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How to poop before running?

Feb 07, 2024

Every runner dreads the pre-run toilet no-show. The fear of a nature call mid-jog can lead to some unwanted sprinting. Trust me, I've dashed in ways I hadn't planned on... That's exactly why I've created this guide: to help you understand your gut's behaviour during a run, identify what raises the risk of mid-run pooping, and offer strategies to ensure you start your run light, without the... extra baggage that hinders fun and performance.

What's happening inside your gut?

Exercise-induced gastrointestinal symptoms (EGIS) are a common nemesis, affecting 27% of marathoners and a staggering 60-96% in ultra-marathons. Behind this is a condition known as "exercise-induced gastrointestinal syndrome," where normal exercise responses throw a wrench in gastrointestinal integrity and function. During exercise, blood flow shies away from the gut to favour muscles and skin, stress hormones surge, and the physical jolting can all contribute to a gut function detour. If combined with a bowel not fully emptied before the run, the race against time may turn into a literal race to the nearest toilet. Common lower gut symptoms among runners include abdominal cramps, flatulence, the urge to defecate, diarrhea, and even bleeding. These symptoms can persist for hours post-run, unfortunately. Thus, ensuring your gut is empty before heading out is a tactical move. But how exactly do we make that happen?

How can I ensure a pre-run poop?

Initiating a bowel movement is highly personal, but there are several strategies that often help. By practicing various nutritional and hydration strategies and observing their effects, you'll start to unravel the mystery of your gut behavior and be able to manage it with confidence when it matters most.

Check your fibre intake: Fibre is essential for health and promotes regular bowel movements. However, overdoing it before a run can leave significant residue in your bowels, which might decide to 'make a break for it' once you start running. Cutting back on fibre 24 hours before your run can reduce this risk. Yet, this isn't a tactic for regular training days, as fibre is vital for gut health and chronic disease prevention. In fact, for some runners not consuming enough fibre may be the reason for being unable to poop before running. Balance is key.

Manage your morning routine: Typically, people experience bowel movements in the first two hours after waking. Yet many runners are out the door within 15 minutes of rising. Allowing more time between eating, hydrating, and running can ensure your gut does its job before your feet hit the pavement. During busy days, planning a route with accessible toilets may be a practical solution.

Carbohydrates and hydration: Eating and drinking pre-run can trigger the gastrocolic reflex, signaling your colon to clear out. Adequate hydration day-to-day and before running is also critical. It softens stool, making it easier to pass. Monitor your urine colour, thirst, and daily weight fluctuations to gauge hydration levels.

The power of coffee: Coffee's buzz is loved by many, not just for the caffeine kick but also for its bowel-stimulating effects. Coffee spurs colon muscle activity and increases pressure in the anus, which prompts the urge to poop. The acids in coffee can also increase levels of the hormone gastrin, which stimulates involuntary muscle contractions in your stomach to get your bowels moving. So decaf coffee may also have a laxative effect. For some, caffeine may trigger a bowel motion that is much desired prior to running, however for others this effect may unfortunately persist throughout running also. For those with lactose intolerance, skipping milk could prevent mid-run issues. It's worth experimenting to see how coffee affects you personally.

A gentle warm-up: The jostling nature of running is thought to be a factor in speeding up gut transit time and leading to bowel motions during exercise. Take advantage of this by going for a short walk or jog prior to racing or the key part of your training session. Often this moves bowel contents along so you are comfortable for the part of your run that matters.

And if nature doesn't call?

While some runners turn to anti-diarrhoeal medications like loperamide, found in brands such as Imodium and Gastrostop, as a preventive measure, it's important to note that their effectiveness for staving off exercise-induced diarrhoea lacks substantial clinical evidence. Moreover, loperamide isn't without its downsides; potential side effects range from abdominal cramps, constipation, and flatulence to more severe reactions like allergies or heart issues. Consequently, its use should be approached with caution. As a practical measure, plotting your run along a path with available restrooms can offer reassurance. Additionally, for those with a history of mid-run emergencies, packing emergency toilet paper, hand sanitising wipes, and zip lock bags can provide a level of preparedness for any unforeseen stops in nature.


Mastering the art of pre-run digestion is crucial for uninterrupted runs and optimal performance. It involves a personalised approach to understanding your body's signals, pinpointing specific triggers, and creating a tailored plan for nutrition and hydration. With the expertise of an Accredited Sports Dietitian, you can align your digestive processes with your running goals. I'm committed to guiding you towards that triumphant pre-run bowel movement, ensuring a smooth run where the only sprints are in your stride, not toward a restroom. Let's work together to secure that pre-run comfort and keep you focused on the finish line!

Download my ebook on carbohydrates to fuel for a PB here!


Costa et al 2017, 'Systematic review: exercise-induced gastrointestinal syndrome - implications for health and intestinal disease', Alimentary Pharmacology and Therapeutics, DOI: 10.1111/apt.14157.

Lis D 2018, 'From Coeliac disease, gluten sensitivity vs gluten sensationalism, to FODMAP reduction as a tool to manage gastrointestinal symptoms in athletes', Sports Science Exchange, vol. 29, no. 189, pp. 1-6.

NHS 2021, Loperamide,

Wilson P 2020, 'The Athlete's Gut', Velo Press, USA.

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