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Gastrointestinal discomfort

Gastrointestinal (GI) discomfort is not an uncommon problem for athletes during high intensity and endurance exercise. GI problems can be so server that they cause an athlete to cease exercise. If you’ve been training months for a race, the last reason you want for failing to reach your goals is GI discomfort! The common symptoms of GI discomfort during exercise include:


Stomach cramps








Urge to defecate

There are many causes for GI discomfort but we usually find that many incidents are a result of athletes using inappropriate hydration and fuelling strategies. Research has also shown that high intensity exercise can cause a redistribution of blood flow away from the gut alongside various hormonal and nervous activity changes that may lead to GI problems.

Athletes should carefully select the foods they choose to eat before a race and practice using them in training. Due to the time it takes to digest and process food (24-72 hours), careful consideration needs to be made about foods eaten in the few days before the race and not just on race day. A diet high in fibre and fat delays gastric emptying of foods and can cause an increase in GI problems. Foods and supplements that may cause GI problems in some individuals include:



Hypertonic drinks

High carbohydrate intake


Sodium bicarbonate



Anti-inflammatory drugs


  1. Test all food and drink intake during races in training to ensure you are comfortable with your strategy.
  2. Practice your drinking and fuelling strategy during training.
  3. Ensure you start your race hydrated but have allowed sufficient time to empty your bladder or any excess fluid.
  4. Avoid high fat and fibrous foods (e.g. beans, nuts, seeds, brown bread, fresh fruit, raw vegetables) in the days before the race.
  5. Eat your last meal ~3 hours before the race.
  6. Test your tolerance to dairy foods prior to a race. You may find it beneficial to avoid them.
  7. Test your caffeine strategy. You may find using a smaller dose beneficial or splitting your dose throughout the race.