Sports Foods for Athletes: What Works?

Courtesy of the Gatorade Sports Science Institute

ROUNDTABLE DISCUSSION

KEY POINTS

1. Sports foods can provide an effective, convenient method for the
athlete to boost his or her nutrient needs during training and
competition.
2. Prior to using a sports food, the athlete must determine his or her
needs, and then select the appropriate food for optimizing the delivery
of the requirement.
3. Athletes must be knowledgeable about the claims made for a sports
food and avoid those with dubious claims or questionable ingredients.

INTRODUCTION

In the past couple of years, the use of functional foods by athletes and physically active individuals has risen dramatically. Our panel of experts helps to define the general types of products that are available and that may have specific benefits for the athletes’ needs. The panel also provides some guidelines for helping to determine when, how, and if a particular product may be of benefit to the athlete.

1. What are the differences between the high-carbohydrate or energy drinks and the conventional fluid- replacement beverages?

Coyle: Conventional fluid-replacement beverages are lower in carbohydrate concentration and are designed to provide fluid, carbohydrate, and electrolytes rapidly. Energy drinks are more concentrated, typically containing 20-25% carbohydrate, and are designed to pack in as much carbohydrate energy as possible with no concern for rapid replenishment of fluid. Fluid-replacement beverages usually contain sugars such as sucrose, glucose and fructose to provide the sweetness that encourages drinking. The highly concentrated energy drinks usually contain maltodextrins as the carbohydrate source to prevent sweetness from being too high.

Terrados: The needs of the athlete help to differentiate when the two types of drinks are used. During exercise in which dehydration may be the limiting factor in performance, fluid delivery is critical. Sweat rates of 2-3 L per hour (about 2-3 quarts per hour) are quite possible. The combined effects of progressive dehydration and a rising body temperature pose a considerable threat to the athlete. In such cases, the hydration beverage with multiple transportable carbohydrates (i.e., sugars that are rapidly absorbed in the small intestine) is the optimal for meeting the twin aims of providing a source of carbohydrate fuel to supplement the body’s limited stores and of supplying water to replace the losses incurred by sweating
during exercise. With extended endurance events (Ironman triathlons, very long cycling races, etc.), athletes might occasionally opt for the drinks with higher carbohydrate concentrations (20%) even though gastric emptying and intestinal fluid absorption will be slowed. All in all, the high-carbohydrate products would be more beneficial to use after training and competition to speed recovery.

Orbeta: In Asia, people generally prefer beverages that are sweeter. However, when we counsel athletes, we always emphasize how choice of the correct sports drinks before, during and after competition may spell the difference between winning and losing. In addition to a proper level of carbohydrate, fluid-replacement drinks should contain sodium, which has been shown to stimulate drinking in athletes athletes during exercise. The electrolytes may be less important in the high-carbohydrate energy drink consumed as a part of pre-event meals or after training.

O’Connor: Individuals who find it difficult to eat the quantities of food that are required to balance the energy that is expended in growth and training may find a liquid meal provided by the energy drink easier to consume than solid food. This is especially true when they are feeling full, or before training when most prefer to train on an empty stomach. Liquid meals may also be useful pre-event as they reduce the need to defecate. Liquid meals have been used extensively in ultra-endurance events such as the Race Across America (RAAM). In sports where making weight is required before competition, extensive use of liquid meals 24 to 48 hours prior to competition may assist weigh-in by providing adequate nutrition yet reducing bowel residue and body weight by 0.5-1.0 kilogram. The high-carbohydrate beverages may be especially convenient during heavy training, carbohydrate loading, or traveling to regions where there is limited access to high-carbohydrate foods. In areas where the food hygiene may be a concern, high-carbohydrate powder made up with bottled water may be the safest meal option.

Reinaldo Garcia: Some high-energy drinks may have non-nutritional compounds such as caffeine or ephedrine derivatives. Consequently, the “energy” provided occurs via a pharmacological stimulation of the central nervous system. From a hydration standpoint, caffeine has the negative side effect of increasing loss of fluid through urine due to its diuretic effects. To make matters worse, if the caffeine or ephedrine content of the drink is too high, doping regulations may be violated. For these reasons we advise the athletes on the Venezuelan national teams to use conventional sports drinks before, during, and afterexercise and to avoid energy drinks containing caffeine.

