nutrition and athletic performanceAlternative Names
Good nutrition should be a part of every athlete's training program. Those who enjoy sports for fun or competition need good nutrition. The body needs kilojoules and nutrients to run a race or to take a walk.
Generally, sports can be divided into 2 categories. Those categories are short duration/high intensity, as in sprinting or weight lifting, and long duration/lower intensity, as in sustained running or jogging. In reality, most sports alternate between the two.
Kilojoules, protein and water should be important to athletes. Minerals, electrolytes and antioxidants (substances that fight the effects of free radicals which can damage the body) are important, too.
Kilojoules from carbohydrates are the quickest source of body fuel. Carbohydrates are easily broken down to sugar, or glucose. Glucose circulates in blood and is taken up by cells that need energy. For active people, a steady intake of carbohydrates fuels the muscle cells. Carbohydrates also fuel the heart, nerves and brain cells. The ideal training diet supplies 55-60% of kilojoules from carbohydrate.
Glucose can be stored in the muscles and liver. This form of glucose is called glycogen (glie-kah-jen). When blood sugar levels start to fall, glycogen is changed to glucose, raising blood glucose levels. Well trained athletes who eat a high-carbohydrate diet can improve glycogen stores. This means more fuel for longer workouts. Commonly called "carbohydrate loading," this type of diet works by building glycogen stores.
Before a strenuous event, a high carbohydrate meal such as pasta, potatoes, rice, cereal or fruit is recommended. Sauce on the pasta or toppings on potato is okay. Between 70% to 80% of the kilojoules for the meal should come from carbohydrates.
It is important to follow strenuous workouts with a snack or meal of 100 to 200 grams of carbohydrate to replace glycogen. For example, banana and honey sandwich with 1 cup fruit juice add up to 100 grams of carbohydrate. In general, endurance athletes should build a diet based high in carbohydrates and include grains, breads, starchy vegetables, fruits, and milk. Additional carbohydrate, such as sports drinks, sugar or lollies may be needed.
People involved in short-duration, high-intensity activities need carbohydrates, too. People in these sports, like weight lifting, tend to focus on protein. Protein is important to muscle growth, but carbohydrates fuel the body. Carbohydrates should be the majority of kilojoules eaten, between 55% to 60%.
Some athletes want to build muscle mass. Protein intake should be between 1.2 to 2 grams per kilogram of body weight. For example, a 70-kilogram person can eat 70 to 114 grams of protein per day. Eating too much protein taxes the kidneys. People who eat a lot of protein should also drink a lot of water.
Water is probably the most important nutrient for an athlete's good health. In addition to the recommended 8 glasses a day, athletes should drink 1 to 2 cups prior to working out or competing. Endurance athletes are encouraged to drink 150ml every 15 to 20 minutes during training or competition. Water or sports beverages are acceptable. Caffeinated drinks or alcohol are not. Caffeine and alcohol are both diuretics. They can lead to dehydration (loss of body fluid). After sport, drink as much water as you can get in to rehydrate your body, for at least a couple of hours.
Sports beverages are a good source of the electrolyte minerals potassium, sodium and chloride. These are important for endurance athletes and those who sweat a lot. However, simply eating a balanced diet will also provide plenty of electrolytes for most leisure athletes. Sports drinks are acidic and may cause erosion of your tooth enamel.
Iron is an important mineral for athletes. It helps carry oxygen in the blood. Female and/or vegetarian athletes should have their iron levels checked to screen for iron deficiency anaemia.
Exercise causes oxidative stress, a type of stress caused by exposure to oxygen. Athletes may have a higher need for antioxidant nutrients. Athletes should make sure they get the recommended daily intake for vitamins A, C , E and the mineral selenium.
Author: Clare Armstrong, MS, RD
Reviewer: eknowhow Medical Review Panel
Editor: Dr John Hearne
Last Updated: 16/10/2004
Potential conflict of interest information for reviewers available on request