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Fitness Science

The principles involved in human performance nutrition, also known as sports nutrition, are built upon the principles of general nutrition and fitness science with special emphasis on optimizing human performance. Optimal nutrition is an essential part of every athlete’s training program, and the information contained separately in the Textbook of Nutrition is essential to understanding the proper application of nutrition in athletics.

The primary areas of concern are:

1) consuming enough calories to support performance;
2) consuming the correct balance of macronutrients before, during and after exercise; and
3) proper hydration.

There are other concerns for certain population groups as well, such as vegetarian or vegan athletes, or female athletes – particularly those who compete in sports that focus on weight or body build, such as figure skating and gymnastics.

Nutrition before, during and after exercise has significant effects on human performance. A pre-event meal keeps the athlete from feeling hungry before and during the event, and it maintains optimal blood glucose levels for working muscles. Carbohydrate feedings just prior to exercise can help restore suboptimal liver glycogen stores, which could result, for example, after an overnight fast. Allowing for personal preferences and habits, the pre-event meal should be high in carbohydrate, low in fat and fiber and easily digested.

Hydration and nutrition during an event has revolutionized human performance. During exercise, athletes should consume 30 to 60 grams of carbohydrate each hour (120 to 240 calories from carbohydrate per hour). Since both carbohydrates and fluids are necessary during events, sports drinks can go a long way in providing adequate carbohydrates and fluids. Typical foods that are used during long events include sports drinks, carbohydrate gels, energy bars and bananas. During vigorous activity, heat that is produced is dissipated through the process of sweating. However, long-term, extensive sweating can pose significant challenges for athletes with regard to fluid and electrolyte balance. 

Without effective management, athletes will fatigue prematurely and, as dehydration progresses, heat exhaustion, heat cramps and heat stroke can result. Finally, recovery from intense activity requires nutrients that will replenish muscle glycogen stores, body water, electrolytes and triglyceride stores in skeletal muscle. Proper nutrition during the recovery period is essential for rapid and effective recovery and for optimal performance at the next event or workout.

Over the long term, athletes must pay attention to general nutrition and conditioning, while, during an event, adequate hydration and electrolytes become critical to maintaining optimum performance.



Recent studies in mice have indicated an interrelation between energy balance, diet, and the composition of the gut bacteria.
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The Fitness Textbook will teach you the basic principles of human performance nutrition, including muscle metabolism and fuel utilization before, during and after exercise.
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