Avoid the dreaded runner’s trots with the right prevention and you’ll fly on the run

How to prevent runner's trots

One of running’s most embarassing ailments, the runner’s trots have unstuck many an Ironman attempt (Illustration: Peter Greenwood)

Runner’s trots (diarrhoea while running) can be extremely embarrassing and equally uncomfortable, yet it’s a surprisingly common occurrence, particularly in marathon running and Ironman.

It’s blamed on gastrointestinal (GI) distress, which stems from causes including reduced blood flow to the GI tract, stress or anxiety, the effects of impact while training, poor posture on the bike and poor pre-race and race-day nutrition and dehydration.

“Studies show exercise reduces blood flow to the digestive organs,” says nutritional therapist at Pure Sports Medicine, Henrietta Bailey. “This reduces intestinal absorption of foods, causing nutrients to accumulate in the GI tract, and bloating and diarrhoea.”


  1. Reduce your fibre intake by avoiding large quantities of salads and vegetables in the 24-48 hours prior to a race. While fibre is essential for a healthy diet, it may contribute to GI distress on race day
  2. Plan your pre-race and race day nutrition in advance. Find out what works for you and then stick with it. Don’t try anything new in the week before the race or on the day of the race itself. Try the nutrition that will be provided on the course – if you don’t get on with it, you’ll need to be self sufficient
  3. Keep hydrated. This aids blood flow to your muscles to digest food. If you’re dehydrated your intestine won’t absorb food properly or empty efficiently, which will lead to GI distress
  4. Experiment with carbs. Some athletes find that fructose (fruit sugar) causes cramping and gas. Bailey recommends trying maltodextrin, which you can tolerate in a higher carb solution without GI issues. You can also train your gut to absorb more carbs, so be sure to use sports nutrition in training as well as race day
  5. Watch your intensity – the harder you go, the less blood there is around the gut to aid absorption. This is why it’s so important not to overdo it on the bike during longer events

Find out more about common triathlon injuries or read more about how to avoid triathlon injuries on TriRadar.