2. What are your guidelines to athletes who wish to use energy gels?

Terrados: Energy gels can be used to assure adequate glucose intake, so, depending on the size of the gel package, at least one per hour of training or competition (with fluid ad libitum) is what I advise. In sports where glycogen depletion is one of the mechanisms of fatigue, additional carbohydrates ingested by the athlete can enhance glycogen synthesis or help maintain muscle levels by providing an alternative carbohydrate source, i.e., blood sugar, to help the athlete continue his performance.

O’Connor: No controlled research exists to compare the effectiveness of energy gels with that of fluid replacement beverages, sports bars, or solid foods during exercise. However, I sometimes recommend the use of gels in addition to a fluid replacement beverage, especially when the need for carbohydrate is greater than the need for fluid. Open-water swimming in cold water is a good example where exercise is prolonged and the need for carbohydrate is greater than the need for fluid. In this situation, gels may be easier to consume than solid foods especially as swimmers often experience a swollen, sore throat from the prolonged exposure to salt water. Gels may also be useful as a between-event, low-fiber, carbohydrate snack that is easy on the stomach. This may be helpful for gymnasts and dancers who prefer to avoid consumption of bulky solid foods that may cause bloating. It is important for athletes to recognize that the gels do not replace the need to consume fluid and electrolytes.

Berning: The use of gels is more of a personal choice than it is a science. Some athletes opt for the gels over liquids and food because gels provide a concentrated dose of carbohydrate in a very dense form that is easy to digest and light to carry. Others hate gels because of their dislike of the texture, sweetness, and intensity of the flavor. As for the science, a preliminary report on gels shows similar glycemic response when compared to liquid or solid foods with the same amount of carbohydrates, although the liquid and gel carbohydrates induced a slightly faster rise in glucose in the first 15 minutes of exercise with a corresponding increase in insulin that was higher with the liquid carbohydrate. An energy gel composed of 25 grams of carbohydrate taken with 200 ml of fluid was able to maintain blood glucose levels during a two hour run at 70% of V02 max when compared to a placebo. While it appears that gels may be effective in providing energy for exercise, the biggest challenge may be taking in enough fluid along with them. Most athletes already compete in a state of dehydration. If they do not drink enough fluid when consuming a gel they may slow down the absorption of both the carbohydrate and water resulting in poor performance.

Reinaldo Garcia: I agree with Dr. Berning’s concern. During exercise, especially in hot and humid climates, the greatest need is to replace fluids lost during sweating. For that reason, sports drinks provide practical advantages over the gel-plus-water routine. If an athlete wants to use carbohydrate gels during exercise, it should be matched with an adequate amount of water. For example, for a 1.4 oz. gel pack the athlete should drink approximately 500 ml of fluid. I also recommend that the athlete examine the gel’s electrolyte content, which may promote fluid retention.

Coyle: Energy gels usually contain 25 grams of maltodextrin per squeeze pack. We recommend that endurance athletes consume 30-60 grams of carbohydrate per hour of exercise, so this translates into sucking down 1-2 packs per hour. Research indicates that this amount of carbohydrate is effective for delaying fatigue during prolonged exercise compared to taking nothing at all. To reiterate Dr. Garcia’s comments, the gels containing concentrated carbohydrate provide virtually no fluid. Because fluid replacement and carbohydrate supplementation are known to benefit endurance performance, sufficient fluid must be ingested. Therefore, people can either take the gels with sufficient fluid or they can drink conventional fluid-replacement beverages already containing the proper mixture of carbohydrate, electrolytes, and fluid.

3. What about the supplements for muscle building? Does the science show that these or other supplements, such as creatine, increase muscle mass and strength?

Orbeta: It is always a challenge as a sports nutritionist dealing with body builders, powerlifters and strength athletes because of their view that emphasizes the use of extra protein, amino acid supplements, and now
creatine. The research literature to date does not provide substantial or convincing evidence that the well-defined muscle bulk and strength are a direct result of creatine or amino acid supplementation. When dealing with strength and power athletes, we should teach them to follow the basic ground rules of good performance nutrition, to be open minded to what scientists say about meal plans during training.

Coyle: I agree that the science has yet to document unequivocally that creatine or protein powers actually increase muscle mass or strength. The only data that I have seen demonstrating a benefit of creatine indicated a reduced fatiguability during repeated exercise bouts. That is different from increasing muscle mass or strength.

