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Race-day refreshments

[This article originally appeared in the October 2000 issue of Northwest Runner magazine.]

"And now," said the head track coach, "Coach Behr would like to say something."

Coach Behr stepped forward, looked around at the crowd of athletes gathered in front of him, cleared his throat, and said: "You aren't worth a damn without a good breakfast!" And then he stepped back. End of speech.

Those nine words, uttered at an otherwise uneventful team meeting, comprised the entirety of Coach Behr's advice to the team in my four years of college track. The man was nothing if not succinct. But is breakfast really a necessity for athletes hoping to perform their best? And while we're on the subject of race-day nutrition, what should athletes consume during and after a long, hard workout or competition? The following article will attempt to answer these questions using the best scientific data currently available to us.

Before the race

Let's start with breakfast. Is it OK to compete on an empty stomach following an overnight fast? Well, one study (Flynn et al., Journal of Applied Physiology 67: 2066-71, 1989) found that when trained male cyclists were fed either 4 or 8 hours prior to a 2-hour cycling test, they performed equally well in both cases. However, no less than five other well-controlled studies (Neufer et al., Journal of Applied Physiology 62: 983-8, 1987; Sherman et al., Medicine and Science in Sports and Exercise 21: 598-604, 1989; Wright et al., Journal of Applied Physiology 71: 1082-8, 1991; Chryssanthopoulos & Williams, International Journal of Sports Medicine 18: 543-8, 1997; Maffucci & McMurray, International Journal of Sport Nutrition and Exercise Metabolism 10: 103-13, 2000) have reported that subjects who ate a high-carbohydrate meal 3 or 4 hours before exercise outperformed those who fasted for 6 or more hours on various cycling and running protocols lasting anywhere from 35 to 290 minutes. The evidence in favor of eating breakfast before a long-distance event therefore appears to be pretty solid. On the other hand, the influence of a morning meal on success in shorter (e.g., 5-kilometer) races has not been systematically studied to date.

A variation on the breakfast question is this: is it helpful to eat a high-carbohydrate snack 30 to 60 minutes before exercising? Early work by David Costill and colleagues (Costill et al., Journal of Applied Physiology 43: 695-9, 1977; Foster et al., Medicine and Science in Sports 11: 1-5, 1979) suggested that snacking in the 30- to 60-minute time window could cause hypoglycemia (a drop in blood sugar) during exercise and potentially hinder performance. However, since that time, many other studies (reviewed by Hawley & Burke, British Journal of Nutrition 77: S91-103, 1997, and by Williams & Chryssanthopoulos, World Review of Nutrition and Dietetics 82: 33-45, 1997) -- including some carried out in Costill's lab -- have indicated that small pre-race snacks either improve or have no effect on endurance performance. Thus, although the threat of hypoglycemia remains, it is generally not an obstacle to racing well. In fact, Williams & Chryssanthopoulos (1997) have noted that most transiently hypoglycemic athletes are unaware of their hypoglycemia -- i.e., a brief drop on blood sugar at the start of exercise does not make them feel tired or light-headed.

How about that morning cup of coffee? Most scientists (Spriet, International Journal of Sport Nutrition 5: S84-99, 1995; Clarkson, Sports Medicine 21: 393-401, 1996; Van Soeren & Graham, Journal of Applied Physiology 85: 1493-1501, 1998; Applegate, International Journal of Sport Nutrution 9: 229-39, 1999) agree that caffeine gives a boost to male endurance athletes, though studies on women are lacking. Urinary caffeine levels of greater than 12 micrograms per milliliter -- which a 150-pound person would achieve by drinking approximately 6 cups of coffee -- are a violation of International Olympic Committee rules (Spriet, 1995). However, doses under the legal limit improve athletes' ability to run or cycle at a given pace for 40-70 minutes (Graham & Spriet, Journal of Applied Physiology 71: 2292-8, 1991).

As a side note, the reason for caffeine's effectiveness was originally thought to involve the release of fatty acids into the bloodstream. However, caffeine has been shown to improve treadmill running even in doses that don't raise blood fatty acid levels (Graham & Spriet, Journal of Applied Physiology 78: 867-74, 1995), so we still aren't sure exactly why it works. It should also be remembered that caffeine is a diuretic; thus, those who use it should take care to keep themselves well-hydrated.

