By Nancy Clark, MS, RD — While some athletes have cast iron stomachs and few concerns about what and when they eat before they exercise, others live in fear of pre-exercise fuel contributing to undesired pit stops during their workouts. Be it stomach rumbling, a need to urinate or defecate, reflux, nausea, heartburn, or side stitch, how to prevent intestinal distress is a topic of interest to athletes with finnicky guts. Here are tips to help you fuel well before/during exercise while reducing the risk of gastro-intestinal (GI) distress. For more in-depth information, you might want to read The Athlete’s Gut by Patrick Wilson or listen to this podcast: https://www.scienceofultra.com/podcasts/16
Stay calm. Being anxious about intestinal issues can exacerbate the problem. Think positive. Trust that your gut is adaptable and trainable. Record what, when, and how much you eat, as well as the duration and intensity of your exercise. Use that data to help you figure out what foods and fluids settle best. Building body trust can reduce anxiety—and that can reduce GI issues. That said, precompetition nerves can affect any athlete, regardless of GI hardiness!
Athletes in running sports are more likely to suffer GI issues than, say bicyclists or skiers. With running comes intestinal jostling; the longer the intestines are jostled, the higher the risk of upset. Ultra-runners know this too well…
If you experience gut issues every day—even when you are not exercising, you want to talk with a GI doctor. Celiac disease, Crohn’s, ulcerative colitis, and blood in your stool need to get checked out now! They are serious issues and differ from exercise-induced GI problems.
The higher the intensity of exercise, the higher the risk of intestinal distress. Add heat and anxiety to intense exercise, and many athletes experience transit trouble. During hard workouts, blood flow diverts away from the gut to transport oxygen and glucose to the working muscles and carry away carbon dioxide and waste products.
Low intensity training that can be sustained for more than half an hour is less problematic. The GI tract gets adequate blood flow, can function relatively normally and is able to digest, absorb, and metabolize pre-exercise fuel. Athletes tend to have fewer GI issues on easy training days, given better blood flow to the intestines, lower body temperature and less anxiety.
Carbohydrate is the easiest-to-digest fuel before and during exercise. Carbohydrate gets broken down into simple sugars in the stomach, then absorbed into the bloodstream from the small intestine. Specific transporters carry each sugar molecule (such as glucose or fructose) across the intestinal wall. Hence, consuming a variety of carb-based fuels helps minimize a “backlog” if all the transporters for, let’s say, fructose get called into action.
With training, the body creates more transporters to alleviate any backlog. That’s one reason why you want to practice event-day fueling during training sessions. Your body gets the chance to activate specific transporters. The foods and fluids you consume before and during training should be the ones you’ll use for the event. Some popular carb-based pre-and during-exercise snacks include fruits (banana, applesauce), vegetables (boiled potato, roasted carrots), and grains (sticky rice balls, pretzels, pita)—as well as commercial sports foods (sport drinks, gels, chomps).
Athletes who experience gas and bloat want to familiarize themselves with FODMAPs —Fermentable (i.e., gas-producing) Oligo-, Di-, Mono-saccharides And Polyols. These are sugars and fibers that some people have trouble digesting. Commonly eaten sport foods high in FODMAPs include milk (apart from lactose-free milk), bread, pasta, onions, garlic, beans, lentils, hummus, apples, and honey.
By choosing a low FODMAP diet for a few days before an important event, an athlete might be able to reduce, if not avoid, digestive issues. (Of course, first, experiment during training to be sure the low FODMAP foods settle well!) Low FODMAP foods include bananas, grapes, cantaloupe, potato, rice quinoa, cheddar and Parmesan cheeses, and maple syrup. For more information on FODMAPS, refer to www.KateScarlata.com.
Fatty foods (butter, cheese, nuts) tend to slowly leave the stomach and are metabolized slower than carb-rich foods. If you will be exercising for only one to two hours, think twice before reaching for a handful of nuts or a chunk of cheese for a quick fix before you exercise. A banana or slice of toast will digest quicker and be more available for fuel.
Eating fatty foods on a regular basis can speed-up gastric emptying a bit but you won’t burn much pre-exercise dietary fat during your workout unless you are an ultra-athlete who will be exercising for more than three hours. In that case, a bagel with nut butter or cheese will offer long-lasting fuel.
Some athletes chronically under-eat during training. This includes dieters trying to lose weight, and athletes with anorexia. Under-eating can impair GI function; the gut slows down with inadequate fuel. Delayed gastric emptying means food stays longer in the stomach and can feel “heavy” during exercise (as well as is less available for fuel). Slowed intestinal motility easily leads to constipation, a common problem among under-eating athletes.
Highly active athletes, such as Tour de France cyclists and ultra-runners, need to consume a large volume of food to support performance. If they are eating “healthy” foods before and during endurance exercise, they can easily consume a lot of fiber —and that can easily contribute to rapid transit. Endurance athletes needing a high calorie diet often benefit from eating some so-called less-healthy foods (such as white bread, white rice, cookies, candy) for low-fiber muscle-fuel.
Given each athlete is has a unique GI tract, be sure to experiment during training to learn what works best. Eat wisely—and enjoy miles of smiles.
