carbo-loading will hopefully help to ease the problem.

If all else fails I know some runners resort to popping an Imodium capsule before a big race. Like all things race-related, make sure you test this fix out on a training run first. It’s definitely a last resort.

It’s not harmful to continue running when you feel the urge to poop. It’s just uncomfortable and there’s the chance of an embarrassing incident.

If the worse happens, most big race organizers now provide toilets along the route and if you’re running on the trails there’s always a bush or boulder to hide behind!

why running makes you poop
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