According to research by Gatorade Sports Science Institute, up to 93% of long distance athletes experience gastrointestinal distress, most commonly known as Runners Trots, during exercise1. Symptoms vary in severity but may include bloating, flatulence, vomiting, constipation or diarrhoea. Sporting performance can be seriously impaired; Bill Rodgers, a 1970’s marathon legend once said, “More marathons are won or lost in the portable toilets than at the dinner table.” Huge numbers of athletes experience this problem, but few openly discuss it. So, we’ve decided to explore the topic for you: read on to find out more about the causes of runner’s trots and things you can do to prevent it.

What causes runner’s trots?

1. Splanchnic Hypoperfusion (reduced blood flow to your intestines)

Sounds complicated, but Splanchnic hypoperfusion simply means reduced blood flow: when you exercise, the working muscles in your arms and legs need a constant supply of oxygen-rich blood. Blood also rushes to the surface of your skin to help regulate temperature. To meet this demand, blood flow is diverted away from the gut. As a result, digestion slows and the absorption of fluids, electrolytes and nutrients are reduced causing abdominal distress and negatively impacting athletic performance2.  

Circulation - During exercise, how and where blood is pumped has a huge impact on digestion - Bimuno

2. Increased Motility (movement stimulates the digestive process)

Pounding the pavements literally jostles your insides as your body moves up and down for extended periods of time. This movement stimulates peristalsis, the wave-like contractions used to move food through the digestive tract. The increase in movement means the contents of the digestive system gets pushed through towards the rectum at a much faster pace. This results in the urge to have a bowel movement – not ideal if you’re halfway through a run.

Running keeps things moving! Exercise, in particular running, stimulates the digestive process. So the more you move, the faster waste passes through your system. - Bimuno

3. Anxiety Before a Race (your state of mind directly affects your digestive health)

The gut and the brain directly communicate with each other via the vagus nerve in the nervous system. So, when you’re brain gets nervous before a race, your gut responds.

But how?  

Firstly, stress hormones are released in the brain, activating the ‘fight or flight response’. Your body is getting ready for an attack! In response, your gut prepares to fight infection or trauma by increasing the production of inflammatory cells. This causes an imbalance in the gut environment, disrupting digestion and causing GI distress.

Butterflies in your stomach before a race? The vervous system connects the gut and the brain via the vagus nerve. Your state of mind directly affects your digestive health. - Bimuno

4. Dehydration (not enough water in the digestive system to support healthy function)

Dehydration is one of the most common causes of constipation and is often experienced post exercise. Water is vital to the digestive system; it helps keep waste moving through at a healthy rate. To restore water levels, the large intestine soaks up water from food, drying it out. This leads to hard, dry stools which are difficult to pass.

Hydrate! Dehydration is one of the most common causes of constipation. Water keeps waste moving through your intestines at a healthy rate. - Bimuno

5. Diet and Routine (what you eat and when you eat it impacts your digestive health)

High fat, high protein foods remain in your gastrointestinal tract for longer, increasing the likelihood that you will have undigested food in your stomach when you start to run. Carbohydrates require extra fluid to digest, so fluid accumulates in the gut, leading to loose stools and diarrhoea.  

Artificial sweeteners found in many energy drinks and gels contain sugar alcohols which pull fluid into the digestive tract during digestion. This can also result in loose stools and diarrhoea. Coffee can stimulate the distal colon which helps push waste out of the body. It's best to experiment with new products such as protein, energy gels and carb-loading during training periods rather than on the day of a race. Monitor your symptoms alongside your food and drink intake:  

Diet and routine - Experiment with new products during training sessions and monitor symptoms - Bimuno

How can I prevent runner’s trots?

  • Maintain hydration: drink approximately 1 litre of water per hour of exercise to replace the water you lose through sweat.
  • Stick to your routine: don’t change anything on the day of a race
  • Monitor your symptoms: experiment with new products during training sessions
  • Digest your food: allow at least 3 hours to properly digest a large meal and allow 1-2 hours to digest a small snack
  • Look after your gut: add foods which contain prebiotic fibre such as leeks, onions and artichokes. They feed the good bacteria in your gut, encouraging it to thrive.
  • Mentally prepare for races: try to relax and minimise stress prior to a race
  • Plan your route to include bathrooms! If you know where you can stop, you’ll feel less anxious and you’ll be able to just get out there and enjoy your run!
How to avoid runners trots! Here is our list on how to avoid digestive imbalance whilst running - Bimuno

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