Gastrointestinal (GI) problems are very common in endurance athletes and is often referred to as exercise-induced GI distress.

It’s a horrible situation to be in, and unfortunately, most athletes have experienced exercise-induced GI distress a time or two.

Just ask athletes. We almost all have a horror story of planning training routes with bathrooms available, running with toilet paper, diving into the ditch to relieve yourself before you soil your shorts, and even situations of athletes failing to complete a race due to GI problems.

Factors That Can Influence Exercise-Induced GI Distress

There’s actually quite a bit of research on GI issues in runners and endurance athletes. I have sports nutrition textbooks with entire chapters on GI issues.

The problem is that there is no clear sign as to the direct cause because symptoms are highly individual to the person and there are usually no clear patterns.

Common GI symptoms include heartburn, stomach pains, cramping, bloating, diarrhea, reflux, nausea and vomiting and they can vary in severity, but all symptoms can impact an athlete’s performance.

What can contribute to GI problems:

• Nerves, stress, anxiety, and pre-event jitters can play a role in causing an upset stomach or diarrhea.

• Exercise accelerates intestinal transit time. For people who have trouble with constipation issues, dietitians often recommend exercising to help “move things along.” For people who have normal bowel movements, exercise may cause movements to happen to quickly.

• Physiologically speaking, especially in running-type sports GI problems can occur due to jostling of the intestines and/or reduced blood flow to the intestines as blood is being diverted to muscles.

• Nutritionally speaking, certain foods don’t sit well in an athlete’s stomach or take a long time to digest. Foods high in fiber, fat, protein and concentrated carbohydrates solutions may play a factor. Dehydration may also contribute to the problem.

Looking for more runner’s nutrition content? Check out my latest blog post on do runners need more calories!

How can you prevent GI issues as a runner?

Here are a few easy ways you can help to prevent exercise-induced GI distress:

• Drink extra water to prevent dehydration. Use electrolyte + hydration mixes as needed. I like LMNT.
• Limit caffeine. Caffeine is known for having a laxative effect, especially coffee. There’s something about coffee and needing to poop soon afterwards. 
• Avoid high-fiber foods for a few days before your competition. Fiber increases fecal bulk and movement. Eating a fiber-rich diet during training is great to keep your bowel movements regular, but for competition day you will want to decrease your need to travel to the bathroom.
• Limit foods that contain sugar alcohols such as sorbitol, mannitol, xylitol, etc. Sugar alcohols don’t fully digest and can ferment (a.k.a. – cause gas) in the gut.
• If you have an inkling that you may have a sensitivity to gluten or Celiac disease, consult your doctor for testing. Most people with these diagnoses will see a rapid response, showing improvement within weeks when eliminating gluten from their diet.
• As there are many factors that can contribute to GI problems, it’s important to trial different eating and drinking patterns and types of foods. Creating a list of “safe” foods to eat and a pre-competition ritual will provide you with the confidence to know you won’t lose your race due to an unexpected trip to the porta-toilet.
• For a lot of athletes, bowel issues may resolve themselves as training progresses so this hopefully will be the case for you.
• You may want to consult a doctor. There could be a potential bowel disease or problem that requires medical action.

Nutrition Tips for Triathlons

Personally, this is my go-to solution for triathlons:
1) Eat a low-fiber diet for at least three days prior to the event. Limit whole grains. No fibrous veggies. No beans/legumes.
2) On the evening prior to the event, I got for an easy-paced run for 20-30 minutes. I’ve affectionately dubbed this as my “colon-cleanse run” and it works every time to take care of the bowel business and not have to worry about it during the race.

The Takeaway

As I’ve mentioned, this issue is SUPER common in endurance athletes. So you are not alone.

If things are really bad. Consult a doctor, make sure there isn’t a medical issue, and then consult a dietitian, we’ve got ways to help you work through this.

My number one priority for my clients is to enjoy their race without worrying about porta emergencies and feeling their very best.