This is an excerpt from Nancy Clark's Sports Nutrition Guidebook-5th Edition.
Go by Your Gut
Preexercise foods that settle comfortably can enhance stamina, endurance, strength, and enjoyment. But many people are afraid that preexercise food will result in an upset stomach, diarrhea, and undesired pit stops. Of course, eating too much of the wrong kinds of foods can cause intestinal problems. But with the possibility that any preexercise food can create intestinal chaos, your desire for pancakes make be overruled by the threat of stomach problems.
Each person has unique food preferences and aversions, so no one food or magic meal will ensure top performance for everyone. Frank, a competitive runner, avoids any food within four hours of training or competing. Otherwise, he has horrible stomach cramps. Kristin, a loyal exerciser at a health club, thrives best on a plain bagel an hour before her morning routine. "It absorbs the stomach juices and settles my stomach." Sarah, a gymnast and eighth-grade student, snacks on a banana before practice sessions but on nothing before a competition. She gets so nervous that she can't keep anything down. "I make sure I eat extra the day before a competition," she said.
Choices of what to eat before exercising vary from person to person and from sport to sport - there is no single right or wrong choice. My experience has shown that each athlete needs to learn through trial and error during training and competition what works best for his or her body and what doesn't work. From day 1 of your training program, you need to train not only your heart, lungs, and muscles, but also your intestinal tract to tolerate preexercise food.
To train your intestinal tract to tolerate preexercise fuel, start with a cracker or a sip of a sports drink; gradually add more until you can enjoy about 200 to 300 calories within the hour before you work out. Keep in mind the following predisposing factors that might trigger GI problems:
- Type of sport. Cyclists, swimmers, cross-country skiers, and others who exercise in a relatively stable position report fewer GI problems than do athletes in running sports that jostle the intestines.
- Training status. Untrained people who are starting an exercise program report more GI problems than do well-trained athletes who have built up a tolerance to exercise. If you are a novice who is experiencing GI distress, gradually increase your training volume and intensity so that your body can adjust to the changes.
- Age. GI problems occur more frequently in younger athletes than in veterans. The younger athletes may be less trained and possibly have less nutrition knowledge and experience with precompetition eating. Veterans, on the other hand, have had the opportunity to learn from years of nutrition mistakes.
- Gender. Women report more GI problems than men do, particularly at the time of their menstrual periods. The hormonal shifts that occur during menstruation can contribute to looser bowel movements.
- Emotional and mental stress. Athletes who are tense are more likely to report that food in the stomach lingers longer and settles like a lead balloon.
- Exercise intensity. During easy and even moderately hard exercise, the body can both digest food and comfortably exercise. But during intense exercise, the shift of blood flow from the stomach to the working muscles may be responsible for GI complaints.
- Precompetition food intake. Eating too much high-protein and high-fat food (such as bacon and fried eggs or a burger and French fries) shortly before exercise can cause GI problems. Tried-and-true low-fat, carbohydrate-rich favorites (such as oatmeal or bananas) that are part of your day-to-day training diet are a safer bet.
- Fiber. High-fiber diets intensify GI complaints. If you are eating large amounts of bran cereal or high-fiber energy bars, try cutting back for a week to see whether you feel better.
- Caffeine. Some athletes try to enhance their performance by drinking a larger-than-usual mug of coffee but end up with an upset stomach, diarrhea, and substandard performance.
- Gels and concentrated sugar solutions. Highly concentrated sugar solutions consumed during exercise may cause stomach distress. Don't confuse the high-carbohydrate recovery drinks (about 200 calories per 8 oz, or per 240 ml) with low-carbohydrate fluid replacers.
- Sugar-free foods with sorbitol. Maybe you have trouble digesting certain kinds of carbohydrates and need to see a dietitian who specializes in FODMAP diets (fermentable oligo-, di-, and monosaccharides and polyols; see appendix A).
- Level of hydration. Dehydration enhances the risk of intestinal problems. During training, be sure to practice drinking different fluids on a regular schedule (about 8 oz, or 240 ml, every 15 to 20 minutes of strenuous exercise) to learn how your body reacts to water, sports drinks, diluted juice, and any fluids that you will be drinking during competition.
- Hormonal changes. The digestive process is under hormonal control, and exercise stimulates changes in these hormones. For example, postmarathon levels of GI hormones tend to be two to five times higher than resting levels. These hormonal changes can result in food traveling faster through the digestive system and explain why some people experience GI problems regardless of what they eat.
- Irritable bowel syndrome. An estimated 10 to 20 percent of Americans suffer from irritable bowel syndrome. That number includes a lot of athletic people who may be sidelined by their symptoms during exercise. Yet, in general, exercise can improve symptoms (Johannesson et al. 2011).
- Undiagnosed celiac disease. The same people who routinely have "sensitive stomachs" and bowel issues find that exercise exaggerates the problem. Marta, a 17-year-old high school runner, kept getting sidelined with fecal urgency during cross-country races. She came to me for help with figuring out the GI problem. When I asked about her medical history, she mentioned that she had an underactive thyroid, three broken bones in the past four years, and recurrent anemia. Her father had colon cancer, his mother had severe osteoporosis, and her aunt had diabetes. All of these medical issues raised a red flag for celiac disease.
Eat the Right Foods at the Right Time
The trick to completing your workout with energy to spare is to fuel up with the right foods at the right time before the event. Figure 9.1 shows the steps of digestion. For workouts less than 60 to 90 minutes, the preexercise snack should be predominantly carbohydrate because it empties quickly from the stomach (as compared to protein and fat) and becomes readily available to be used by the muscles. But before extended exercise such as a long run or bike ride, adding peanut butter to that bagel will contribute sustained energy. Here are some suggestions for different types of events at different times of the day:
Turning food into fuel.
Time:8:00 a.m. event, such as a road race, swim meet, or intense spin (stationary cycling) class
Meals: Eat a carbohydrate-based dinner, and drink extra water the day before. On the morning of the event, at about 6:00 or 6:30, have a light 200- to 400-calorie meal (depending on your tolerance), such as yogurt and a banana or a granola bar and a latte, and extra water. Eat familiar foods. If you want a larger meal, consider eating between 5:00 and 6:00 a.m.
If your body cannot handle any breakfast before early-morning hard exercise, eat your breakfast before going to bed the night before. A bowl of cereal, bagel with peanut butter, or packets of oatmeal can help boost liver glycogen stores and prevent low blood sugar the next morning.
Time:10:00 a.m. event, such as a bike race or soccer game
Meals: Eat a carbohydrate-based dinner such as a chicken stir-fry with extra rice, and drink extra water the day before. On the morning of the event, eat a familiar breakfast by 7:00 a.m. to allow three hours for the food to digest. This meal will prevent the fatigue that results from low blood sugar. Popular choices are oatmeal with nuts and raisins, a bagel with peanut butter and a banana, and yogurt with Grape-Nuts and berries.
Read more from Nancy Clark's Sports Nutrition Guidebook, 5th Edition by Nancy Clark.