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The Gastrointestinal Effect of Running on Bowel Movements

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  • Post last modified:September 26, 2023

I’ve defecated in my pants while jogging. There, I’ve uttered it. I was approximately a mile away from completing my 6-mile circuit when the abdominal agony arose. As a seasoned runner, I presumed the discomfort was standard abdominal cramps, and I was quite determined to conclude my workout, so instead of halting, I simply persisted with my journey. Then, out of nowhere, it began to occur, appearing to be beyond my control. Needless to say, it was a rather distressing experience.

To decrease the likelihood of encountering a situation like mine (and to prevent any further unforeseen surprises), we have gathered information on why this phenomenon happens and how to minimize the chances of experiencing a mid-run bowel movement.

Gastrointestinal Problems for Runners: A Widespread Issue

Fortunately for my dignity, my tale is quite common. Runners of all types, ranging from ultramarathoners to casual joggers like myself, encounter similar digestive problems. “In certain studies, up to 80 percent of runners have reported gastrointestinal disturbances, including abdominal pain and bowel irregularities,” states gastroenterologist James Lee, M.D., of St. Joseph’s Hospital in Orange, California. (While we’re addressing this, here’s the appropriate way to defecate — and indeed, there is an appropriate way.)

To compound the issue, a scientific review from 2019 concluded that younger athletes and those engaging in longer-distance and longer-duration activities tend to experience heightened gastrointestinal (GI) symptoms.

Why Does Running Stimulate Bowel Movement?

Multiple factors contribute to the urge to defecate while running, which span from gastrointestinal motility to genetics. For instance, in a study involving 221 male and female endurance athletes, a significant number of participants exhibited symptoms that were directly linked to a documented history of GI complications.

However, this does not imply that individuals devoid of GI problems are immune to encountering similar issues. As an example, colonic motility — signifying the frequency and consistency of bowel movements — increases during running due to the release of hormones in the stomach lining caused by the excessive bouncing while pounding the pavement, states Lee. The combination of all these factors is what can result in a mid-run bowel movement. He further mentioned that running (or any other form of exercise that causes your stomach to jostle) can also affect something known as mucosal permeability, which regulates the passage of substances from the GI tract to the rest of the body. This leads to a loosening of the stool, and suddenly, you find yourself realizing, “Goodness gracious, I urgently need to defecate!

In addition, when jogging, blood circulation increases to the muscles to assist in oxygenation and maintain body temperature, states Christopher P. Hogrefe, M.D., an adjunct associate professor of orthopedic surgery at Northwestern University Feinberg School of Medicine. “However, what individuals are unaware of is that it can reduce blood flow to the intestines, resulting in abdominal cramping and potentially the need to defecate,” explains Hogrefe.

How to Prevent Interruptions in Your Run Due to Defecation

While many of the factors that cause defecation during a run are beyond our control, there are a few things athletes can do to decrease the likelihood. Keep the following recommendations in mind when preparing for your next run.

Restrict certain food items.

Fiber, fat, protein, and fructose have all been linked to gastrointestinal issues while running, and dehydration appears to worsen the problem, according to a 2021 report in the journal Nutrients. Lee advises avoiding high-fat and high-calorie meals within three hours of running.

Refrain from taking aspirin and other NSAIDs like ibuprofen.

These types of medications have been found to increase intestinal permeability, leading to the gastrointestinal problems you are trying to avoid, as stated in a case study that examined endurance runners.

Time your meals appropriately.

Utilizing gastrocolic reflux to your advantage is crucial. The concept behind this intimidating scientific term is simple: After eating, your body seeks to make space for more food, resulting in increased movement in your intestines, explains Hogrefe. To leverage this, consume your meal at least two to three hours before your run to allow ample time for using the restroom and ensure a clear digestive system. Eating immediately before a run may be the cause of your digestive discomfort.

Begin with a gentle warm-up jog.

If running without needing a restroom break feels nearly impossible, Hogrefe suggests starting with a warm-up jog in your neighborhood so you can make a pit stop at home before proceeding with your actual run.

Of course, runners encounter various unique “complications,” and defecation is just one of them. Sometimes, it simply cannot be avoided — you can hope and pray that a restroom is nearby! If you find yourself in an unfortunate situation similar to mine, do not feel ashamed. Instead, congratulate yourself and welcome yourself to the club.

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