Digestion and Absorption

Athletes need more energy nutrients, more fluids, and more vitamins and minerals than nonathletes need, and all of these essential substances must go through the gastrointestinal (GI) tract to be digested and absorbed for delivery to organs and muscles. It is critical that athletes be familiar with numerous issues relating to the delivery of nutrients and fluids through the gastrointestinal tract. For instance, understanding gastric emptying enables athletes to adopt the best strategies for delivering the greatest amount of energy and fluids without inducing nausea or vomiting. Understanding the digestion and absorption of nutrients and fluids helps athletes develop optimal methods for delivering needed nutrients and fluids to working muscles while maintaining blood volume (a critical issue for performance). The best food- consumption strategies, based on GI tract function, enhance performance and minimize the potentially damaging effects of poorly timed meals. In cases where iron or calcium supplements are required, understanding GI tract absorption of these minerals will help athletes plan the best way to incorporate them into their dietary intake.

This chapter presents issues to consider when delivering the nutrients and fluids that are in such high need for athletes. The goal is to deliver the most needed nutrients while lowering the risk of gastrointestinal distress, particularly when training and during competition. The information is presented in a way that helps readers understand GI function in exercise and nonexercise situations so they'll acquire the tools to make the best eating and drinking decisions in a variety of situations.

The Gastrointestinal (GI) Tract