Gut friendly fuel

It's race day. You are feeling well. You've put in the miles and mentally you're ready for the challenge. But there is one concern: Those urgent bathroom stops that seem to be coming on with increasing frequency. Not to mention the stomach cramps. Slowing down no longer seems to help, and stopping every two miles is definitely going to ruin your race. Maybe it is better to skip breakfast completely?

Gut cramps or gastrointestinal distress (GI distress for short), is actually a group of symptoms that is caused by exercise. You may have experienced GI distress as one or more of these symptoms: heartburn, nausea, vomiting, urgent need for a bowel movement, gastrointestinal bleeding or abdominal cramping. No matter what your GI symptoms are, the outcome will be the same: a reduction in performance.

Among long distance runners, the frequency of exercise related GI distress has been reported to be as high as 25 percent during training and 50 percent during marathons. Cyclists also experience a variety of GI symptoms. However, the problems are highest among runners due to the significant mechanical impact of the sport.

Physiologic factors

Endurance athletes understand the concept of gradual increases in training stress to stimulate muscle adaptation. Unfortunately, however, the digestive system is not similarly trainable. That is to say, no matter how much you train, the GI system does not improve in its capacity to digest food during exercise. Quite simply, the gut is not an athletic organ.

During exercise blood flow to the stomach and digestive system is shunted away to the working muscles, effectively shutting down the digestive process. When we attempt to eat and exercise, the result can be a host of GI symptoms that can only be relieved by slowing down or ceasing activity.

While the GI tract itself is not able to make fitness adaptations, adequate training that improves aerobic fitness will allow more blood flow at submaximal exercise intensities. That is why food or drinks tested during training which seem to be tolerated, may cause symptoms when exercise intensity is higher during a race. Since it is not possible to change your physiology, let's take a look at what can be done with a change in diet for racing.

The pre-race meal

Your food choices, timing of meals and hydration status can dramatically improve or worsen GI symptoms you experience during exercise.

Ideally, if a meal is eaten before exercise, it has time to work its way through the digestive machinery and is out of your GI tract before you start moving. A typical breakfast meal can take three hours to digest, with simple sugars moving through the system the quickest at about 10 calories per minute, and fat, the slowest, at two calories per minute. Protein lies somewhere in between, moving through at approximately four calories per minute.

Since high intensity muscular work is primarily fueled by carbohydrates, it makes sense to keep pre-exercise meals high in carbohydrates so that blood sugar is maintained and glycogen stores are adequate. Protein is used minimally during exercise as a fuel, and is needed only in small amounts prior to exercise, if at all.

Keep choices low in fat, so that the digestive process is not slowed. Small amounts of fat add satiety and flavor to a meal. However, most of us have adequate fat stores to tap into for energy, so there is no need to load up on a gut-busting breakfast of bacon or sausage to provide extra calories.

One of the most common mistakes athletes make on race day is to gauge the size of their pre-race meal on the distance of the event. This faulty reasoning can lead to a host of GI problems as excess amounts of food will tax the body, demanding blood flow to the stomach while muscles in the periphery are screaming for fuel. As a general guide, aim for roughly one-third of your calorie expenditure to be consumed prior to exercise.

For example, a 190-pound male could consume a breakfast of about 450 calories, while a 120-pound female could fuel adequately with 200 calories. Of critical importance during the race would be a focused nutrition plan, where carbohydrate fuel was supplied using the guide of 30 grams to 60 grams per hour. In events that last longer than two hours, the addition of protein can be helpful, but it should be in liquid form such as whey isolate.

Best carbohydrate fuel

Unprocessed high carbohydrate foods are becoming more popular with health conscious athletes. Food producers have begun to replace high fructose corn syrup with other natural sugars, such as organic brown rice syrup. One label from a well known sport company which now creates a raw (cold-processed) snack bar claimed their product had "healthy carbohydrates for consistent, reliable and long-lasting energy" and that it was sweetened only with whole food sweeteners, including organic dates, organic raisins and low Glycemic Index organic agave nectar.

Another popular pre-exercise breakfast is the homemade fruit smoothie. Typical ingredients include bananas, berries, yogurt and sometimes whey protein powder. Loaded with anti-oxidants and natural sugars, it certainly seems like a great choice.

Although the movement towards less processed foods clearly has health benefits, how does it affect the athlete with GI distress?

The goal in choosing the right food for a race day is primarily to provide fuel for the muscles without causing GI symptoms. As a rule, these types of food should have a blend of simple sugars to speed the delivery of the sugar from the stomach, through the intestinal wall, and into the blood stream. The label on a sport gel or hydration drink should include ingredients such as maltodextrin (a.k.a glucose polymers), fructose, brown rice syrup, and/or cane sugar. Products that contain more fructose than glucose should be avoided (see sidebar) because fructose sugar is not rapidly absorbed into the bloodstream.

Few people cannot absorb more than 25 grams of fructose, even at rest, without experiencing some GI symptoms such as gas, bloating and possibly diarrhea. But there are other types of sugars that are also not well tolerated.

They are known as FODMAPS, which include fructans, and other fermentable oligo-, di- and mono-saccharides and polyols (sugar alcohols), such as erythritol, mannitol (and other ingredients that end with -tol) commonly added as artificial sweeteners in commercial foods. The physiological consequences of the malabsorption of FODMAP's include an increased osmotic load, a source of energy to fuel rapid bacterial fermentation, changes in gastrointestinal motility and the alteration of the bacterial flora. Research has shown that when fructose is combined with sorbitol, there is an additive effect resulting in greater malabsorption associated problems.

Other race day mistakes

Aside from choosing the wrong type of sugar, other common race day mistakes are over- or under-hydration, and using solid food during intense exercise. Hydration guidelines are essentially just that, guidelines. Athlete should experiment and keep records of how much fluid they consume during training to individualize their needs. Dehydration further reduces blood flow to the GI tract, increasing the likelihood of GI related problems. Conversely, too much fluid in the stomach will cause cramps and nausea.

The same goes for consuming solid foods. The reduction of blood flow to the stomach during exercise greatly slows down digestion, and solid foods will sit in the stomach much longer than when eating at rest or at very low intensity level.

Let's review again some of the food choices an athlete might make. The healthy, raw sports bar? No. It is loaded with fructose from dried fruits and has agave nectar as a sweetener. With 9 grams of fat per bar from those healthy nuts, it is very likely to cause GI distress symptoms since it will be slowly digested.

How about that morning fruit smoothie? Since it is made with fruit, it contains a high amount of fructose sugar as well as fiber. That would not be an ideal choice for a race, as the type of fruit and amount of the serving would affect GI tolerance.

While there are wide differences in individual tolerance for foods consumed during exercise, no one is immune to GI problems. What your best friend is using may not work for you. Always test foods and products during training to avoid being surprised - and disappointed - on the day of a race. After you cross the finish line, there will be plenty of time to celebrate with your favorite foods.

Donna Marlor, MA, RD, CSSD, is a registered dietician specializing in nutrition for endurance exercise and weight management. She offers motivational coaching and behavioral skills training to change eating patterns. Marlor is a consultant to the Olympic Education Center in Marquette, Michigan, and works with many individual athletes from novice to elite. A former collegiate alpine and Nordic skier, Marlor still enjoys master's level competition as a skier and runner as well as spending time with her family and chocolate Lab in the Upper Peninsula. She can be reached via www.DonnaMarlor.com and at 906/360-9049.