Sports Nutrition: Energy Metabolism and Exercise

Book Preface

The interplay between nutrition and physical activity is as frequently misunderstood as the relationship between industrialization and global climate; most people tend to either underemphasize (“as long as I get enough exercise I can eat whatever I want”) or overemphasize (“each mouthful of food must conform to rigid requirements”) the importance of nutrition to exercise performance. Making sound nutritional choices does not guarantee athletic prowess but consistently making poor choices almost certainly constrains performance. More specifically, sound nutrition is necessary to effectively train and take advantage of training stimuli. From the 1920s studies of high carbohydrate versus high fat diets on exercise performance by Krogh and Lindhard 1 through the 1960s glycogen supercompensation studies of Bergstrom and Hultman, 2 to the more recent studies of post-exercise protein feeding on muscle protein synthesis, 3 it is clear that total energy and the macronutrient (i.e., carbohydrate, fat, protein) composition of the diet modulate acute exercise performance and adaptations to training. Understanding how energy is produced and how the demand for energy during exercise drives energy utilization is critical to recommending appropriate dietary choices to replace that energy and refuel for the next exercise bout. The goal of this chapter is to outline these basic principles of energy metabolism and introduce the concepts that will be reviewed in more depth in later chapters.