Stomach Issues while racing – Possible causes and solutions

If you have ever dealt with a stomach issue while racing, then you have experienced the gut wrenching, painful, disappointing feeling it brings. Once you are dealing with a stomach issue, there is little you can do and no quick solution. Slowing down to allow digestion to take place is one solution but to stop racing may be the only answer if the pain is severe. The best way to avoid stomach issues, otherwise known as the dreaded gut rot, is to prevent it. In this article we will discuss a few aspects of racing that can lead to stomach issues.


Poor pacing can easily lead to stomach issues, especially when you are competing in long duration events. The longer the event, the more need for food and water and the more important pacing becomes, especially for events that last from 7-10 hours. Too many intense surges during these longer events can easily lead to stomach issues. When you surge and work a higher intensity, even for a few minutes, you create an increased need for blood flow to the working muscles and to cool the body. That leaves less blood flow for digestion.


Think about it – when you are walking you could easily eat a sandwich and possibly a tall glass of flavored drink to wash it all down and continue to walk for a long duration with no stomach issues. But if you increased your intensity and started to run at a fast pace for 3-4 miles, it would be very hard if not impossible to eat the same quantity of food, especially if you were to continue a fast pace for a longer duration.

So, too many surges within a long duration race can lead to a shutdown or at the least a slowdown of digestive ability, leaving undigested food and water in the stomach, leading to stomach issues. The best strategy, and the fastest strategy, is to pace very steady from start to end with as few surges as possible.


Ingesting too many carbohydrates and or too much protein can be another possible cause for stomach issues. Taking in protein for races that are less than 12 hours in duration is up for a lot of debate these days, but it is agreed upon that taking in some carbohydrates is a benefit to performance, especially for events lasting more than 2-3 hours. There is balance between consuming enough to benefit your performance compared to too much, which could possibly hurt your performance.


A solution containing carbohydrates empties far slower from the stomach compared to plain water. In the book Waterlogged by Dr. Tim Noakes1, he explains this: “Generally, about two-thirds of any volume of water ingested is emptied within the first ten minutes; two-thirds of what remains is then emptied within the next ten minutes. In contrast, as little as about 25% of an energy rich solution would be emptied in the same time.” With the rate the stomach can empty in mind, it is clear to see how easy it is to take in too much fluid, among other things such as solid foods, creating a backup in the stomach leading to stomach issues.

You are going to lose weight through the loss of water and fuel while exercising and during competition. The thought of replacing the fluids and fuel used while exercising to maintain a zero negative balance is being challenged more now than ever before and may not be possible. The fastest people in the race are the most dehydrated and have experienced the most weight loss. Research from 297 Ironman triathletes showed no evidence that a loss in body mass lead to impaired performance. Weight loss of 5-7% is common for the top elite marathon runners, and in a study done on ultra-marathoners in the “marathon Des Sables,” the athlete with the greatest body mass loss was the fastest2.


Preparing well and listening to your body is the key to preventing stomach issues during competition. As more research is unveiled, it shows the importance of listening to when you’re thirsty to drink, and hungry to eat. Trying to stay ahead of when you need to eat and drink may just compound problems you will feel later in the race. Use every race to practice, learn from, and continue to dial it all in over time.

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