Aside from training, nutrition is the most important influence on sports performance. To reach one's highest potential, all of the body's systems
must be working optimally. The best way to achieve this is to eat a variety of nutritious foods. Calories, carbohydrate, protein, fat, vitamins, minerals, and fluids all play a unique and crucial role.
To have enough energy for exercise (and for life), an adequate number of calories must be consumed. The amount of calories needed depends on many different factors, such as age, sex, height, weight, muscle mass, and fat mass. Too few calories can negatively affect workouts and energy levels, as well as cause the breakdown of muscle and bone, increasing the risk of injury.
It is important to nourish the body after several hours with no food (such as during sleep), so breakfast is an important part of adequate calorie intake. Choosing high-nutrient foods—such as fortified cereals with milk, peanut butter with whole grain bread, yogurt, cheese, or fruit—gives the body the right fuel to start the day. Nutritious meals and snacks can also help the body stays fueled throughout the day.
Carbohydrates are the body's main energy source for all types of exercise. Carbohydrate is stored as glycogen in the body, and the amount of glycogen stored in the body affects stamina and endurance. When muscle cells run out of glycogen, fatigue sets in and performance will suffer, though the effects will vary among different sports. Training and eating properly, with particular attention to carbohydrates, can increase and maintain glycogen stores, which is particularly important for endurance athletes.
A large part of an athlete's diet should be carbohydrate. Foods high in carbohydrate include pasta, rice, cereals, starchy vegetables (e.g., potatoes, carrots, corn, sweet potatoes), fruit, and bread. Not all carbohydrates are equal in providing needed nutrients, however. Focusing on carbohydrate from whole grains, fruits, and vegetables will make sure vitamins, minerals, fiber, and other important nutrients are part of one's diet, while filling up on too many sweets and processed foods can negatively impact sports performance.
Kim Schenck, The Gale Group Inc., Macmillan Reference USA, New York,