Reinaldo Garcia: The continued popularity of protein supplements is amazing considering the lack of scientific evidence for any benefit to muscle growth. Moreover, the emphasis on protein makes the athlete forget that adequate energy intake, the proper training stimulus, and rest have much more of an impact on muscle growth. With respect to creatine supplements, the proposed increase in body mass is most likely a function of water retention. With some athletes living by the philosophy that if a little is good, more must even be better, the risk is that athletes consume massive doses without knowing whether any long-term negative effects will develop.

O’Connor: Creatine supplementation has gained tremendous popularity amongst strength-training athletes. An increase in the maximum weight lifted for one repetition (1RM) for the bench press strength and in the total number of repetitions completed at 70% 1RM has been reported following 28 days of creatine loading. The improvements in performance were partly due to training alone. Unfortunately, the study design could not isolate the added benefit of creatine supplementation. A recent study using a double-blind experimental design investigated the effect of creatine supplementation on the ability to perform bench press repetitions and repeated jump squats. The results suggested that performance improved within the range of 10-20%. However, the question remains whether those subjects were truly blind to the treatment once they realized that they gained weight, an effect of creatine that can not be masked.

Berning: I have a similar interpretation of the literature on creatine. Most studies reporting no differences in performance after loading are field studies— those that most closely simulate the performance needed in sports. It does raise a concern that improvements in performance have been mostly found in laboratory studies where the opportunity to analyze data on a per-second basis is greater than out in the field. Several studies using creatine supplementation have shown improvements in short bouts of activities (knee extensions and sprint cycling) however, the statistical analysis has revealed improvements in certain segments of the exercise bouts while performance in the latter stages of exercise has not been improved. Additionally, because of the weight gain associated with creatine supplementation, certain athletes may have a harder time maintaining weight. Athletes such as pitchers may have trouble performing due to the biomechanical changes that occur with weight gain and muscle swelling. Catchers or any other athlete that have up and down movements throughout an athletic event may find it more difficult to perform with the added weight. Recently, the FDA issued a warning about creatine usage and encouraged individuals to consult their physicians. The warning results from creatine’s possible role in three deaths and two cases of seizures among athletes.

4. Do you recommend using solid foods such as sports bars during competition?

Berning: The recommendation of solid foods depends on the athlete and the type of exercise. It is difficult for a swimmer to eat an energy bar, chew, swallow and swim fast. It is much easier for swimmers to consume carbohydrates in a liquid form. Bicyclists competing in a 100-mile race can eat just about any form of carbohydrate depending upon how well they tolerate such feedings. It appears that athletes that compete in all-day events will a eat combination of solid forms of carbohydrate in between competition and liquid forms of carbohydrates just before or during competition. The glycemic index of the food seems to be important before the competition and after exercise. A low-glycemic food would theoretically be beneficial before exercise so as not to raise blood glucose too high. A high-glycemic food should be ingested after exercise to help restore muscle glycogen. It is imperative that the composition of an energy bar be predominantly carbohydrate.

Coyle: Solid food or sports bars are not necessary during exercise unless the duration is longer than 2 hours and people become hungry or want more concentrated carbohydrate during exercise. Adding protein or fats to a sports bar to be eaten during exercise are inconsistent with the goal of delivering energy. Fat requires 2-4 hours to even get into the blood and thus be available as an energy source. Little protein is used for energy and even then, it is a slow process. Some products claim that the addition of protein or fat to a carbohydrate bar will blunt the blood glucose and insulin responses and thus the carbohydrate in the bar will have less of an effect on reducing the body’s own mobilization of fat. This is misguided thinking. The addition of protein to a carbohydrate bar will actually raise the insulin response and suppress fat mobilization and fat burning. Energy bars should be high-glycemic. That is their purpose, to put glucose into the blood.

Reinaldo Garcia: Many energy bars qualify as a healthy snack and can be useful when athletes train and compete more than once a day or for prolonged periods of time within a day. If the bar is used as a snack, it should contain carbohydrate, proteins, fat, vitamins and minerals to help the athlete to cover all the nutrient needs of the day.

O’Connor: I recommend solid foods or bars during competition for individuals who complain of feeling hungry when participating in prolonged exercise or between heats or trials which may span over an entire day. Solid foods also provide variety and give athletes a taste break from liquid energy alone. I recommend moderate-to-high glycemic carbohydrates to prevent a long delay in absorption. During most exercise situations, nutrients other than carbohydrate (e.g., fat and protein) probably have a role in enhancing the palatability of the food.

5. Are there any additives in sports foods that you should recommend that athletes avoid? How can athletes, coaches and athletic trainers separate fact from fiction when it comes to nutritional supplements?

