Dietary Goals for Improved Performance

Exclusively prepared for ASL Swimmers by Dr. Ron Moody




Protein & Amino Acids

What to drink and how much?

What to eat before swimming?

What to eat during swimming?

What to eat after swimming?

What to eat to improve performance?

Sample Menu

Sample Pre-event Menu

Overtraining Syndrome






-Vitamins and others




Carbohydrate is one of the most important nutrients to athletic performance. Carbohydrate plays the major role in supplying your brain and body with power.   Exercising with low levels of carbohydrate leads to fatigue. Maximizing glycogen stores (stored carbohydrate) is one of the primary goals of sports nutrition.  Consuming carbohydrates during endurance exercise can postpone fatigue and prolong peak performance.  The proper diet and endurance training influences the amount of glycogen stored in muscle and the time it takes to exhaustion. A high carbohydrate diet can raise the initial muscle glycogen concentration and cause a greater time to exhaustion. Diet provides the body with the needed fuels, while training promotes muscle storage of more carbohydrate.  The body also learns to improve its utilization of fuel.  An individual that is more fit uses less glycogen, is better able to conserve the limited glycogen stores in the body, and utilizes more fat as a fuel source during endurance events.

Simple carbohydrates are commonly known as sugars. Sources of simple carbohydrates include table sugar, candies and other sweets, sodas and bakery goods. These foods provide empty calories, i.e., calories that supply no vitamins and minerals and should therefore be minimized.  Complex carbohydrates include all the complex starches and fiber, such as those found in grains, cereals, breads and starchy vegetables like potatoes, corn, peas and beans. Milk, fruit and vegetables also contain complex carbohydrate.  Complex carbohydrates contain many essential nutrients and are the body's most effective source of energy to the athlete. Complex carbohydrates increase glycogen stores more efficiently than sugars, or simple carbohydrates.  Complex carbohydrates are ideal because they are quickly digested and absorbed into the bloodstream, leaving the stomach quickly so there is less chance of indigestion and nausea during the event.  Carbohydrates should make up the largest portion of the athlete's diet. Research suggests that to maintain adequate carbohydrate stores during heavy training, carbohydrate intake should range from 7-10 grams/kg of body weight/day or 55-70% carbohydrate.  Athletes who train exhaustively on successive days, or who compete in more prolonged endurance events, would benefit from a diet that contains 65% to 70% of total calories from carbohydrates.


Fats, like carbohydrates, are used by the body for fuel and are essential for the absorption of certain vitamins. The most important role of fat is to spare carbohydrate (which are in limited supply) use in exercise of long duration and low intensity.  Fat is a valuable metabolic fuel for muscle activity. Endurance training significantly increases the ability of muscle to utilize fat. During aerobic exercise, fat serves as the preferred fuel source for muscle activity; however, increasing the dietary intake of fat does not necessarily enhance this relationship.  Fat intake for athletes, as well as healthy adults, should comprise less than 30% of total calories. Fats in the diet may be of animal or vegetable origin. Selecting lean meats, nonfat or low fat dairy products and limiting added fats such as butter, margarine, salad dressing, cream sauces, gravies and fried foods will help you achieve this goal.


There is a general misunderstanding about the protein needs of athletes. Many believe that large quantities of protein foods are necessary to enhance muscle growth. Amino acid supplementation is not necessary even for body builders. Training techniques and genetics are the critical determinants of muscle size. Extra protein in the diet (in the form of food or amino acid pills) beyond what your body demands for rebuilding and repair doesn’t go to make extra muscle. Protein can’t be stored for later use, if the athletes body gets more protein than it needs, extra is broken down and stored as fat or used as energy.   High protein intakes have never been shown to be uniquely beneficial to athletes.   Intakes of protein > 15% of total calories cannot be justified on a scientific basis. For an individual consuming 4000 calories per day, 15% of calories represent 150 grams of protein or 2 grams/kg body weight for 70-kg male (note RDA is 0.8 grams/kg of body weight/day). This almost exceeds the requirement by 270%.  Protein is the toughest nutrient to digest. Your body expends a lot of energy just breaking down high protein foods. Therefore high protein foods should be avoided before training.  Protein can be supplied from animal food sources, such as lean meat, poultry, fish, eggs, milk, and cheese, or vegetable food sources such as dried beans and peas, peanut butter, nuts, seeds, and tofu.   Breads, cereals and vegetables contribute small amounts of protein in the diet. Plant protein from vegetable sources is usually low in one or more of the nine essential amino acids. Vegetable protein sources, in combination, can complement one another to provide a high-quality protein.

