Neglecting the GI system is one of the biggest mistakes triathletes make. Take charge of your discomfort with this guide.
by Kim Mueller
You just blazed the bike leg of your second IRONMAN, and are determined to carry the momentum onto the run. Instead, you are greeted with bloating, gas, and severe stomach cramps that have you doubled over on the side of the road in no time—not where you want to be en route to the coveted finish line.
If this sounds familiar, you’re not alone. Gastrointestinal, aka “gut” or “GI” disturbances, which target the upper and lower abdominal wall (see table below) have been shown to affect nearly every endurance athlete at some point during their racing career. These disturbances can range from pesky, to so severe that the athlete has to accept a DNF.
Common GI disturbances
Gut issues, despite what the name may imply or how it’s used, are defined by discomfort or abnormalities in either the lower or upper abdominal area:
|Lower Abdominal Disturbances||Upper Abdominal Disturbances|
Urgent need for toilet
Lower abdominal cramps
Causes of GI disturbances
Physiological: While the cause of GI disturbance is often multi-faceted, experts belive the primary instigator is an overall reduction of blood and oxygen to the intestines, also known as ischemia. This is compounded by the fact that other cells—namely the muscles—are also in demand. Ischemia tends to be most pronounced in prolonged strenuous exercise. Sound familiar anyone?
Nutritional: There are a host of nutrition-related contributing causes to GI distress.
→ Consuming too many fibrous foods in the days leading up and including race day, can leave residue in the gut.
→ Meals high in fat and protein can also slow digestion, making them undesirable choices the night before the race and on race morning.
→ If adequate digestion hasn’t occurred prior to the race start, unpleasant burping and vomiting can occur during the swim.
→ It’s also common for athletes to swallow air during the swim as well as when drinking from water bottles throughout the race, increasing the risk for stomach distress.
→ Consuming too much of any ingredient (carbs, electrolytes, protein, fat) without the right volume of liquid (or just too many calories in general based on oxygen available for digestion) during racing is similar to throwing too much food down your kitchen sink—it results in a clogged gut, delayed gastric emptying, and a consequent cocktail of upper and lower GI disturbances.
→ Lastly, failure to stay hydrated also does not help.
Biomechanical: An aggressive aero cycling position can also worsen upper GI disturbances as it increases pressure on the abdomen. Gastric jostling on the run tends to exacerbate lower GI disturbances, especially gas and bathroom urgencies.
For some athletes, avoiding GI disturbance completely may not be possible, due to the genetic component to such problems. The following strategies and nutritional practices, however, can certainly help lead the way to a happier gut on race day.
1) Train the gut: Triathlon should actually be called “quadrathlon,” as performance in one is so heavily impacted by the execution of all four disciplines: Swim, bike, run, and nutrition. Too many athletes focus all their attention on swimming, biking, and running, however, and begin the race vastly underprepared on the nutrition front.
Research suggests that athletes who fail to practice their nutrition intake in training are twice as likely to experience GI disturbances on race day compared to those who have. As a side note, if it’s not the same nutrition you plan on using on race day, you are not prepping your gut properly. At least once a month, try doing a mini race simulation where you practice everything nutritionally from a timing, hydration, and fueling perspective at your target race pace. It doesn’t have to be the entire distance of your goal race, but it should encompass at least a portion of it. Document your results in a training log so you can review what works and what doesn’t. Consume carbohydrates in training at a rate of 30-90 grams per hour, preferably from multiple sources (e.g., glucose and fructose). This has been shown to enhance intestinal absorption, which will improve fuel tolerance.
2) Follow a low-residue pre-race diet: For up to 72 hours pre-race, minimize residue in the diet. Click here for a list of low-residue foods.
3) Give yourself adequate pre-race digestion time: In general, allow approximately one hour for every 200 to 300 calories consumed, focusing on low-residue carbohydrates on race morning.
4) Avoid non-steroidal anti-inflammatory drugs (NSAID) and Aspirin pre-race: Chronic use of these drugs has been shown to damage the intestinal wall and increase incidence of GI disturbances.
5) Be careful with supplements: Several supplements and ergogenic aids, including caffeine at high doses, beetroot juice, and sodium bicarbonate, can increase risk for GI disturbances, so know how your body responds to a supplement prior to implementing it on race day.
6) Stay hydrated: Sip on fluids so that your urine runs pale yellow pre-race and water weight loss does not exceed two percent during racing.
Kimberly Mueller is a Registered Dietitian and Board Certified Specialist in Sports Nutrition as well as an elite endurance athlete. She has competed at both the IRONMAN 70.3 and IRONMAN World Championships. Her company, Fuel Factor, is based in San Diego.