Running and Lower GI Problems

Diarrhea, the unwanted urge to defecate, flatulence and other lower gastrointestinal (GI) tract issues affect many runners. A 1984 survey reported over a third of runners experienced the urge to defecate during or after running, with 10% of runners reporting that diarrhea interrupted a run. This article gathers suggestions for dealing with lower GI issues from many sources; if you have suggestions for additions or changes, please contact me.

• Running is far more likely to cause lower GI issues than exercises such as swimming, cycling or walking. This is probably due to the physical motion that jogs the contents of the digestive system up and down. A higher Cadence might help with this.
• Eating can trigger the Gastrocolic reflex to defecate. This reflex can cause problems when running, but it can also be used to empty the GI before a run.
• Try limiting high fiber foods the 24 hours before a long run.
  • Alternatively, more fiber may actually help. More fiber may help the GI tract to empty in a timely fashion (i.e. before the run). For instance, taking some fiber the night before could help the GI tract empty the next morning before the run.
• Fructose can cause diarrhea as well as bloating and flatulence. This is more of an issue when fructose is consumed in isolation than when taken as sucrose. (Sucrose is a molecule of fructose combined with a molecule of glucose.)
• Stimulants such as Caffeine and Chocolate (Theobromine) can stimulate or irritate the GI tract. Taken before the run they may help to empty the GI tract, but on a run they may cause problems.
• Avoid using NSAID drugs such as Acetaminophen (Paracetamol) or Ibuprofen as these can irritate the GI tract, especially in higher doses.
• Clothing or fuel belts that are tight around the stomach could aggravate the problem.
• Dairy foods can cause GI problems in sensitive individuals.
• Not eating anything before running works for some runners.
• Avoid foods that cause flatulence such as beans.
• Spicy foods containing Capsaicin from Chili peppers can trigger diarrhea some hours after consumption.
• Sorbitol and some other artificial sweeteners can cause diarrhea as they are not digested.
• Taking electrolyte supplements such as Endurolytes have been reported to help some runners.
• Using an anti-diarrheic such as Imodium (Loperamide) helps some runners. However other runners have found that it does not prevent the urge, only the action, which can make the problem worse. Some runners use Imodium as a preventative measure. Remember that taking any drug when running long distances involves risk and Imodium is an opoid drug, though it does not affect the central nervous system.
• Avoid ‘fat free fats’ such as Olean Olestra), which are fats that the body cannot digest. These fats can trigger Steatorrhea which involves excess fats in the feces.
• Taking Probiotics, such as Acidophilus which is found in live Yoghurt may help digestive health. If you have concerns over dairy, probiotics can be taking in other forms such as Miso or supplements.
• Following a liquid diet for 12-36 hours before a race may help.
• Keep a food diary to detect any patterns in the foods eaten and the problem.
• Aloe Vera Juice may help.
• Try cutting out different foods for a few days to see if they are the source of the problem. I found I was soy intolerant, which gave me indigestion when I ran.
• What works on one run may cause problems on another, but it may be that a food triggers a bout of diarrhea rather than being the underlying cause.
• Seek help from a nutritionist.
• Consider checking with your doctor about Irritable Bowel Syndrome, parasitic infection such as Giardiasis or other medical issues.