Japanese researchers demonstrated that "sports anemia" might appear in the early stages of training with intakes of less than 1 gram/kg of body weight per day of high quality protein.   Sports anemia is low blood levels that will decrease your ability to exercise and cause you to fill tired.  Don’t be afraid to eat meat particularly lean red meat.


To calculate your protein needs, divide your weight in pounds by 2.2 pounds to obtain your weight in kilograms.

Then multiply kilograms by the 1.8 grams of protein.  This will give your recommend grams of protein.   It is probably best to eat your protein at night after practice with some at lunch so that your body will have it available during your repair at night.


Of all the physiological factors that can cause early fatigue during exercise, dehydration is arguably the most important. Dehydration is a common occurrence, even during exercise in the cold. Dehydration decreases performance, impairs heart function that can slow physical performance, and pose serious health problems.

Athletes can lose a large amount of fluid when exercising. An athlete can become dehydrated in as little as 30 minutes.  Dehydration occurs when fluid (sweat) loss exceeds 1% of body weight (600 ml in the case of an 60-kg (135lbs) male). Work capacity and temperature control can be impaired with a loss of as little as 2% of body weight and can cause a 5-10% drop in performance. A 1/10th-temperature change can decrease performance.

During any form of exercise, working muscles produces heat, and body temperature rises. Getting rid of this heat requires fluid evaporation from the skin (sweating) which cools the body. When fluid evaporates from the skin the body therefore losses valuable water (as high as 1-2 quarts/hour) during heavy exercise. When the athlete fails to ingest enough fluid and dehydration becomes sufficiently severe, sweating decreases in an attempt to conserve body water. As a result, blood thickens, heart rate increases and body temperature rises and you get fatigue, headache, nausea, chills, stomach discomfort and increasing the chance of heat cramps, exhaustion, or stroke.

It is always the athlete’s best interest to prevent unnecessary increases in core temp that will ultimately lead to premature fatigue.  Most active people have experienced dehydration and probably haven’t been aware of it. Exercise blunts the thirst mechanism and cannot rely on thirst as an indicator of dehydration. Providing adequate fluid intake before, during and after exercise can prevent dehydration. Fluid replacement practices should be designed to match fluid intake and sweat loss. This approach will require sports competitors to ingest more fluid, often more that they are accustomed to drinking.

Plain, cool water (5° to 10°C; 40° to 50°F) is an effective fluid replacement, and it is the most readily available and least costly alternative. Drink plain water before or during activities lasting 60 minutes or less.

Electrolytes (sodium, potassium, chloride, and magnesium) are lost in sweat, but the loss of water is considerably greater. However, in sport or training that requires more than 1 hour of continuous effort, a carbohydrate-electrolyte solution should be provided to improve performance.

Nutritional factors can conceivably influence performance at almost any stage during training or competition.

Table 2: Recommendations for hydration.

Day before

Drink fluids frequently

Pre-event meal

2-3 cups water

2 hours before

2-2 1/2 cups water

1/2 hour before

2 cups water

Every 10-15 minutes during the event

1/2 cup cool (45-55 degrees) water

After event

2 cups fluid for each pound of weight you lost

Next day

Drink fluids frequently (it may take 36 hours to rehydrate completely).

The ultimate competitive ability of an individual is in part, related to his or her capacity to train maximally. Consequently, every effort must be made to ensure all nutritional needs are met during this period.  When carbohydrate and fluids are deficient in the diet it leads to fatigued muscles, weakness and tired feeling that leads to decrease in performance. The following explains why this happens and why the High Performance Diet is important to follow.


