There are three primary factors that influence your athletic performance: genetics, training and nutrition. You can't do anything about your heredity, but you do have control over your training and food choices.
Many athletes who train hard to excel are defeated by their diets instead of their competitors. Though a balanced diet won't guarantee you athletic success, an unbalanced diet may undermine your training.
Some athletes will try any dietary regimen in an effort to improve performance, stay healthy, or lose weight. The desire for that elusive "secret ingredient" can cause them to disregard sound nutrition practices and become victims of nutrition fraud. Most popular diets and supplements don't give athletes the results they want, and some dietary fads are actually harmful.
Choosing the proper food is as important to your athletic success as having the most appropriate correct training program. There are sound dietary strategies that you can use to perform closer to your potential. The Ultimate Sports Nutrition Handbook provides the most current information on nutrition for peak athletic performance. It presents sensible nutrition advice that you can put into practice immediately.
Food fulfills three basic needs:
These three requirements are met by components of foods called nutrients. There are six classes of nutrients, and each class has special chemical characteristics suited to meet the specific needs of the body. The six classes are carbohydrates, fats, proteins, vitamins, minerals and water.
Carbohydrates, such as sugar and starch, are the most readily available source of food energy. During digestion and metabolism, all carbohydrates are eventually broken down to the simple sugar glucose for use as the body's principal energy source. Glucose is stored in the muscles and liver as a substance called glycogen, which is actually a long chain of glucose molecules hooked together. A high-carbohydrate diet is necessary to maintain muscle glycogen -- the primary fuel for most sports.
Sugar and starch are grouped together as carbohydrates because they have a chemical similarity. All carbohydrates are made up of one or more simple sugars, the three most common being glucose, fructose and galactose. The simple sugar glucose connected to fructose forms sucrose, or table sugar. When more than two glucose molecules are connected, they become a starch, or complex carbohydrate. Starches contain anywhere from 300 to 1,000 or more glucose units hooked together.
Though our bodies use both the sugars and the starches for energy, a high-performance diet emphasizes complex carbohydrates. Foods high in complex carbohydrates, such as bread, cereal, rice, beans, pasta and vegetables also supply other nutrients, such as vitamins, minerals, protein and fiber. Sweet foods that are high in sugar (i.e., candy bars, donuts and cookies) supply carbohydrate, but they also contain a high amount of fat and only insignificant amounts of vitamins and minerals.
Fruit contains the sweetest of all simple sugars -- fructose. Because fruit is mostly water, its sugar and calorie content is relatively low. Like starchy foods, most fruits are rich in nutrients and virtually fat free.
Fats, or lipids, are the most concentrated source of food energy. One gram of fat supplies about nine calories, compared to the four calories per gram supplied by carbohydrates and protein. Fat is the body's only source of a fatty acid called linoleic acid that is essential for growth and healthy skin and hair. Fat insulates and protects the body's organs against trauma and exposure to cold. Fats are also involved in the absorption and transport of the fat-soluble vitamins.
Fats are the source of fatty acids, which are divided into two categories: saturated and unsaturated (including polyunsaturated and monounsaturated fatty acids). These fatty acids differ from each other chemically based on the nature of the bond between carbon and hydrogen atoms.
As a general rule, saturated fat (i.e., butter and lard) is solid at room temperature and is derived mainly from animal sources. Unsaturated fat (i.e., safflower, canola and corn oil) is liquid at room temperature and is found mainly in plant sources. Palm and coconut oils are exceptions -- they are highly saturated vegetable fats. Saturated fat should be restricted because it raises blood cholesterol, which in turn increases the risk of heart disease.
Protein is a major structural component of all body tissues and is required for all tissue growth and repair. Proteins are necessary components of hormones, enzymes and blood plasma transport systems. Protein is not a significant energy source during rest or exercise. However, the body will use protein for energy if you're not eating enough calories or carbohydrates (i.e., starvation diets and fasting).
The proteins in both animal and plant foods are composed of structural units called amino acids. Of the more than 20 amino acids that have been identified, nine must be provided by our diet and are called essential amino acids, as shown in Table 1-1. Meat, fish, dairy products, eggs and poultry contain all nine essential amino acids and are called complete proteins. Vegetable proteins, such as beans and grains, are called incomplete proteins because they do not supply all the essential amino acids.
Table 1-1
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Isoleucine |
Methionine |
Trypthophan |
Leucine |
Phenylalanine |
Valine |
Lysine |
Threonine |
Histidine |
The body can make complete proteins if a variety of plant food -- beans, grains, vegetables, fruits, nuts and seeds -- and sufficient calories are eaten during the day. Vegetarians need not worry about combining specific foods within a meal, as the old "complementary protein" theory advised. Well-balanced vegetarian diets may even decrease the risk of heart disease and cancer, because they are lower in fat and higher in complex carbohydrates than the average american diet.
Vitamins are organic molecules (they contain carbon) that the body cannot manufacture but which it requires in small amounts. Contrary to what many athletes believe, vitamins do not provide energy. They are metabolic regulators that help govern the process of energy production, growth, maintenance and repair. Thirteen vitamins have been identified; each has a specific function in the body and also works in complicated ways with other nutrients. The function and sources of most of the vitamins are shown in Table 1-2.
