Are GI Issues Ruining Your Running?

Are GI Issues Ruining Your Running?


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While training for my first marathon, I had the honor of making my very first trip to a gastroenterologist.

During the second month of training, I developed some severe stomach issues. I’ll spare you the details, but I’ll say that they were scary enough that I booked an appointment ASAP. The pain and discomfort started to interfere with my training runs, and I was nervous my first marathon finish was in jeopardy. After the initial appointment, the doctor diagnosed me with ischemic colitis brought on by a mixture of taking too many Advil while running 50+ miles a week and not staying adequately hydrated. I stopped the Advil, loaded up on water, and haven’t had any issues since!

Unfortunately, the majority of runners will experience GI issues at some point. Here are the top causes, as well as some advice to make running enjoyable again!

Major Causes of GI Issues During Running


Ischemic Colitis

Ischemic Colitis occurs when blood flow to the colon is reduced or narrowed. When running, your body will start to send more blood to the muscles in your legs, where it’s usually diverted from the intestinal system. The condition is most commonly seen in people over 60, but some studies find that 20%+ of long-distance runners develop ischemic colitis. Symptoms include:

  • Pain or cramping in your belly
  • Bright red or maroon-colored blood in your stool
  • A feeling of urgency to move your bowels
  • Diarrhea

All very un-sexy and, unfortunately, all very common to anyone who’s had to find the nearest port-a-potty in the long run.



Now that we know blood is diverted away from the GI system when running, imagine compounding that issue with even mild dehydration. When dehydrated, a runner’s GI system can be overloaded so, even when fluids are consumed, they may not be properly digested and sent back up, or quickly down. Remember that you need to start hydrating for a long run days before the run and not the morning of.

Issues With Your Diet

Avoiding meat, high-fiber foods, and concentrated sports drinks/gels before runs may help alleviate GI issues mid-run. Also, consider limiting dairy products, as the protein in dairy takes a while to digest.


Running in Warmer Temperatures

One study found that, when athletes were dehydrated and running in the heat, their stomachs emptied significantly slower. The majority of these runners also reported GI issues. If you must run in the heat, as I do in Florida, here are some tips:

  • If you suspect you may be dehydrated (dark yellow urine is a good indicator), amp up your water intake and consider adding electrolyte tabs to your water while running.
  • Avoid eating within 2 hours of running. If you have to eat something, try to stick to simple, carb-based snacks under 200 calories. I usually go for a frozen waffle or a banana.
  • If the above tips don’t work, try taking some Pepto or chewing on a tum before your long runs. I’ve had many friends swear by this!

Last update on 2021-01-14 / Images from Amazon Product Advertising API

Last update on 2021-01-14 / Images from Amazon Product Advertising API

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Erica House

Erica House has her Masters in Psychology and has been teaching at the University level since 2007. She is certified as a Personal Trainer through the American College of Sports Medicine as well as a Certified Intuitive Eating Counselor. After quitting smoking and maintaining a 50 pound weight loss she became passionate about helping others on their journey to lifelong happiness and wellness.

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