Does running mess with your guts?

A tricky and somewhat delicate topic to tackle, but a real problem for some. Exercise does provide immediate benefits for your gastrointestinal system. There appears to be a dose-response relationship between exercise intensity and health. Mild to moderate levels of exercise can help to protect against colon cancer and constipation, as well as other conditions. It can improve digestion and elimination through strengthening muscles of the abdomen and stimulating intestinal muscles to help move things along more quickly. However, intense exercise has been associated with heartburn, gastric reflux, nausea, vomiting, abdominal pain, diarrhea and even gastrointestinal bleeding. Exercise sometimes slows down digestion as energy is conserved for exercise activity. Gut ischemia, or a lack of blood supply through various causes, is thought to be at the heart of some of the gastrointestinal problems that people experience when exercising.

Research reported in this paper seems to find that those that exercise the most intense - elite athletes - are hit particularly hard by these problems. About 25 to 50% of these athletes are affected so badly by symptoms of gastrointestinal distress that it can put them off training or competing. A dehydrated state can also make these symptoms worse.

Interestingly, the frequency of these symptoms seems to be twice as high for endurance runners than those participating in other endurance sports such as swimming or cycling, and one to three times more frequent in elite athletes compared to those participating in more recreational exercise..

Here's what you can do to avoid negative side effects of exercise if these are a problem for you:

  • To be ultra-safe, allow two hours after a meal before you exercise and do not exercise on a full stomach. I always leave an hour at least, but if you continue to have problems, try longer
  • Practice light exercise to improve the efficiency of the digestive system
  • Check your meal composition, water intake, and medications - if these aren't right, it can make the problem worse
  • Avoid caffeine before exercise. It can sharpen you up, but loosen you up too - it irritates the bowel
  • Light exercise such as yoga and pilates can also improve digestive system functions by reducing stress and anxiety levels, which can cause digestive disorders, too.

Good luck!