Vitamins are divided into two groups: water soluble and fat soluble. Fat-soluble vitamins include A, D, E and K. They are not excreted but instead are stored in body fat, principally in the liver. Taking a greater amount of vitamins A and D than the body needs over a period of time can produce serious toxic effects. Too much vitamin A can cause loss of appetite, headaches, irritability, liver damage, bone pain and neurological problems, including brain damage. Too much vitamin D can cause weight loss, vomiting, irritability and destructive deposits of excess calcium in soft tissues (like the kidneys and lungs), and potentially fatal kidney failure.
While vitamin A is found only in animals, dark orange-yellow and green leafy plants contain substances called carotenes (i.e., betacarotene) that our bodies can convert to vitamin A. Unlike vitamin A, carotene is fairly safe when consumed in large amounts. The body stores excesses of carotenes (which can make the skin look yellow-orange) rather than converting them to vitamin A.
Vitamin C and the B complex are soluble in water and must be replaced on a regular basis. When you consume more water-soluble vitamins than you need, the excess is eliminated in the urine. Though this increases the vitamin content of your urine, it doesn't help your performance. Consuming excessive amounts of water-soluble vitamins, such as Niacin and B6 can also cause dangerous side effects.
Table 1-2
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ADULT U.S. RDA
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FUNCTIONS |
SOURCES |
Vitamin C
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Collagen formation,
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Citrus fruits, tomatoes,
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Vitamin B1
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Energy production,
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Meat, whole grain cereals,
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Niacin
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Energy production,
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Peanut butter, whole grain
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Vitamin B6
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Protein metabolism,
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Whole grain cereals,
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Folacin
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New cell growth, red
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Greens, mushrooms, liver |
Vitamin B12
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Energy metabolism, red
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Animal foods |
Vitamin A
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Vision, skin,
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Milk, egg yolk, liver
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Vitamin D
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Formation of bones, aids
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Sunlight, fortified dairy
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Vitamin E
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Antioxidant, protects
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Vegetable oils,
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Vitamin K
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Blood clotting |
Greens, liver |
Minerals are inorganic compounds (they don't contain carbon) that serve a variety of functions in the body. Some minerals, such as calcium and phosphorus, are used to build bones and teeth. Others are important components of hormones, such as iodine in oxygen carrier within red blood cells. The function and sources of most of the minerals are shown in Table 1-3.
Minerals also contribute to a number of the body's regulatory functions. These include regulation of muscle contraction, conduction of nerve impulses, clotting of blood and regulation of normal heart rhythm.
Minerals are classified into two groups based on the body's need. Major minerals, such as calcium, are needed in amounts greater than 100 milligrams per day. Minor minerals or trace elements, such as iron, are required in amounts less than 100 milligrams per day. Calcium and iron are both minerals of concern for athletes, especially women.
Water is the most essential of all nutrients for athletes. An adequate supply of water is necessary for control of body temperature (especially during exercise), for energy production, and for elimination of waste products from metabolism.
Dehydration -- the loss of body water -- impairs athletic performance and increases the risk of heat illnesses (heat exhaustion and heatstroke). Water is probably the nutrient most neglected by athletes.
It's easy to overlook the benefits of water because it is so readily available and inexpensive.
Table 1-3
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ADULT U.S. RDA
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FUNCTIONS |
SOURCES |
Calcium
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Bone formation, enzyme
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Dairy products, green leafy
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Iron
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Hemoglobin formation, muscle
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Lean meat, beans, dried
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Magnesium
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Energy production, muscle
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Grains, nuts, meats, beans |
Sodium
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Nerve impulses, muscle action,
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Table salt, small amounts
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Potassium
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Fluid balance, muscle action
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Bananas, orange juice
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Zinc
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Tissue growth and healing,
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Meat, shellfish, oysters,
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Copper
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Hemoglobin formation, energy
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Whole grains, beans, nuts,
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Selenium
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Antioxidant, protects against free
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Meat, seafood, grains |
Chrominum
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Parts of glucose tolerance
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Whole grains, meat,
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Manganese
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Bone and tissue development,
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Nuts, grains, beans, tea,
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Iodine
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Regulates metabolism |
Iodized salt, seafood |
Fluoride
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Formation of bones and tooth
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Tap water, tea, coffee, rice
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Phosphorous
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Builds bones and teeth,
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Meat, fish, dairy products
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*EMR - estimated minimum requirement
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The key to improved performance and health cannot be found in any one food or supplement, but in a combination of foods that provides the nutrients you need. For peak performance, athletes need to eat a varied diet most of the time. you can't just focus on your pre-exercise meal or what you eat the day before competition.
You should be able to get all the nutrients you need by eating a wide variety of foods from the Food Guide Pyramid. Of the 40 known nutrients, 10 are considered leader nutrients. If you obtain adequate amounts of leader nutrients from the foods you eat, you probably will obtain the other 30 nutrients as well.
The ten leader nutrients are protein, carbohydrate, fat, vitamin A, vitamin C, thiamin, riboflavin, niacin, calcium and iron. The five food groups contain foods high in vitamins A and C. Meat group foods are high in protein, niacin, iron and thiamin. Foods in the milk group are good sources of calcium, riboflavin and protein.
Since no one food or food group supplies all the nutrients you need, it's important to choose a wide variety of foods from the five food groups in the Pyramid. By eating at least the minimum number of servings from each food group daily, you can be reasonably assured you're getting the nutrients you need for optimum performance.