Training: How do I deal with Runner’s Diarrhea? (part I)

Running can be distressing, especially to your gastro-intestinal tract (GI Tract). There is simply nothing like needing to find a bathroom in an emergency 18 miles deep into a long run, or crashing the Porta-potty lines at the end of a marathon, because your body has decided to let loose a flurry of something bad.

Runner’s diarrhea is unfortunately all too common. Its causes can be physical, situational or nutritional – or could be combination of all three problems. Before I jump into the causes and suggestions to deal with it, let me relate a case-study of my own which is a classic case of gastro-intestinal distress during a racing situation.

In this particular case, I was competing in Ironman Arizona in 2006. The temperature was pushing into the low 90s, so hydration was already going to be an issue. Around mile 65 on the bike course, I retrieved my special needs bag and drank a bottle of Ensure, which is a meal replacement supplement. I had used Ensure before, but for some reason within 5 miles there were dramatic gurgling sounds emanating from my stomach. In another 10 miles, I was forced into the Porta-potty and subjected it to a gush of fluid. After about 10 minutes, I was back on my bike, but my stomach was still quite upset. Over the course of the next 20 miles, I didn’t eat or drink a thing, for fear of making things worse. But knowing that I had a marathon ahead of me, I gradually started introducing plain water and then electrolyte solution and then food. I was being so careful with my hydration that I visited the Porta-potties no less than 20 times on the marathon course, but I did make it through to finish the race.

What I’d like to use this story to illustrate are the following: 1) diarrhea can strike suddenly, whether you’re a seasoned athlete or a novice; 2) even if you’ve used a food before, the particular situation may make that food intolerable to you (for example it may have been the heat in this case; 3) you must take action, such as reintroducing fluids to stave off serious dehydration once diarrhea appears, because the loss of fluid from your GI tract can lead to even further dehydration; and 4) although uncomfortable, you can often deal with diarrhea in a race, but it will take proactive action on your part to keep it from sidelining you.

What are the causes of Runner’s Diarrhea?

Diarrhea can strike for a number of reasons, include the following:
Physical motion – the jarring up and down motion of running can cause gastro-intestinal distress.
Lack of blood to the GI Tract – blood that would normally be used to digest foods and absorb fluids is diverted your working muscles during exercise, leaving the GI tract without the blood supply needed to function normally.
The presence of high-fiber foods – Foods made of insoluble fiber promote the retention of water in the GI tract, often causing diarrhea.
Nutritional issues – Your GI tract may be reacting negatively to any number of things that you have eaten. See below for more on this.
Hydration Issues – Diarrhea is both a symptom of, and a cause of, dehydration. [For more on this read this article.]
Your experience – Younger and less experienced athletes tend to suffer more from GI problems than older and more experienced athletes. In some respects the GI Tract must “get used” to the stress of exercise and usually does so over time.
Your level of training – Exercising too hard, too quickly can cause GI problems. Backing off your workout load and increasing your mileage more slowly is sometimes the answer.

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