During the race

The athlete's main nutritional goals during a long workout or race are to keep his/her body supplied with fluids and carbohydrates. For these things to be useful to the body, they must pass from the stomach to the small intestine and then be absorbed across the intestinal wall into the bloodstream. Therefore, it makes sense to consume fuels that move quickly from the stomach into the intestine and then are rapidly absorbed by the blood.

According to a recent review (Maughan & Leiper, Canadian Journal of Applied Physiology 24: 173-87, 1999), concentrated energy drinks do not meet these criteria; they are slow to reach the intestine and slow to deliver water to the blood once they get there. Studies disagree on whether dilute sports drinks such as Gatorade get to the intestine as fast as pure water; once in the intestine, however, the water in Gatorade seems to be absorbed faster than pure water (Gisolfi et al., American Journal of Physiology 258: G216-22, 1990; Ryan et al., Journal of Applied Physiology 84: 1581-8, 1998). Thus, considering the process as a whole, Gatorade-like beverages are probably about as effective as pure water in keeping the body hydrated, and they offer the additional advantage of supplying carbohydrates and electrolytes.

With this background in mind, we can now ask whether dilute sports drinks aid performance more than water does. Numerous investigations (reviewed by Coggan & Swanson, Medicine and Science in Sports and Exercise 24: S331-5, 1992, and by Hawley & Burke, British Journal of Nutrition 77: S91-103, 1997) have confirmed that carbo-containing electrolyte solutions such as Gatorade are in fact superior to water in exercise bouts lasting one hour or longer. In addition, several studies (Sasaki et al., International Journal of Sports Medicine 8: 261-5, 1987; Ball et al., Interational Journal of Sport Nutrition 5: 151-8, 1995; Nicholas et al., Journal of Sports Sciences 13: 283-90, 1995; Davis et al., International Journal of Sport Nutrition 7: 261-73, 1997; Davis et al., International Journal of Sports Medicine 20: 309-14, 1999) have reported that Gatorade-like drinks delay fatigue in more intense athletic tasks lasting less than 60 minutes. However, these latter studies were all conducted on subjects who had fasted overnight. Thus, whether athletes who have eaten breakfast can benefit from Gatorade during relatively short races is unclear.

If sipping Gatorade mid-race is beneficial to performance, how about chowing down on gels or PowerBars? As Owen Anderson states in the most recent issue (volume 16, number 4) of Running Research News, one can benefit from eating gel or similar foods, but one must drink the right amount of water along with the gel to make sure that the resulting mixture is neither too concentrated nor too dilute. "Take in too much water, and you end up with a hypotonic sports drink in your gullet which delivers too few carbs to your leg muscles. Take in too little water, and you concoct a syrupy goo within your intestines which actually drags in water from surrounding tissues and spurs diarrhea," he explains. "It's far easier to simply use sports drink thoughout the race."

Another practical issue concerns the end of your race or workout. Let's say you only have 20 minutes of exercise to go; is it worth tanking up on fluids one last time? The data of Maughan et al. (Experimental Physiology 75: 419-21, 1990) show that, like water, Gatorade-like beverages begin to enter the blood within a few minutes of being drunk. The take-home message here is that marathoners should think twice before skipping an aid station at mile 24.

After the race

The primary goals of post-race nutrition are to replenish the body's supply of water, electrolytes (primarily sodium), and carbohydrates. In addressing the issue of post-race hydration, we can again ask whether Gatorade and similar drinks recharge the body more effectively than water, and again the answer is yes. When large amounts of pure water are imbibed, one's bodily fluids become very dilute, and the body reacts by releasing much of the just-ingested water as urine. The sodium and potassium in sports drinks replace what is lost in sweat, thus restoring the body's supply of these ions and allowing it to "hang on" to the water that is consumed simultaneously (Nose et al., Journal of Applied Physiology 65: 325-31, 1988; Shirreffs & Maughan, Exercise and Sport Sciences Reviews 28: 27-32, 2000).

