HomeNewsIntestinal Distress: Gutting It Out

    Intestinal Distress: Gutting It Out

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    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, preventing intestinal distress is a topic of interest to athletes with finicky guts.
    Here is some information that will help you fuel well before and during exercise, while reducing the risk of gastrointestinal (GI) distress. For more, you can read The Athlete’s Gut by Patrick Wilson or listen to this podcast.

    • Being anxious about intestinal issues can exacerbate the problem. So stay calm and 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, pre-competition 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, talk to 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 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 because of 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 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, apple sauce), 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 (except 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. (Experiment during training first to be sure the low FODMAP foods settle well.) Low FODMAP foods include bananas, grapes, cantaloupe, potato, rice quinoa, maple syrup, and cheddar and Parmesan cheeses. For more information about FODMAPS, go to

    • Fatty foods (butter, cheese, nuts) tend to leave the stomach slowly and are metabolized slower than carb-rich foods. If you’ll 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 exertion. A banana or slice of toast will digest more quickly and be more available for fuel.

    Eating fatty foods on a regular basis can speed 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 undereat during training. This includes dieters trying to lose weight and athletes with anorexia. Undereating 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 being less available for fuel). Slowed intestinal motility easily leads to constipation, a common problem among undereating 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 consume a lot of fiber, which 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.

    • Since each athlete has a unique GI tract, experiment during training to learn what works best. Eat wisely–and enjoy miles of smiles.

    Sports nutritionist Nancy Clark, M.S., R.D., counsels both casual and competitive athletes in the Boston area (Newton; 617-795-1875). Her best-selling Nancy Clark’s Sports Nutrition Guidebook can help you eat to win. For more information, visit

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