O’Connor: Bee pollen is one to be careful of because it contains proteins that can trigger serious allergic reactions, and even death in a small number of cases. Excessive consumption of particular vitamins or minerals may reduce the bioavailability of other nutrients. Minerals like calcium, iron and zinc are a good example where excessive consumption of one can reduce the absorption of the others. Nutrients interact with each other and good nutrition relies on a balance of all nutrients. This balance is difficult if not impossible to achieve with excessive supplementation. Checking your intake against the recommended daily intake (RDI) is a good way to gauge how much extra you are taking in supplement form. In Australia, The Australian and New Zealand Food Authority set guidelines for the maximum levels of certain nutrients in sports foods to protect consumers from taking too much of any one nutrient. Unfortunately, this protection is lost with tablet or capsule supplements where individuals can easily consume excessive quantities of individual nutrients.

Terrados: In spite of the clear evidence demonstrating the negative effects of dehydration on exercise performance and the positive effects of fluid and carbohydrate ingestion, most athletes do not drink sufficient volumes to match fluid and carbohydrate needs during exercise. Athletes must replace the fluids and electrolytes in the post-exercise period to maintain exercise capacity when repeated bouts of exercise have to be performed the same day or the next day. The need for replacement will obviously depend on the extent of the losses incurred during exercise, but will also depend on non-exercise losses; athletes living in hot environments will experience substantially increased fluid losses even when not exercising. Excessive intake of fluids with a low sodium content can induce hyponatremia during exercise of long duration. The ingestion of plain water in the post-exercise period also results in a rapid fall in the plasma sodium concentration and in plasma osmolality, which suppress the thirst and shuts off drinking before rehydration is complete.

Reinaldo Garcia: We recently had an unfortunate experience at the international regional games. A weight-lifting athlete bought a supplement that was suppose to be natural but contained Ma Huang, a derivative from ephedra that is prohibited for use by the International Olympic Committee. This athlete tested positive for the drug and lost his gold medal. We now educate athletes so that they can identify foods and supplements to avoid. Also, we advise examining the credentials of people who promote the supplements, the nutrition facts of the products, and the credibility of the scientific research.

Coyle: I recommend avoiding products containing hidden ingredients, especially those originating from plants and roots that claim to be stimulants. I advise avoiding buying supplements in health food stores and encourage athletes to question claims that are based on testimony.

Orbeta: Health food stores are often glorified and overrated “food boutiques” that offer no solid scientific evidence about performance benefits except for anecdotal claims. My advice to coaches, trainers, athletes and team physicians is as follows:

a. Invest your money in good foods. Nothing can take the place of well-chosen foods taken in variety of ways and in the recommended nutrient ratio (lots of complex carbohydrates, moderate protein, low-fat, high in fiber). Supplements are more expensive than real foods and provide fewer nutrients overall.
b. Be cautious when you hear or see high-tech terms or pseudo-medical jargon such as detoxifying your body, balancing your chemistry, strengthening your immune system, oxygenating your blood, improving your metabolic function, and high thermogenic power.
c. Consult knowledgeable health professionals who possess the proper credentials. Know how to read labels of products before buying them, and know what the ingredients mean.
d. Realize that there are no short cuts to glory to be found in bottles, miracle pills, and mysterious potions.

Berning: There are several ingredients in sports foods, some sports drinks, or in supplement form that should be avoided. Dehydroepiandrosterone (DHEA) and a new supplement called Androl-6 should be avoided. These substances, which are similar in structure to testosterone, have not been shown to build muscle or strength in athletes. However, they may produce negative side effects because of the size of the doses that are consumed. The NCAA and NFL have banned the use of DHEA. Ma Huang and Jin Bu Huan should not be included in the supplements. Jin Bu Huan has caused life-threatening respiratory problems. Ma Huang is an amphetamine-like substance often used in weight-loss concoctions. The combination of
Ma Huang and caffeine has been implicated in more than 100 injuries and several deaths. Other popular supplements have been added to sports foods but they have not been scientifically proven to be effective. These include: carnitine, chromium, Co-enzyme Q, Gamma-oryzanol, ginseng, lecithin, medium chain triglycerides (MCT), and omega-3 fatty acids. The list goes on. If you are not sure about certain substances then seek assistance from someone in the field such as a Registered Dietitian or Exercise Physiologist. Contact the American Dietetic Association’s practice group of sports nutritionists (SCAN), the American College of Sports Medicine, or the equivalent professional societies in your region for more information.