While the articles just cited focus on what to drink after exercise, the same ideas can be applied to pre-race hydration as well. In other words, drinking an electrolyte solution rather than pure water before a race will help insure that, at the start of the race, most of this fluid will still be in your body rather than in your toilet. It's also worth noting that, although ions are important for fluid retention, you don't have to get them in liquid form. As Maughan et al. (European Journal of Applied Physiology 73: 317-25, 1996) have pointed out, eating sodium-containing food and washing it down with pure water rehydrates the body just as well as drinking Gatorade. (Once you're done running, achieving the perfect ratio of food to water is no longer quite so critical.)

Finally, to restock the body's carbohydrate stores, one obviously must take in carbohydrates. A carbo-rich meal with some protein and fat appears to stimulate the synthesis of muscle glycogen (a storage form of carbohydrate) just as effectively as a pure-carbo meal, assuming the two meals contain the same number of total calories (Tarnopolsky et al., Journal of Applied Physiology 83: 1877-83, 1997; Roy & Tarnopolsky, Journal of Applied Physiology 84: 890-6, 1998; Carrithers et al., Journal of Applied Physiology 88: 1976-82, 2000; van Loon et al., American Journal of Clinical Nutrition 72: 106-11, 2000; Jentjens et al., Journal of Applied Physiology 91: 839-46, 2001). Likewise, it doesn't seem to matter whether the carbohydrate comes in solid or liquid form (Keizer et al., International Journal of Sports Medicine 8: 99-104, 1987; Reed et al., Journal of Applied Physiology 66: 720-6, 1989). What does seem to matter is the glycemic index (GI) of the food being consumed. The GI of a food is a measure of how quickly its carbohydrates get into the bloodstream; the higher the GI, the quicker the absorption process. (For examples, please see the table accompanying this article, adapted from Burke et al., International Journal of Sport Nutrition 8: 401-15, 1998.) Three fairly recent studies (Burke et al., Journal of Applied Physiology 75: 1019-23, 1993; Jozsi et al., International Journal of Sports Medicine 17: 373-8, 1996; Kiens & Richter, American Journal of Clinical Nutrition 63: 47-53, 1996) indicate that high-GI foods such as glucose and potatoes refuel muscle glycogen stores more completely than low-GI foods such as pasta and beans. Thus, if the rapid restoration of glycogen is a priority -- as when one has to do multiple workouts or races in a short period of time -- it would be prudent to emphasize high-GI foods in one's post-race meals.

In summary, race-day nutrition is a bit more complicated than Coach Behr made it out to be. Nevertheless, with a careful look at the scientific literature and some careful planning, you can make your next race -- and the one after that -- a bit easier.

Glycemic Indices of common foods

Food Glycemic Index
corn flakes84
jelly beans80
bread (white or wheat)70
soft drink68
one-minute oats66
muffins (cake-style)62
ice cream61
orange juice57
ripe banana52
baked beans48
multigrain bread45
all-bran cereal42
flavored yogurt33
unripe banana30
kidney beans27
red lentils26

Where can I get these great journals?

One of my reasons for writing this column is to expose readers to a resource they might not otherwise be aware of, namely, the vast body of scientific literature on exercise. This stuff can be frighteningly technical and is therefore usually read only by scientists; however, it is also generally more accurate and more thorough than what you find elsewhere. Thus, if you care deeply about training and/or nutrition, I would encourage you to read this literature yourself -- perhaps with the help of a scientifically-minded friend, if science isn't your thing.

Assuming that you want to peruse the Journal of Applied Physiology and other such page-turners, where should you go? Your best bet is a university medical library such as the U.W. health sciences library, which houses a superb collection of exercise-related journals. This library is open to the public, has a user-friendly layout, and is staffed by courteous, knowledgeable people.

Those who prefer to obtain their information via the web may wish to check out PubMed. PubMed is a comprehensive and easy-to-use searchable database of biomedical research articles. For example, if you wanted to obtain a listing of papers authored by G. J. Crowther in 1997, you would simply type "Crowther GJ 1997." PubMed also provides links to the websites of individual journals, some of which allow you to download their articles free of charge.

Good luck and happy reading!

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