How to avoid GI problems on race day? Avoid milk products and high-fiber foods

By Nina Beltran | Photos by Corey Motta and Frank Luca/Unsplash

There are a lot of things to be nervous about on race day. A hyperactive, butterfly-infested stomach should be the least of them.

Gastrointestinal (GI) issues are very common in triathlon. You’ve probably heard of a triathlete who had to dig up his own porta-potty by the shore just before the swim start of a Bi3 race; or that runner who had to be creative while doing his business inside the portalet and ended up using his sock as tissue.

Another classic story is of a triathlete who had to relieve himself in a pig pen along the run route of Ironman 70.3 in CamSur in 2011. There was also a coach who had to stop by the side of the road with nothing but tall grass around as his makeshift cubicle during the cycling leg of a Tri United race. Lastly, a strong triathlete who had to bail of Ironman 70.3 Cebu in 2014 in the middle of the bike leg because of a nagging stomach pain, reflux, nausea, and vomiting.

If this sounds familiar, you are not alone. Studies have shown that GI issues affect almost all endurance athletes. Sports Science Exchange Journal reported in 2013 that long-distance triathletes who competed in extreme conditions demonstrated up to 93 percent for any one GI symptom. More alarming is that 43 percent of the triathletes have serious GI problems and seven percent abandoned the race because of GI problems.

I don’t know about you, but of all reasons to quit a race, stomach upset has to be among the worst. I’d rather quit because of bad weather, an overly challenging course, or even a flat tire. These factors are beyond our control but a nervous stomach is something that can be prevented.

What Causes GI Problems?

It’s widely recognized by experts that GI problems during endurance activities are multifactorial and highly individualized. Let me break them down for you.

Reduced Blood Flow to the Gut

During maximal exercise, to provide sufficient blood flow to the active working muscles, heart, lungs, and the skin, blood flow to the GI system may be reduced up to 80 percent (Otte et al, 2001). In turn, the gut’s digest and transmitting functions become unreliable. This makes us feel nauseous, bloated, and full, or worse, cause bouts of vomiting, abdominal pain, and diarrhea. Because of the decreased function to absorb food and regulate motility, GI reflux or heartburn may occur. The way to prevent this is to decrease workload of the GI system. Be conscious of the timing and the type of food you take, not just hours before but the week prior the race.

Mechanical Causes

The repetitive, high-impact mechanics of running and gastric jostling may contribute to lower GI symptoms such as flatulence, diarrhea, and urgency to piss or defecate. The posture of super aero or aggressive position on the bike can cause upper GI symptoms possibly due to increased pressure on the abdomen. Feeling of fullness may also result from air swallowing during swim or run when we tend to mouth-breathe. In general, the only way to reduce the effects of these mechanical causes is training.

Milk products, fiber, high fat, and high protein food must be avoided 24 hours before competition and during exercise

Nutritional Causes

The strongest influence to GI distress is food. Fiber, fat, protein, and fructose have all been associated with a greater risk. These types of food require a longer time to digest and settle in the gut. Dehydration may also exacerbate symptoms. A study by De Vrese et al (2001) have shown that intake of highly concentrated carbohydrates (from beverages with high osmolalities >500mOsm/L) and dairy products are also linked to having increased incidence.

All these risk factors should be taken into account. Milk products, fiber, high fat, and high protein food must be avoided 24 hours before competition and during exercise. During the race, try to have different sources of energy (power bars, gels, sports drink) to minimize taste fatigue.

Train Your Gut

Notice that some people can better tolerate eating compared to you? I envy those triathletes who can devour a full meal before a race without having stomach issues. I envy those triathletes who don’t need to bring tissue at every race.

The gut is highly adaptable and endurance athletes should incorporate nutritional training into their training plans. Try different foods and see what works for you. Practice nutrition strategies with your exercise at least once a week. Never try anything new on race day. The training would reduce the chances of GI distress as improved intestinal absorption is generally associated with improved tolerance of fluids and foods during exercise (Jeukendrup and Mclaughlin 2011).

Better Choices
  • Avoid milk products that contain lactose. Choose soy, rice, and almond milk instead.
  • Avoid high-fiber foods on the day or the week before competition. Fiber keeps bowel movement regular but fiber before the race day is a no-no. Increased bowel movements during exercise are not desirable and will accentuate fluid loss. Check food labels for fiber content. Choose more refined carbs such as regular pasta and white rice or bread, instead of whole grain, high-fiber cereals, and brown rice. Note that most fruits and vegetables are high in fiber. For your pre-race meal, choose tomatoes, olives, grapes, and other low-fiber fresh produce.
  • Avoid NSAIDS or non-steroidal anti-inflammatory drugs such as pain relievers. Acid reflux is a common side effect of these drugs.
  • Avoid high-fructose foods, in particular fruit-based drinks.

The gut is truly an important organ for athletes because it is responsible for the delivery of water and energy during exercise. It can either make or break your race depending on how well you’ve perfected your nutrition strategy. So to those racing this weekend or anytime soon, consider yourselves warned. Hope you have the gut for it.

Reference: Nutritional Recommendations to Avoid Gastointestinal Complaints During Exercise. Journal of Sports Science Exchange (2013) Vol 26 No 114, 1-4