“Should I go before the warm up or after…or maybe before and after?”  If you have ever run a road race, you know one of the most daunting tasks on race day is standing in line for the porta-potty.  It’s in every runner’s pre-race routine though because running on an upset stomach is no fun!  Sometimes despite your best effort however, the stomach bug will find you during an intense workout or race.  An email questionnaire was sent to over 2,000 runners following a marathon event in the Netherlands.  Of the 1,281 runners who responded, 45% complained of at least one GI symptom during the event. Why is that?  And what are some steps you can take to prevent it from happening?

According to Prade de Oliveira et al, endurance athletes may experience gastrointestinal (GI) symptoms during high intensity activity stemming from either physiological, nutritional, or mechanical causes. GI issues can affect recovery just as much as performance.1

From a physiological standpoint, during high intensity exercise your heart rate goes up, breathing gets heavier, and muscles become fatigued. In response, the body sends blood to the heart, lungs, and active muscles while reducing blood flow to other areas such as the GI tract.  In fact, the reduction of blood flow can be reduced by up to 80%!

On the nutrition side, dehydration can be a major cause of GI symptoms.  Rherer et al found that athletes may experience a weight loss of 3.5-4% during exercise which can cause GI pain.2That is why hydration beforehand is so important, if you wait until during the race to take fluids you are most likely too late! In addition, diets high in protein, fat, or fiber can cause GI symptoms as well as foods with a high concentration of carbohydrates.1  

Mechanically, posture and impact forces play a role in causing GI distress. Prade de Oliveira et al mention how the crouched position of cyclists during riding places pressure on the abdomen causing more upper GI symptoms.  In addition, the impact forces during running place the GI system in an unsettled state leading to its distress.

The good thing is that there are a few ways to reduce the risk of GI symptoms come race day!  It starts with finding the right nutrition strategy during training.  Practicing pre-race meals and race day fueling options before the real competition can help train your GI system.  Prade de Oliveira et al suggest avoiding high fiber foods leading up to race day, making sure to drink enough water when consuming carbohydrates, and avoiding nonsteroidal anti-inflammatory drugs like ibuprofen as these can cause GI issues.  

Oliveira EPD, Burini RC, Jeukendrup A. Gastrointestinal Complaints During Exercise: Prevalence, Etiology, and Nutritional Recommendations. Sports Medicine. 2014;44(S1):79-85. doi:10.1007/s40279-014-0153-2.
Rehrer NJ, Beckers EJ, Brouns F, Hoor FT, Saris WHM. Effects of dehydration on gastric emptying and gastrointestinal distress while running. Medicine & Science in Sports & Exercise. 1990;22(6):790. doi:10.1249/00005768-199012000-00010.
Ter Steege, Rinze W. F., Van DP, Kolkman JJ. Prevalence of gastrointestinal complaints in runners competing in a long-distance run: An internet-based observational study in 1281 subjects. Scand J Gastroenterol. 2008;43(12):1477-1482. http://dx.doi.org/10.1080/00365520802321170. doi: 10.1080/00365520802321170.

 

Adam Saloom, SDPT
Texas Woman's University