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Can You Actually Train Your Gut to Overcome Common GI Issues?

You may be able to stop nausea, runner’s trots, or cramps from sidelining your long runs or races.

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Although we’ll do anything to avoid them, gastrointestinal (GI) issues happen to almost every runner at some point. Meb Keflezighi stopped seven times to vomit or dry heave before completing 26.2 in the 2016 Olympics. Anywhere from 30 to 90 percent of distance runners have reported experiencing intestinal problems related to exercise.

Between runner’s trots, nausea, and stomach cramps, there’s a whole host of things that can go wrong in the gut during a run. The keys to minimizing GI issues is understanding what’s causing them and eliminating potential triggers.

We tapped two experts, Tamara Duker Freuman, M.S., R.D., a New York-based registered dietitian, and Patrick Wilson, Ph.D., R.D., associate professor of exercise science at Old Dominion University, to find out the most common GI complaints among runners and whether or not you can train your gut to overcome these problems.

Common GI Issues Among Runners

According to Wilson, runners deal with a “range of gut problems” including nausea and vomiting, reflux-type symptoms, fullness, bloating, cramping, side stitches, gas, the urge to poop, and loose stools.

Freuman adds that the most common GI issue she sees among runners is diarrhea or the sudden and urgent need to defecate. As many runners know, these not-so-fun side effects can interfere with training and races, from the minor need to take a break to the more severe decision to forfeit a race.

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What Causes These GI Issues?

Why is it that you can eat a huge pancake breakfast before going on a hike, but a small slice of toast prior to a run could leave you dry heaving or sprinting to the bathroom? Well, there are a few factors that are unique to running that cause GI distress.

“Intense physical activity, including running, tends to stimulate GI motility, which can lead to the increased need to move one’s bowels,” Freuman says.

Since blood is being redirected to working muscles during exercise, the gut may experience an 80-percent decrease in blood flow. This causes a decrease in overall gut function, which can cause nausea, reflux, intestinal cramping, and diarrhea. Not to mention that the sheer act of repetitively jostling the stomach up and down doesn’t exactly make your GI tract feel calm.

And, let’s not forget about the large role that nutrition plays in the GI system. You may unknowingly eat or drink something before a run that doesn’t sit well in your stomach. Some nutritional triggers for GI distress include:

1. High-fat foods: Fat takes longer to digest than carbs and protein. If you consume a fatty meal before or during exercise, that food will sit in your stomach during your run, causing nausea and vomiting, reflux, heartburn, or bloating.

2. Aggressive carb intake: For long-distance races, it’s common for runners to supplement with high-carb fuel such as sports drinks, gummies, or gels. “Certain sugars used in such products—like fructose, lactose, and sugar alcohols—can be poorly absorbed, and they often draw water into the bowel,” Freuman says. “This can result in osmotic diarrhea, particularly when coupled with more rapid GI transit times [the time it takes for your food to travel through your stomach, small intestine, and colon] from the run itself.”

3. Dehydration: Researchers have found that not getting enough fluids is linked to slower gastric emptying, meaning that food sits in the stomach longer and causes GI distress.

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Can You Train Your Gut to Overcome GI Issues?

Wilson says it’s possible to train your gut in certain situations.

“If an athlete’s gut issues typically occur when they ingest food or fluid during exercise, then they are potentially a good candidate for gut training,” he says. “However, if their gut issues affect them more generally or are due to non-nutritional causes—like stress or anxiety—then it’s questionable whether training the gut will be of value.”

To attempt to “train your gut” to overcome common nutritional problems, Wilson recommends consuming a relatively aggressive rate of carbohydrate or fluid during training sessions.

“For example, if an athlete normally consumes 30 grams per hour of carbs, during a gut training protocol they may bump that up to 60 grams per hour.”

Over time, Wilson says this will lead to the intestinal carbohydrate transporters to take in more carbs and decrease perceptions of fullness or discomfort.

“Some of these adaptations are nutrient-specific—eating more [carbohydrates] increases [carbohydrate] absorption—while others are more general, such as eating a larger volume of food accustoms someone to the feeling of being full while exercising.”

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Freuman, however, says training the gut may not be so simple.

“The intestines are composed of smooth (involuntary) muscles, not voluntary skeletal muscles that are under our control,” she says.

That said, she does suggest supplementing with a soluble fiber the evening before a morning run (or the morning of an evening run) to help slow GI transit time and ensure formed, cohesive stools.

“For mild cases [of runner’s trots] something like methylcellulose (Citrucel), wheat dextrin, or guar gum (Benefiber) ought to do the trick. For severe cases, I’d recommend calcium polycarbophil (Fibercon),” Freuman says.

If you aren’t quite sure what’s causing your GI issues (but you think it might be a nutrition issue), consult sports dietitian. But if the issues are severe, ask your doctor for a referral to see a gastroenterologist.

Whether your gut-training is successful or not, you should be practicing your fueling strategies during your training to best prepare your body and gut for race-day. And since racing may be on pause right now, it’s a great time to experiment with different prerun and on-the-run fuel to really dial in your nutrition once racing resumes.

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