GI issues have a variety of symptoms including: diarrhea, nausea, vomiting, bloating, belching, cramps heartburn and bloody stools. Symptoms are more common in women, younger athletes, elite athletes and people with a history of GI issues. It is estimated to occur in 30-90% of distance runners during and/or after exercise. Complaints of GI issues differ in severity and they may cause a decline in performance and recovery.
There are three main reasons for GI problems:
- Physiological - When we exercise, depending on the intensity, blood supply to the gut may decrease by up to 80% in order to transfer more blood to the working muscles, skin and heart. This in turn may cause diarrhea, nausea, vomiting and stomach pain.
- Mechanical - Running is a high impact sport with continuous pounding. This pounding also influences the GI tract which in turn can cause GI symptoms. Therefore, runners have a tendency to have more problems than bikers.
- Nutritional - The meal timing before exercise as well as beverage and food choices may cause GI symptoms. A meal shortly before running, rich with fiber, fat and protein will cause GI symptoms because these nutrients have a slow emptying rate in the stomach. Drinking a concentrated carbohydrate beverage during or slightly before a race will cause GI symptoms. Moreover, dehydration intensifies GI symptoms. As discussed in the previous blog on alcohol and performance, drinking the night before a run several drinks can cause GI symptoms probably due to its diuretic effect.
- Note; Certain people may have a medical condition such as: celiac disease, lactose/fructose mal-absorption and irritable bowel syndrome to name a few, that makes them more susceptible to GI symptoms
Since this blog is a nutrition blog, lets talk about some nutrition strategies to prevent GI symptoms:
- Hydration, hydration, hydration - before a run, make sure you are hydrated. Focus on hydrating well throughout the day.
- Avoid beverages during or slightly before a run rich with fructose such as juice. Prefer water or if running long distance, a sports beverage with 6-8% carbohydrates such as Gatorade or Powerade.
- Avoid high fiber foods 1-2 hours pre-exercise as well as the day before a big race.
- Avoid high fat and high protein foods 1-2 hours pre-exercise
- "Train the gut" - the gut is very adaptable, therefore, train your gut by eating during your training as well as before (if activity is lower than 60-90 minutes there is no need to eat anything during and water should suffice). Experiment with foods before a training session to check what works and what doesn't.
- Avoid using non-selective, non steroidal anti-inflammatory drugs (NSAIDs) such as Aspirin and Ibuprofen as they tend to increase GI symptoms.
- Avoid lactose containing milk products if you think or know that you are lactose intolerant.
- Avoid or limit alcohol drinking before a morning run or a big race
It is very important that if you have severe GI symptoms such as bloody stools, you consult with a medical professional.
For specific guidance and assistance if you suffer from the symptoms noted above, consider consulting with a sports dietitian to help you with strategies to prevent any GI symptoms.