It’s too common! Gastrointestinal discomfort is reported by up to 96% of long-distance runners during their race1.
In this context, one of the most unpleasant gastrointestinal manifestations is “runner’s diarrhea”, which occurs in some athletes either during or immediately after a run, and is more common in long-distance runners.
What is clear is that food moves faster through the gastrointestinal tract of the athletes at the given time, although the reason is not clear2. Contributing factors likely include:
- the physical disturbance of the internal organs (due to the vibrations),
- the reduced blood flow in the intestinal tract,
- changes in gut hormone secretion,
- the increased amount of food before the race or
- the intake of some new food
- anxiety and stress before the race
Often, simple dietary changes can help prevent this adverse development:
- At least one day before the run, limit or avoid high-fiber foods such as legumes, bran, fruit, and salads. If you run every day, experiment to find a tolerable level of fiber. Otherwise, just prefer to eat these foods after you’ve run rather than before.
- At least one day before running, limit or avoid sweeteners called (isomalt, sorbitol, etc.) — most commonly found in candy, gum, and sugar-free ice cream.
- For three to six hours before running, limit or avoid caffeine and high-fat foods.
- For at least two hours before you run, do not eat anything at all.
- Before, during and after running, drink plenty of fluids. Dehydration can lead to diarrhea. Avoid hot liquids, however, which can speed food through the digestive tract.
- When running, be careful with energy gels and bars. In some people, these products may contribute to diarrhea. And especially avoid introducing a new gel or bar on race day.
- If you are lactose intolerant, switch to lactose-reduced or lactose-free milk and milk products.
- Avoid non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen etc. Both of these have been shown to increase the incidence of gastrointestinal upset.
- Additionally, wear comfortable, loose clothing when running. Clothes that are too tight around the waist can make the disorders worse.
- You may also consider reducing the intensity or distance of your runs until your symptoms improve. Then gradually increase your activity as your signs and symptoms allow.
- If these tips don’t seem to help, consult a medical professional for additional suggestions.
- Costa R, Snipe R, Kitic C, Gibson P. Systematic review: exercise-induced gastrointestinal syndrome—implications for health and intestinal disease. Aliment Pharmacol Ther. 2017;46(3):246–65.
- “How can I prevent runner’s diarrhea?” By Dana Sparks,July 2021, Mayo Clinic News Network
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