Marathoning Start to Finish

Food and Performance

As you discovered in the physiology section, the source of energy for running is breakdown of the food you eat. Proper intake of food or good nutrition is important for you to gain the benefits of training. A look at general nutrition for the athlete will follow along with some specifics on the relationships of the nutrients to athletic performance.

Human nutrition is thought to require six general classes of nutrients. These are carbohydrates, fats, protein, vitamins, minerals and water. These nutrients are essential for human life and inadequate intake may result in disturbed body metabolism, disease or death. Not all necessary nutrients are contained in any one food and an intake of what is called "a balanced diet", is necessary to achieve adequate nutrition.

Food has three major functions. The first is to provide energy for human metabolism. Carbohydrates and fats are the prime sources of energy. Protein can also provide energy, but that is not its major function. Second, food is used to build and repair body tissues. Protein is the major building material for muscles and other soft tissues while minerals such as calcium and phosphorus are used to build and repair bony tissue. Regulation of body processes is the third use of food. Vitamins, minerals and proteins work together to perform this function. These three functions become increasingly more important to the physically active person. Metabolic activities may increase by tenfold for periods of an hour or longer. Physical performance may be hampered seriously by inadequate nutrition. However, studies on supplemental feeding beyond adequate intake have not revealed an increased capacity for physical performance. The key is to be certain that you are receiving optimal amounts of each specific nutrient recommended by current knowledge of the requirements. Proper nutrition is necessary to optimize energy sources, build and repair tissues, and regulate body processes especially during and following exercise periods.

The four food groups can be a useful guide in taking in the key nutrients. Foods are grouped by similar nutrient values into the Meat Group, the Milk group, the Bread-Cereal Group or the Fruit-Vegetable Group. Eating a wide variety of foods throughout the four food groups helps you to receive an adequate supply of nutrients through a balanced diet. The table below shows the food groups and the recommended minimum servings for adults.

    Meat Group  :  Milk Group  :  Fruit-Vegetable  : Bread-Cereal
    
        2              2                 4                4

This approach may have some problems and not be the total solution to a balanced diet. The trend of the American public towards consumption of fats, simple sugars and alcohol led to a Subcommittee of the US Senate to recommend dietary goals for the American public. They are shown on the table below.

                      Typical US Diet       Proposed Diet
Goals
    Fat                     42%                     30%
 	Saturated              16%                     10%
	Monounsaturated        13%                     10%
        Polyunsaturated        13%                     10%

    Carbohydrate            46%                      58%
        Simple                 24%                      10%
        Complex                22%                      48%

    Protein                 12%                      12%

    Cholesterol          500 - 1000 mg               300 mg

    Salt                   6 - 18 g                  3 g

The Human Nutrition Center of the USDA makes the following simple recommendations to help you meet the dietary goals.

Eat a wide variety of foods from the Basic 4 Food Groups.
Avoid excessive fat, saturated fat and cholesterol.
Avoid excessive sodium and salt.
Avoid excessive amounts of sugar.
Drink alcohol in moderation.
Eat foods high in starch and fiber.
Maintain your ideal body weight.

A good diet is not something you go on, it is simply he way you always eat. The athlete engaged in heavy training should not attempt a weight reduction diet, but may need to change dietary habits to healthy ones. For a more complete treatment at general nutrition, we recommend Jane Brody's Nutrition Book. If you are more interested in applications of nutrition to exercise and performance, choose Williams' Nutrition for Fitness and Sport or Coleman's Eating For Endurance.