Yes, exercise can seriously affect your bowel movements - and this is why.

Image via iStock

We know exercise increases your muscle and fitness levels, but have you ever found your bowel movements a little more energetic than usual after your run, too?

Well, there’s a reason for that: it turns out your toilet habits are significantly effected by how active you are.

In a 2011 study published in the Scandinavian Journal of GastroenterologySwedish researchers looked into the ‘gastrointestinal characteristics’ (read: poo movements) of a group of 15 elite athletes during a week of intense training, compared to a week of rest.

During the heavy training week, they found participants had a higher number of bowel movements, increasing from 1.3 during rest week to 1.5 a day when they were training.

Using the Bristol Stool Form Scale, a measure of poo consistency from one to seven — seven being the most watery — the athletes also recorded looser stools, with an average rating of 4.2 compared to 3.9 during the rest week.

While there is no doubt exercise affects your bowels, exactly how it does depends on the degree of exertion and type of exercise you do. (Post continues after gallery.)


“Strenuous exercise may provoke heartburn and diarrhoea, likely caused by increased intestinal motility (contractions) and changes in hormones and neurotransmitters during exercise,” says gastroenterologist Dr John Halliday.

Issues with bowel movements are particularly common among runners, which some partly attribute to the effect the repetitive movement of feet pounding the ground has on a runner’s intestines.

A 2011 study published in the Journal of the International Society of Sports Nutrition also links the problem with changes in blood flow. When you exercise, your body diverts blood flow away from your internal organs and towards the muscles you’re using to exercise instead.

There's a lot going on in your body when you run. Image via iStock.

A lack of fluids also contributes. When you're dehydrated, it's hard for your intestines to actually absorb anything, so the only option for it to do is to simply get rid of it from the body.

So should we be working out around, well, our bowels?

While your bowel movements do not directly determine the best time to exercise, Dr Halliday says they can guide your routine. "Obviously if you typically open your bowels in the morning, it might be best to wait until after toileting before going for a long run in the middle of nowhere," he says. (Post continues after video.)

On the flipside, a lack of frequent activity can contribute to some serious bowel issues.

"Exercise has been demonstrated to have benefits that include a reduced risk of colon cancer, constipation and other diseases of the GI tract, including gallstones," Dr Halliday says.

This is because being sedentary can often slow the digestive system, making stools harder, less frequent and difficult to pass. This is why doctors will typically recommend boosting your exercise routine if you suffer from constipation.

Even if you are already active, if you amp up your fitness regimen you will notice your digestive system responding — and that's not necessarily a bad thing. Just make sure there are toilets nearby!

Over to you — have you ever noticed your toilet habits change with exercise?

00:00 / ???