The goals of the pre-exercise meal:

Prevent low blood sugar and associated symptoms (light-headedness, blurred vision, fatigue, and indecisiveness)

Prevent feelings of hunger

Provide energy for working muscles

The pre-exercise meal is important, especially before morning exercise. The body has to draw on the liver’s supply of glycogen for energy. This supply eventually runs low if you skip breakfast and blood sugar decreases, giving you a hungry, tired feeling. The lowering of fuel supply to the brain can also have a negative effect on your mental power that can further hinder performance. Consuming a meal, or at least a light snack, before exercise helps to replenish liver glycogen and helps to maintain normal blood sugar levels and endurance. Complex carbohydrates are ideal because they are quickly digested and absorbed into the bloodstream, leaving the stomach quickly so there is less chance of indigestion and nausea during the event. Research has demonstrated that food ingested 3-4 hours prior to exercise is used for energy during exercise. However, you must realize that you can’t rely on that day’s meal alone.  Your dietary intake of 2-3 days preceding the exercise can affect performance.

The pre-exercise meal should be low in fat. Try to avoid fat 12 hours before exercise because fat leaves the stomach slowly and may cause a bloated, heavy feeling. Try to avoid high protein foods right before exercise because proteins require more energy to digest and also cause an increase in urine output promoting the loss of needed fluid. You also need to avoid high fiber and gas-forming foods; these foods can cause stomach discomfort during the exercise. High fiber foods are excellent choices for general nutrition, but are not recommended for the pre-exercise meal.

You should always start exercise in a fully hydrated state.  You should be drinking about 8 to 10 cups of water during the day.  Then prior to practice drink at least 8 to 16 ounces of fluid 2 hours before exercise and 8-20 ounces water approximately 15 minutes before exercise. Avoid starting a workout thirsty. Liquids should be cool for faster absorption. You also need to make a special effort to drink more water in higher altitudes and warmer temperatures.


Goals for nourishment during exercise:

Replace both muscle glycogen and fluid losses

Maintain normal blood sugar levels

Provide source of energy for the exercising muscles

Replenishing carbohydrate and fluid throughout exercise that lasts over an hour can postpone fatigue and prolong peak performance and ensure greater stamina by keeping muscle glycogen stores filled.

Scientific studies shows that after one-hour of continuous exercise, athletes are likely to tire due to carbohydrate depletion. Research data also suggests that fatigue can be delayed by as much as 30-60 minutes by eating carbohydrates during exercise: 30 to 60 grams of carbohydrate/hour (120-140 calories) appears to be an optimal range of carbohydrate intake for maintaining or improving performance. Ingesting greater quantities of carbohydrate does not further improve endurance and may, in fact, hinder performance. During exercise of moderate intensity, blood flow to the stomach is 60% to 70% of normal, so the athlete can still digest food. Depending on the sport, the food can be provided as a solid food or a liquid (Sport Drink). Since liquid foods leave the stomach faster than solid foods, the athlete may want to experiment with liquid meals to determine if they offer any advantage. You should keep in mind anecdotal reports that too much liquid may "slosh" in the stomach and contribute to nausea. Therefore, any new meal should be experimented with during training to determine its level of acceptance.

In addition to replacing carbohydrates, the athlete should be careful to replace fluids lost through sweat. Carbohydrate-containing fluids, such as sports beverages, replace both muscle glycogen and water losses; they are the best choice for both good nutrition and top performance. Sports drinks containing between 14-19 grams of carbohydrates (6-8% carbohydrates) and 50-80 calories per 8-ounce serving are appropriate before or during activities lasting longer than 60 minutes. The carbohydrates and electrolytes can help increase the rate of fluid absorption from the gastrointestinal tract.  Sweating is generally less during swimming than during running because of the enhanced cooling effect provided by the water.


