New Research Shows Anxiety Contributes to Athletes’ GI Distress

Along with swimming, biking, and running, there’s a commonly thought of fourth discipline in triathlon: eating. This is for good reason, especially in long course events, where the ability to take in enough calories is vital to sustaining the physical effort required to complete the race.

After about an hour of exercising, our bodies have depleted our limited stores of carbohydrate. While we can switch to using fats and proteins, these fuels are significantly less efficient and necessitate a drastic reduction in effort unless we are able to also take in the preferred fuel of our muscles, carbohydrates, in the form of nutrition during the workout or race.

Like the physical legs of triathlon, your nutrition must be practiced and planned in order to be done well. And even with practice, many a triathlete can relate detailed stories of how they suffered all manner of stomach troubles on race day, resulting in an inability to fuel and a disastrous finish.

Over the years a fair amount of research has been dedicated to understanding what factors contribute to an athlete’s ability to properly fuel during an event. This has enabled us to better give the best advice for eating and drinking on race day.

How Anxiety Contributes to GI Problems

High concentrations of carbohydrates and salt, and protein and fat content, combined with prolonged efforts at high intensity contribute to delaying gastric emptying. That, in turn, can lead to stomach fullness, nausea, and vomiting. Competing in warm environments exacerbates this problem by diverting blood flow away from the gut to the skin and can lead to fluid leakage into the intestines. This adds to the problem of not being able to get fluids or nutrients in with an actual loss of fluids at the same time.

Yet, even before that all goes into effect many athletes struggling with nausea or vomiting even at the start or before a race, which is simply exacerbated as the day goes on. Why?

Dr. Patrick Wilson, PhD, directs the Human Performance Lab at Old Dominion University and is the author of The Athlete’s Gut: The Inside Science of Digestion, Nutrition and Stomach Distress. Dr. Wilson believes that for many athletes there is an additional contributor to gastrointestinal issues on race day: their mental state. “Despite my own experiences with being unable to eat because of nervousness on game days, when I started to do research on gastrointestinal distress in athletes I was surprised to find that there was very little data out there on this subject,” he said. “And this was even though I had heard the same experience from many other athletes, especially endurance athletes anecdotally for many years.”

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Through his own research, Wilson has demonstrated that, indeed, stress and anxiety levels can have a role in gastrointestinal distress so many of us experience in the form of nausea, vomiting, diarrhea, and abdominal pain. “The gut and gut activity is very much influenced by the sympathetic and parasympathetic branches of the autonomic nervous system,” he said, “and in addition to that there is a whole network of nerves within the walls of the gastrointestinal tract that some refer to as a ‘second brain.’ Under conditions of anxiety or mental stress, these systems can have important effects on the gut, causing changes in motility and resulting in significant symptoms for people.”

Beyond just the connections to the brain, there are also hormonal responses to anxiety that play a role. “Under conditions of stress the brain secretes corticotropin releasing hormone (CRH) that stimulates a release of cortisol from the adrenal glands. Cortisol activates the sympathetic nervous system and causes decreases in activity in the upper gastrointestinal tract, while conversely increasing activity in the lower part of the tract,” Wilson explained. What this means for an athlete is that under conditions of stress, when CRH is released, it can directly contribute to stomach fullness, reflux, and vomiting, and at the same time lower abdominal cramping and diarrhea.

Wilson’s research has shown that both the background level of a person’s anxiety, as well as the increased anxiety on the morning of an event correlate with certain gastrointestinal symptoms, particularly reflux, nausea, and cramping. These effects often persist throughout the duration of an event. That means how stressed you are in the days and weeks before has an affect, as does the specific anxiety or race-day nerves you experience going into the event.

What You Can Do About It

Although this research does in fact suggest a correlation between stress level and gastrointestinal symptoms, Wilson is quick to admit that this is not an issue for all athletes. “Based on the size of correlation that we have observed in our research, there is rarely one thing that causes the issue for these athletes because gastrointestinal upset is truly multifactorial,” he said. “But, for a subset of athletes, those who have the highest levels of anxiety, that’s where you are really going to see this come in to play.” He estimates this number might be as high as one-third of athletes—making it something that’s clearly important to consider if you experience ongoing gastrointestinal issues.

As for managing it, no good research has been done yet, though Wilson’s lab is working on prospective trials that will evaluate different therapeutic options. For now, he advises those athletes who do experience high levels of anxiety and associated stomach issues to try various proven stress reducing strategies. Even though these may not yet have been shown to help with the gastrointestinal symptoms, they have been shown to be helpful with reducing anxiety and have no downside.

“If you’re an athlete who has race day jitters and nervousness that you think may be contributing to your stomach problems, then trying some low risk interventions is a great idea. That can be relaxing music, deep breathing exercises, or even meditative efforts. All of these might be helpful and are certainly worth a try.”

Given the fact that anxiety seems to play a role in gastrointestinal problems for many athletes, it’s not surprising that those athletes with a history of this problem also experience heightened anxiety on race days because of the fear of experiencing stomach problems. This type of feedback loop can be very destructive and cause those athletes a lot of emotional distress. So while the relaxation techniques that Dr. Wilson suggests may not yet be proven to alleviate the gastrointestinal troubles provoked by stress, we do know that they are helpful in reducing anxiety in general. Given the low risk and potentially significant reward, if you are one of the people so affected, it’s a great place to start on that fourth (and fifth) discipline.

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