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How To Prevent Runners Diarrhoea

Have you ever felt a sudden overwhelming need to empty your bowels after, or worse still during your run?


It could be runner's Diarrhoea.

Abdominal cramping, bloating, nausea, flatulence, heartburn, vomiting, and belching are common symptoms. But these symptoms vary hugely among runners.

Results from one study show that 53% of participants (runners) report an urge for a bowel movement while 38% report diarrhoea after running.

According to Brouns & Beckers, 1993, 30% to 50% of endurance athletes experience gastrointestinal problems! Of this percentage, 29% have impaired performance so it goes without saying that it's something runners need to pay attention to.

What causes runner’s diarrhoea?

According to Erick P de Oliveira, 2017, these are causes:

  • Reduced oxygen flow (Ischemia) to the intestines altering intestinal permeability

  • Mechanical factors - increased vibrations of the intestinal wall and bouncing movements of organs cause loosening of bowel contents; thus, the urgency to go to the loo

  • Nutrition - Drinks with above 8% carbohydrate concentration delay gastric emptying, leading to fluid shifts in the intestine; thus, resulting to runner’s Diarrhoea. This is why we recommend avoiding hypertonic drinks and gels pre or during any racing.

  • The psychological factor – pre-race jitter lead to anxiety and stress. Tim Vanuytsel et al., 2014 highlights how psychological stress causes the small intestine to increase permeability, which is associated with the secretion of stress hormones. And stress makes you feel like poo ha!

Click below and get your free macro workbook for endurance athlete's:

Methods To Prevent Runner's Diarrhoea

  1. Avoid/limit high-fibre and gas-producing foods at least 24 hours before running nonetheless, If you run daily, test for tolerable fibre level. Otherwise, eat high fibre foods like beans, cruciferous vegetables, bran, fruit, caffeine and salad after your run.

  2. Steer clear of sweeteners - sugar alcohols (e.g., isomalt, sorbitol), at least a day before running - If you know it affects you.

  3. Keep your hydration levels normal during and after the race because dehydration can cause Diarrhoea. Besides, avoid warm liquids at they can speed food movement along the digestive tract.

  4. Your pre-race or mid-race drink should have the right balance of carbohydrates. The right mix of transportable carbohydrates minimises the presence of fluids and carbohydrates in your intestine during exercise. Beverages with high carbohydrates having absorptive capacities like Maltodextrin + fructose or Glucose + fructose are ideal. Again, choose a beverage with sodium as the uptake of Glucose through GLUTs carbohydrate transporters depends on sodium.

  5. Avoid introducing a new type of energy gel or energy bar on the day of racing - it may cause Diarrhoea. Similarly, be cautious with your usual bars as they can contribute to Diarrhoea.

  6. Train your gut to accommodate carbohydrates. Begin by taking a little carbohydrate during training, and gradually increase the amount and frequency.

  7. This might increase the number of carbohydrate transporters in your gut; thus, enhancing digestion and absorption of carbohydrate during running.

  8. It might be helpful if you had a bowel movement and urinate before exercising – it just might prevent mid-run disaster. Starting with a clear colon will prevent runner's Diarrhoea.

To Sum Up

Runners trots is a very real problem amongst the running community, but there are strategies you can implement to help reduce the risk of getting caught short.

As ever with nutrition, it comes down to you as an individual and requires practice, and patience. Record what works for you, and what doesn't! To help build a steadfast strategy for your racing and training.

In need of more support with your running?

Check out ENDURE:RUN, the 12 week metabolic testing and nutrition coaching programme for the recreational runner who's looking to supercharge their running performance.


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