Goals for after exercise nourishment:

Replenish carbohydrate (glycogen) stores to maintain exercise performance on a day-to-day basis.

Replace fluid that has been lost during exercise.

If you want to be ready for the next day’s workout, you must replenish your carbohydrate reserves so that subsequent exercise performance is not impaired.

After the carbohydrate supply has been depleted, it takes 24-48 hours for full recovery. Muscles are most receptive to replacing muscle glycogen within the first 2 hours after a hard workout. Research shows that full recovery can be achieved if carbohydrate intake (40-60 grams) begins immediately after exercise or within the first 30 minutes after exercise, and to continue at 2-hour intervals up to 4 hours.  This may be a good time for a power bar on the ride back/to Aiken.  This is especially important if you are working out twice a day. Failure to consume carbohydrates at this time may hinder optimal glycogen recovery and endurance.

Not only the timing of carbohydrate intake but type of carbohydrate consumed can affect the rate of glycogen synthesis. Glucose appears to refuel the muscles better than fructose (sugar in fruits, juices, and sodas). Research shows that athletes who consume glucose after exercise have a 50% faster rate of glycogen repletion than those who consume fructose.

Fluid replacement should be at least 8 to 16 oz of fluid after exercise, or 1 pint (2 cups) per every pound of body weight lost. Only athletes who exercise for more than an hour daily with heavy fluid losses from sweat are at risk for depleting sodium and potassium. Most can replace these electrolytes with the fluids and food they consume after exercise. For those who report that exercise "kills the appetite," sport beverages can provide adequate carbohydrates and also supply needed fluids. Sport beverages can also be helpful after exercise when an athlete is unlikely to make appropriate selections, or when the right foods are unavailable.   However, DO NOT forget your protein intact at lunch and after practice.


EAT to Improve Performance

Optimal nutrition is attained with sound dietary practices that are applied on a continuing basis, not just a few hours before or during competition. Nutritional factors can conceivably influence performance at almost any stage during training or competition.

Performance Diet Guidelines

Energy intake that maintains desirable body weight

6-10 grams of carbohydrate per kilogram body weight/day (about 60-70% of total calories)

6 grams/kilogram body weight for one hour of training per day

8 grams/kilogram body weight for two hours of training per day

At least 10 grams/kilogram body weight for three hours of training per day

10-15% protein or 1.5-2.0 grams/kilogram body weight/day

20-30% fat

Plenty of fluids to prevent dehydration

Sufficient amounts of vitamins and minerals.  Recommend taking a multivitamin twice per day.



The International Olympic Committee and United States Olympic Committee has put large doses of caffeine on the banned list. However, small amounts of caffeine have been shown to increase performance of endurance athletes.  However, the use of caffeine should be weighed against its negative effects.  Caffeine can make you nervous, it can upset your stomach, and cause you to urine more leading to dehydration.  In general, small amounts of caffeine can safely be consumed. This would be 1-2 cups of coffee, 3 cups of tea, or 1 Mountain Dew. I would recommend avoiding carbonated beverages particularly on competition days.  Caffeine or its equivalent occurs in coffee, iced tea, and chocolate.  Never try caffeine intake for the first time before a competition. The physiological effects of caffeine vary among individuals and are dependent on dosage and frequency of intake, body composition, overall anxiety level, and past usage habits. 


Becoming an elite athlete requires good genes (thank your parents), good training and conditioning (listen to your coaches), and a sensible diet (this one is your responsibility). Optimal nutrition is essential for peak performance.







Sample menu of a high carbohydrate diet.  This would be used for only 3 days prior to a major competition with multiple events or single event such as 800 meter or longer.

Food item




8 ounces orange juice



1 cup oatmeal



1 medium banana



8 ounces low-fat milk



1 slice whole wheat toast



1 tablespoon jelly




2-ounce slice ham



1 ounce Swiss cheese



2 slices whole wheat bread



1 leaf lettuce



1 slice tomato



8 ounces apple juice



8 ounces skim milk



2 cookies




3 cups spaghetti with meat



1 cup tomato sauce
with mushrooms



2 tablespoons Parmesan cheese



4 slices French bread



1 slice angel food cake



1/4 cup sliced strawberries



1/2 cup ice cream




16 ounces grape juice



6 fig cookies






(75% of total calories)

Eating sugar (i.e. candy) 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. 


