By studying this chapter, you should be able to do the following:
Describe the effect of various carbohydrate diets on muscle glycogen and on endurance performance during heavy exercise.
Contrast the “classic” method of achieving a supercompensation of the muscle glycogen stores with the “modified” method.
Describe some potential problems when glucose is ingested immediately prior to exercise and how these problems can be avoided.
Describe the importance of blood glucose as a fuel in prolonged exercise and the role of carbohydrate supplementation during the performance.
Explain why multiple carbohydrates have to be consumed during prolonged exercise when blood glucose is used at a very high rate.
Describe the need for protein during the adaptation to a new, more strenuous exercise level with the protein need when the adaptation is complete.
Describe the recommended range of protein intake for athletes, and indicate dietary factors that would demand using the top end of the range.
Describe the recommended fluid replacement strategies to use before exercise, during exercise of different durations, and following exercise.
Describe the salt requirement of the athlete compared to that of the sedentary individual and the recommended means of maintaining sodium balance.
Provide a brief summary of the effects of vitamin supplementation on performance.
Characterize the role of the precompetition meal on performance and the rationale for limiting fats and proteins.
Explain why one must be careful in recommending specific body fatness values for individual athletes.
Carbohydrate Diets and Performance
Carbohydrate Intake Prior to or During a Performance
Carbohydrate Intake Post-Performance
Water and Electrolytes
Fluid Replacement—Before Exercise
Fluid Replacement—During Exercise
Fluid Replacement—After Exercise
Body Composition and Performance
This chapter on nutrition, body composition, and performance is an extension of Chap. 18 because the primary emphasis must be on achieving health-related goals before performance-related goals are examined. In fact, the information presented here must be examined in light of what the average person needs. From this perspective, the exercise scientist might then ask fundamental questions about nutrition, such as, does an athlete need additional protein? Or, what percentage of body fat is a reasonable goal for an athlete in a particular sport? We will address these questions in that order. For a more detailed look at these issues, see Suggested Readings for Clinical Sports Nutrition by Burke and Deakin, Nutrition for Health, Fitness and Sport by Williams, Anderson, and Rawson, and the 2016 ACSM position stand on Nutrition and Athletic Performance.
In Chap. 18, we indicated the recommended range of nutrient intakes: