no. 9.362

Nutrition for the Athlete

Quick Facts...

• Athletes achieve peak performance by training and eating a variety of foods.
• Athletes gain most from the amount of carbohydrates stored in the body.
• Fat also provides body fuel; use of fat as fuel depends on the duration of the exercise and the condition of the athlete.
• Exercise may increase the athlete's need for protein.
• Water is a critical nutrient for athletes. Dehydration can cause muscle cramping and fatigue.

Becoming an elite athlete requires good genes, good training and conditioning and a sensible diet. Optimal nutrition is essential for peak performance. Nutritional misinformation can do as much harm to the ambitious athlete as good nutrition can help.

Carbohydrates

Athletes gain most from the amount of carbohydrates stored in the body. In the early stages of moderate exercise, carbohydrates provide 40 to 50 percent of the energy requirement. Carbohydrates yield more energy per unit of oxygen consumed than fats. Because oxygen often is the limiting factor in long duration events, it is beneficial for the athlete to use the energy source requiring the least amount of oxygen per kilocalorie produced. As work intensity increases, carbohydrate utilization increases.

Complex carbohydrates come from foods such as spaghetti, potatoes, lasagna, cereals and other grain products. Simple carbohydrates are found in fruits, milk, honey and sugar. During digestion, the body breaks down carbohydrates to glucose and stores it in the muscles as glycogen.

During exercise, the glycogen goes back to glucose and is used for energy. The ability to sustain prolonged vigorous exercise is directly related to initial levels of muscle glycogen. The body stores a limited amount of carbohydrate in the muscles and liver. If the event lasts for less than 90 minutes, the glycogen stored in the muscle is enough to supply the needed energy. Extra carbohydrates will not help, any more than adding gas to a half-full tank will make the car go faster.

For events that require heavy work for more than 90 minutes, a high-carbohydrate diet eaten for two to three days before the event allows glycogen storage spaces to be filled. Long distance runners, cyclists, cross-country skiers, canoe racers, swimmers and soccer players report benefits from a precompetition diet where 70 percent of the calories comes from carbohydrates.

According to the Olympic Training Center in Colorado Springs, endurance athletes on a high-carbohydrate diet can exercise longer than athletes eating a low-carbohydrate, high-fat diet. Eating a high-carbohydrate diet constantly is not advised. This conditions the body to use only carbohydrates for fuel and not the fatty acids derived from fats.

For continuous activities of three to four hours, make sure that glycogen stores in the muscles and liver are at a maximum. Consider taking carbohydrates during the event in the form of carbohydrate solutions. The current recommendation is a 6 to 8 percent glucose solution.

You can make an excellent home-brewed 7.6 percent sports drink with reasonable sodium amounts. Add 6 tablespoons sugar and 1/3 teaspoon salt to each quart of water. Dissolve sugar and cool. The salt translates into a sodium concentration of 650 mg/liter. This small amount is good for marathon runners.

Electrolyte beverages can be used if the athlete tolerates them, but other electrolytes are not essential until after the event. Experiment during training to find the best beverage for you.

Eating sugar or honey just before an event does not provide any extra energy for the event. It takes about 30 minutes for the sugar to enter the blood stream. This practice may also lead to dehydration. Water is needed to absorb the sugar into the cells. Furthermore, sugar eaten before an event may hinder performance because it triggers a surge of insulin. The insulin causes a sharp drop in blood sugar level in about 30 minutes. Competing when the blood sugar level is low leads to fatigue, nausea and dehydration.

A diet where 70 percent of calories comes from carbohydrates for three days prior to the event is sometimes helpful for endurance athletes. (See Table 1 for a sample menu.) Water retention often is associated with carbohydrate loading. This may cause stiffness in the muscles and sluggishness early in the event. A three-day regimen minimizes this effect. The previously suggested seven days of deprivation/repletion is not recommended due to increased risks of coronary heart disease. In addition, electrocardiograph abnormalities may occur and training during the deprivation phase may be difficult.

Water

Water is an important nutrient for the athlete. Athletes should start any event hydrated and replace as much lost fluid as possible by drinking chilled liquids at frequent intervals during the event. Chilled fluids are absorbed faster and help lower body temperature. (See Table 2.)

Fats

Fat also provides body fuel. For moderate exercise, about half of the total energy expenditure is derived from free fatty acid metabolism. If the event lasts more than an hour, the body may use mostly fats for energy. Using fat as fuel depends on the event's duration and the athlete's condition. Trained athletes use fat for energy more quickly than untrained athletes.

Fat may contribute as much as 75 percent of the energy demand during prolonged aerobic work in the endurance-trained athlete. There is evidence that the rate of fat metabolism may be accelerated by ingesting caffeine prior to and during endurance performance. However, insomnia, restlessness and ringing of the ears can occur. Furthermore, caffeine acts as a diuretic and athletes want to avoid the need to urinate during competition.

Protein

After carbohydrates and fats, protein provides energy for the body. Exercise may increase an athlete's need for protein, depending on the type and frequency of exercise. Extra protein is stored as fat. In the fully grown athlete, it is training that builds muscle, not protein per se. The ADA reports that a protein intake of 10 to 12 percent of total calories is sufficient. Most authorities recommend that athletes eat 1 to 1.5 grams protein per kg of body weight per day. (A kilogram equals 2.2 pounds.) Adolescents and body-builders often follow the recommendation of 1.5 grams of protein per kilogram of ideal body weight.

Japanese researchers demonstrated that "sports anemia" may appear in the early stages of training with intakes of less than 1 gram/kg of body weight per day of high quality protein. To calculate your protein needs, divide your ideal weight by 2.2 pounds to obtain your weight in kilograms. Then multiply kilograms by the grams of protein recommended.

A varied diet will provide more than enough protein as caloric intake increases. Furthermore, Americans tend to eat more than the recommended amounts of protein. Excess protein can deprive the athlete of more efficient fuel and can lead to dehydration. High-protein diets increase the water requirement necessary to eliminate the nitrogen through the urine. Also, an increase in metabolic rate can occur and, therefore, increased oxygen consumption. Protein supplements are unnecessary and not recommended.

Vitamins and Minerals

Increased caloric intake through a varied diet ensures a sufficient amount of vitamins and minerals for the athlete. There is no evidence that taking more vitamins than is obtained by eating a variety of foods will improve performance. Thiamin, riboflavin and niacin (B vitamins) are needed to produce energy from the fuel sources in the diet. However, more than enough of these vitamins will be obtained from the foods eaten. Carbohydrate and protein foods are excellent sources of these vitamins. Furthermore, the B vitamins are water soluble and are not stored in the body. Some female athletes may lack riboflavin. Milk products not only increase the riboflavin level but also provide protein and calcium. The body stores excess fat-soluble vitamins A, D, E and K. Excessive amounts of fat-soluble vitamins may have toxic effects.

Minerals play an important role in performance. Heavy exercise affects the body's supply of sodium, potassium, iron and calcium. To replenish sodium lost through sweating, eat normally following the competition. Avoid excessive amounts of sodium. Eating potassium-rich foods such as oranges, bananas and potatoes supplies necessary potassium. Salt tablets are not recommended.

Sweating naturally increases the concentration of salt in the body. Salt tablets take water from the cells, causing weak muscles. They also increase potassium losses. Potassium is important to help regulate muscle activity. Salt added to beverages during endurance events may be helpful.

Iron carries oxygen and is another important mineral for athletes. Female athletes and athletes between 13 and 19 years old may have inadequate supplies of iron. Female athletes who train heavily have a high incidence of amenorrhea and thus conserve iron stores. Iron supplements may be prescribed by a physician if laboratory tests indicate an iron deficiency. Excess iron can cause constipation. To avoid this problem, eat fruits, vegetables, whole grain breads and cereals.

Calcium is an important nutrient for everyone. Female athletes should have an adequate supply of calcium to avoid calcium loss from bones. Calcium loss may lead to osteoporosis later in life. Dairy products, especially low-fat choices, are the best source of calcium.

The Pre-Game Meal

A pre-game meal three to four hours before the event allows for optimal digestion and energy supply. Most authorities recommend small pre-game meals that provide 500 to 1,000 calories.

The meal should be high in starch, which breaks down more easily than protein and fats. The starch should be in the form of complex carbohydrates (breads, cold cereal, pasta, fruits and vegetables). They are digested at a rate that provides consistent energy to the body and are emptied from the stomach in two to three hours.

High-sugar foods lead to a rapid rise in blood sugar, followed by a decline in blood sugar and less energy. In addition, concentrated sweets can draw fluid into the gastrointestinal tract and contribute to dehydration, cramping, nausea and diarrhea. Don't consume any carbohydrates one and a half to two hours before an event. This may lead to premature exhaustion of glycogen stores in endurance events.

Avoid a meal high in fats. Fat takes longer to digest.

Take in adequate fluids during this pre-game time. Caffeine (cola, coffee, tea) may lead to dehydration by increasing urine production.

Don't ignore the psychological aspect of eating foods you enjoy and tolerate well before an event. However, choose wisely -- bake meat instead of frying it, for example.

Some athletes may prefer a liquid pre-game meal, especially if the event begins within two or three hours. A liquid meal will move out of the stomach by the time a meet or match begins. Remember, include water with this meal.

Regardless of age, gender or sport, the pre-game meal recommendations are the same. (See Table 3.)

Maintain nutritional conditioning not only for athletic events, but all the time. A pre-game meal or special diet for several days prior to competition cannot make up for an inadequate daily food intake in previous months or years.

Lifelong good nutrition habits must be emphasized. Combine good eating practices with a good training and conditioning program plus good genes, and a winning athlete can result!

Sources of Information and Materials

From Colorado State University Extension

Request other fact sheets from The Extension Resource Center, Colorado State University, 115 General Services Building, Fort Collins, CO 80523-4061; (970) 491-6198; Single copies are $1.00. Fact sheets can also be downloaded from the Internet at www.ext.colostate.edu.

• 9.312, Water-Soluble Vitamins
• 9.315, Fat-Soluble Vitamins
• 9.324, Vegetarian Diets
• 9.353, Dietary Guidelines for Americans
• 9.354, Sodium in the Diet
• 9.355, Potassium and Health
• 9.356, Iron: An Essential Nutrient

Other Resources

• Winning Sports Nutrition, video and training manual, University of Arizona, 1995.
• Sports Nutrition Guidebook, by Nancy Clark, Leisure Press, 1990.
• For recipes, see Athlete's Kitchen by Nancy Clark, published by Bantam Books, 1983.
• Nutrition for Athletes: A Handbook for Coaches produced by the American Alliance for Health, Physical Education and Recreation, 1201 Sixteenth Street, NW, Washington, DC, 20036.
• Order a copy of You: A Guide to Food, Exercise and Nutrition from Colorado Dairy Council, Inc., 12450 North Washington Ave., P.O. Box 33120, Thornton, CO, 80233-0120; telephone (303) 451-7711; cost $1.

Other Resources

• Sports Nutrition Guidebook, by Nancy Clark, Leisure Press, 1996.
• Nutrition for Athletes: A Handbook for Coaches produced by the American Alliance for Health, Physical Education and Recreation, 1201 Sixteenth Street, NW, Washington, DC, 20036 or visit their website at www.aahperd.org.
• Order a copy of Eating for Peak Performance or Competition Nutrition from Colorado Dairy Council, Inc., 12450 North Washington Ave., Thornton, CO, 80241; telephone (800) 274-6455.
• Visit the American Dietetic Association's website at www.eatright.org for reliable nutrition information or to find a registered dietician.
• Visit the American College of Sports Medicine's website at www.acsm.org for a variety of information and brochures.

References

• Advances in Sports Medicine and Fitness, Volume 2, 1989.
• Nutrition for Fitness and Sports, Melvin Williams; Brown, Benchmark, 1995.
• Nutrition for the Recreational Athlete, Catherine Jackson, editor; CRC Press, 1995.

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