Two pre-event meal plans.

Pre-Event Meal Plan I
(approximately 500 calories)

Milk, skim

1 cup

Lean meat or equivalent

2 ounces


1 serving (1/2 cup)

Bread or substitute

2 servings

Fat spread

1 teaspoon

Pre-Event Meal Plan II
(approximately 900 calories)

Milk, skim

2 cups

Cooked lean meat or equivalent

2 ounces


1 serving (1/2 cup)

Pasta or baked potato

1 cup or 1 medium

Bread or substitute

2 servings


1 serving (1/2 cup)

Fat spread

1 teaspoon

Dessert: Angel food cake or plain cookies

1 piece 2 cookies


Amino Acids (the building block of proteins)

Dietary protein provides 20 essential and nonessential amino acids:

Essential amino acids are Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine.

Nonessential amino acids are Alanine, Arginine, Asparagine, Aspartic acid, Cysteine, Glutamic acid,Glutamine, Glycine, Proline, SerineTyrosine

The effects of amino acid supplementation on endurance performance in humans are somewhat equivocal but generally suggest that it is not helpful.


To maximize their potential, athletes engage in cyclic periods of high-intensity overload training, often referred to as "overreaching" or "short-term overtraining." A cycle of overreaching is followed by a cycle of tapering or recovery, normally leading to supercompensation and improved performance. In contrast, if performance incompetence persists despite an appropriate regeneration period and an organic disease has been excluded, overtraining syndrome may be present. The overtraining syndrome seems to affect mainly endurance athletes.  The overtraining syndrome is defined as a state of prolonged fatigue and underperformance caused by a failure to recover from intense training and competition. Symptoms, which must last at least 2 weeks despite adequate rest and no other identifiable medical cause, include fatigue, heavy muscles, depression, sleep disturbances, irritability, increased anxiety, altered mood state, suppressed reproductive function, loss of appetite with weight loss, upper respiratory tract infection, loss of competitive drive, and persistent performance incompetence.   This is why daily sleep and proper nutrition is SO IMPORTANT.  This is an avoidable condition.  Due your part and listen to your coaches instructions on level of exertion during training.  A tremendous amount of thought and planning goes into developing your training and tapering schedule.  However, the athlete (you) must still execute the plan and come nourished, rested, and mentally prepared for training on a daily basis.  You cannot control your genes but you can control your effort and dedication along with your diet and rest.





Creatine loading, most commonly achieved by supplementing with approximately 20 to 30 g creatine monohydrate daily for 5 to 7 days, has been shown to increase muscle concentrations of total creatine, including free creatine and phosphocreatine. Research strongly suggests that the increased muscular stores of free creatine and phosphocreatine are associated with enhanced performance, particularly in repetitive, very high-intensity resistance exercise and cycle ergometer exercise tasks with short recovery periods.   I could find no specific studies on swimmers.  I would save my money.


There is no legal supplement that can substantially alter performance.  Research is lending useful and helpful information about the many new products continually appearing on the market.  In addition, supplements in and of themselves should not be viewed as the sole answer to performance improvement. There is some promise to an extremely small number of supplements that appear to enhance performance, however they only do this in the realm of complete athletic training, including hard work, sports-specific training and strength training, psychological preparedness, and good nutritional intake. 


The bottom line:



Healthy Diet

Hard Work


Good coaching

Optimizing Your Chance for Competitive Success

Maintaining Health

Maximizing workout benefit

Facilitating Recovery

Competition enhancement


Maintaining Health


     Your baseline sedentary fluid requirement is 2.4 liters.  Fluids do not include caffeine containing beverages or tea.  With aerobic activity additional sweat rates of 1.5 liters/hour can occur.  Body water deficits as low as 2% have been shown to decrease aerobic capacity and work capacity.  This means a 10 to 30% reduction in the time to fatigue.  In rowers, times increased by 8% when athletes were 3% dehydrated.  The water deficit causes an increased use of your muscle glycogen.  You built up more lactic acid but have a harder time eliminated it.  To top it off, mental performance and concentration is also affected. 


