To fuel high-intensity exercise, the body needs increased amounts of calories and all nutrients, particularly, increased carbohydrates fuel sources, additional protein to maintain muscle mass, and additional iron and B vitamins to support the oxygen-carrying capacity of the blood. In addition, nutritional prerequisites for a well-nourished athlete include increased antioxidant nutrients to protect the cells in a highly active, highly-oxygenated body from oxidative damage.
Exercise of all types requires energy in the form of calories. The amount of calories needed to fuel physical activity depends on several factors including your age, your gender, your level of conditioning, and the intensity and duration of the activity. For example, sports that require repetitive muscle contractions (running, rowing and swimming) use more energy than activities that require maintenance of muscle contractions (gymnastics and golf). Athletes need to consume large amounts of calories and carbohydrates to be sure they have enough fuel available to support high-intensity exercise.
Exercise causes loss of fluid through sweating and respiration. The fluid that is lost is taken from the blood, which can reduce blood volume. If fluid is not replaced during and after exercise, serious dehydration can result, causing an increase in body temperature and impairing heart function. Drinking water is probably the best way to replace fluids. However, some experts believe that it is also necessary to replace lost electrolytes. Electrolytes are minerals ' sodium, chloride, and potassium ' that are lost when we sweat. (Other minerals can be lost through sweat as well - including the antioxidant mineral, zinc). While many different 'electrolyte-replacement' sports drinks are available, you may not need to spend money on these expensive drinks to ensure adequate replacement of electrolytes. In most cases, a well-balanced diet rich in fruits and vegetables provides an appropriate amount of these important minerals.
If you exercise regularly for long periods of time or at a high level of intensity (for example, training for a marathon), you may find that you are more susceptible to infections, specifically upper respiratory tract infections. High-level physical activity does generate a significant amount of free radicals, which can tax and weaken the immune system, increasing your chance of catching a cold.
In recent years, protein and amino acid supplements have become popular among athletes. Of special interest has been glutamine, an amino acid derived from glutamic acid. Glutamine is the most abundant amino acid in muscle cells and helps provide fuel to these cells when carbohydrate reserves are low. Glutamine also helps build muscle and can help prevent breakdown of muscle, which is advantageous to athletes. Heavy exercise, injury, and infection can deplete the body's glutamine stores, so some athletes find it helpful to supplement with glutamine. Glutamine is also easily obtained in the diet and is found in nearly all foods that contain protein. Dietary Fat: As is the case with protein, no consensus exists about exactly how much dietary fat an athlete needs. Like other adults, athletes should limit fat intake to no more than 30% of total calories and should include at least 4 grams of omega 3 fatty acids in their daily diet. It is important for athletes to remember that dietary fat slows digestion, so the best pre-event meals contain mostly carbohydrates and little or no dietary fat. B vitamins: B vitamins are important for energy production, red blood cell production, immune function, and synthesis of messaging molecules in the nerve cells. These vitamins are depleted rapidly any time the body is exposed to internal or external stress. For all of the above reasons, B vitamins are critical to a training athlete. In most cases, at least twice the RDA level would be needed by a a training athlete. Iron: As a component of the myoglobin, the oxygen-carrying compound found in muscles, iron plays a crucial role in delivering oxygen to muscle cells. As a result, athletes should be sure to obtain at least the Recommended Dietary Allowance of iron each day, 8 mg for men and 18 mg for women. Antioxidant nutrients: Athletes should ensure a high intake of the antioxidant nutrients, vitamin C, vitamin E, and carotenoids, to help the body deal with the free radicals that are produced as a consequence of high-intensity exercise. Some research points specifically to the benefits of vitamin C in preventing post-exercise infections. In addition, vitamin C may help reduce cortisol levels. Cortisol is a hormone that can increase breakdown of muscle components, and cortisol levels are often elevated after exercise. Double the RDA intake level for these antioxidant nutrients would be the minimal recommended starting point for many training athletes.
For optimal performance, meals should be eaten 3-4 hours before an athletic event or training session. Consequently, athletes who train for several hours a day sometimes find it difficult to time meals and snacks around their exercise routine, and because their calorie needs are so high, these athletes have difficulty obtaining enough nutrients.
Unfortunately, a significant number of competitive athletes have eating disorders such as anorexia nervosa and bulimia, which impacts the quantity and type of food eaten. For example, some athletes severely restrict calories and fat to prevent weight gain or to lose body fat, a dangerous and (in the long run) counterproducive behavior.
The World's Healthiest Foods offers athletes the means of accessing the information and developing the skills needed to choose and prepare food that will enable them to maximize their performance, while maintaining their health. The World's Healthiest Foods provide maximum nutrition, improving metabolism, energy, and the ability to gain muscle, while lessening cellular damage and recovery time. With the personalized information available on the World's Healthiest Foods website (Food Advisor), you can quickly determine which foods will best support your training goals. Then take advantage of the exceptional recipes specially developed to fit your needs. All recipes take a half hour or less to prepare, and each provides not only simple instructions, but video clips demonstrating the procedures involved. With the World's Healthiest Foods, you can quickly supply your body with the nutrition needed for optimal performance.