Exercise-Induced Gastrointestinal Distress: A Washington DC Horror Story

It was 90 degrees in the public restroom in front of the Washington Monument, and my stall had no lock. For unknown reasons the lock had been ripped off, and frankly the door could’ve fallen off its hinges at any moment. I had one running shoe clad foot pressed against the frame to prevent a tourist from walking in on me, while I stifled my groans as I attempted to stay conscious during the worst bout of exercise-induced gastrointestinal distress of my life.

Rural runners and trail runners have it easy, you’re out in the country, or in the mountains, and if GI distress hits it’s not fun but you can at least dash behind a tree or something. When I’m on a run on the National Mall in the middle of the summer, about to shit myself, my options are somewhat more limited. Not only is every tourist holding a camera, but in a city where everyone knows everyone, the last thing you want is to earn a reputation as the Monument Pooper. Congressional resolutions have been introduced and passed over less.

So there I was, in the Washington Monument restroom. At the first sign of impending disaster I had lurched towards the small structure, part-restroom part-information center, and fought for my life. Love in the Time of Cholera uncomfortably clear in my mind, and sweat pouring from my body in the sauna like tiled bathroom, it was by far one of the lowest moments of my time as a runner.

So why did this happen to me? Why would something like this happen to anyone? Why do people shit themselves during marathons, and why would anyone keep doing a sport that makes that happen?

I can’t answer the last question, but for the first three it all comes back to exercise-induced gastrointestinal distress syndrome. Sometimes referred to as EX-GIS, or amongst athletes simply as simply “GI”/”GI issues”/”Gastro”, EX-GIS is a complex and not yet fully understood phenomenon involving sudden and rapid gastric emptying during strenuous exercise. It is very common, and timing or conditions for onset can vary amongst individuals, making it difficult to provide guidance on prevention, but there are some key factors which can make it easier to avoid.

While some of the exact mechanisms of EX-GIS are still under investigation, there does appear to be both a scientific and anecdotal link between blood flow restriction and EX-GIS. As we exercise, blood is directed away from certain regions of the body in order to meet oxygen demand in working muscles. One such area is the splanchnic region (the guts), which is a very compliant area capable of holding a large volume of blood. Since there is a limited amount of blood in the human body, as portions of total blood volume are re-directed to flow through working muscles there is less blood available to continue autonomic nervous system processes, such as digestion. As a result, digestion, a highly complex enzymatic process, is affected in a way that results in the faster removal of waste, likely due to impaired nutrient absorption.

This issue of blood flow and availability is made worse by heat, which many athletes report as being a trigger for EX-GIS. As stated earlier, the splanchnic region is very compliant and capable of holding a lot of blood, but same is true for the skin. In order to cool the body, blood is directed away from the core and remains in the skin, and will typically do so until the brain has decided that it is sufficiently safe from heat stress.

Now, if you’re working hard, and a lot of blood has left the guts to go to your arms and legs, AND its hot outside, so a lot of blood has been re-directed into the skin, it stands to reason that you may be more susceptible to EX-GIS. It has also been noted by some researchers that a threshold of 60% of VO2max or higher may be the onset point for EX-GIS, which given the all the factors above, is not a very high threshold.

So how do we get a handle EX-GIS? In some cases you don’t, these things happen, and you take the hit and carry on with your life, and I personally hope you had a less humiliating experience than I did.

In most other cases, determining pre-activity fueling triggers can be crucial. Some people can eat spicy food and then tear off on a 10 mile run, but I have learned, painfully, that I can’t eat anything more exciting than toast before running. As you increase mileage, pace, and total activity time, pay attention to what you might’ve eaten before a bout of EX-GIS, and if there seems to be a pattern. This could also include meal timing, as complex meals may take more time to properly digest. There also appears to be some evidence to indicate that a large intake of fats pre-exercise could be a typical trigger for EX-GIS.

Simple carbs seem to be less likely to trigger EX-GIS, so if you’re looking for a bit more of a guarantee, sports drinks and gummy bears will probably keep you safe.

Additionally, athletes also report that over time it’s possible to become more resistant to EX-GIS, as you continue to run and train. Likely due to adaptations to exercise that either require less blood flow to working muscles at similar intensities, or more blood flow to the guts.

Last but not least, if you ever wondered why people say “never change your routine before a race” 9 times out of 10 it’s about EX-GIS. Sure, chafing from a new top or tight calves from new shoes aren’t great, but not quite as publicly devastating. If you don’t normally have a large burrito and an iced coffee for breakfast before your marathons, please see the top of this post for a peak into your future.