Drink 2.4 liters through the course of the day. 

Drink 400-600 ml of water or Gatorade 2 hours before exercise

If exercising greater than 1 hour you should drink 120 to 200 ml every half hour.  This should be a drink containing no more than 6% glucose or water.

Note: Over hydration can be dangerous.

Fluids During Exercise

If exercising greater than 90 minutes, intake of a 6% carbohydrate solution has been shown to prolong performance of athletic activity over use of water alone.

Fluids During Recovery 

Should be done in conjunction with meals.  If following the above no appreciable deficit should be present.



   Sleep deprivation can cause both acute and chronic decline in mental and athletic performance.  In general, 8 hour of sleep per day in a teenager is recommended for optimal health.   Chronic sleep deprivation can also lower your immune system making illness more likely.  During sleep the body repair processes occur.  It is during the hours of sleep that the secretion of several hormones is increased to include growth hormone.  Chronic sleep deprivation has been shown to result in increase in muscle aches and pains. 

     The amount of sleep that you get the 3 days prior to competition is critical.  You cannot catch up on sleep with one good nights rest. 



     In general a healthy diet should be consumed.  There is great disagreement of what a healthy diet is.   In the athletes, fats should account for 20 to 25 percent of calories.  Diets with less that 15% of calories from fat no NOT offer a performance benefit.  Fruit and vegetable should be a mainstay of the diet with at least 3 serving per day of each.  The amount of calories from protein needs to be somewhat higher in the athlete.  Meat protein may be particularly important as mild iron deficiency is often found in swimmers (particularly females). This iron deficiency comes from poor intake, increased breakdown of blood vessels, and fluid changes in the athlete.  Protein intake should be about 1.4 to 1.7 grams per kilogram of body weight per day.  Intake above 2.0 grams per kilogram per day does not provide added benefit. 

    Prior to exertion (2hr to 3hr), consumption of a small carbohydrate meal (100 to 200 grams of carbohydrates) is recommended.  Increased the time to fatigue compared to starting exercise with a 2 to 3 hour fast.  Solid or liquid form did not matter as long as the fluid volume was the same.

    During exercise the intake of sucrose and glucose improved performance but the intake of fructose did not.  Fructose also caused increased gastrointestinal symptoms.


Vitamins and others

     Although best consumed from a healthy diet consisting of raw vegetables, fruits, and meat, it is clear that not all teenagers eat healthy.  A study of collegiate endurance athletes including swimmers showed low levels of vitamins (B6, B12, Vitamin C, and E).  Also noted to be low was iron, magnesium, and calcium.

     Supplementation of 200 miu of Vitamin E per day is recommended.  Prevention of oxidative damage of tissue from prolonged exercise.

     Iron supplementation has been shown to improve endurance in iron-depleted women even if their blood count is normal (no anemia).  Supplement 100mg Ferrous sulfate per day.  Generally 3 month of repletion will be needed.  Absorption of iron is enhanced by

Vitamin C.

     Calcium intake is recommended at 1200 to 1500 mg per day total (2 doses).



Eat healthy

Take at least a good multivitamin per day

Consider 1 extra strength Tums twice a day.  Get the flavored kind.

Consider Vitamin E and C (500mg bid) supplementation

Females discuss iron with your doctor


Protein Calculation

Weight kilograms          Weight Pounds             Daily Protein grams                   Daily Protein ounces

30                                                                66                                                  60                                            2.0

40                                                          88                                                  80                                            2.8

50                              110                                                100                                            3.5

60                              132                                                120                                            4.2

70                              154                                                140                                            5.0

80                              176                                                160                                            5.7

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