Carbohydrates

Abstract

One of the fastest growing trends in current dietary concepts is that of the low carbohydrate diet. These diets promise everything from weight loss to improved athletic performance.2,3 The concept of a low carbohydrate diet is not a new development; in fact, the first notation of a low carbohydrate diet can be traced to the middle of the fifth century. At this time, Stymphalos, a two-time Olympic victor in long-distance running is the first documented case of an athlete using a high-protein, low-carbohydrate diet in an attempt to maximize performance.4-7 Additionally, the famous Greek wrestler, Milo of Croton, a five-time Olympic champion who competed from 536 to 520 B.C. is reported to have consumed a diet that was low in carbohydrates and high in protein content.3,8 Currently, many modern athletes are now touting the accolades of the low carbohydrate diet. Proponents of the modern low carbohydrate diet revolution often attack the carbohydrate as being behind the growing obesity trends in the United States9-12 and promote a reduction in dietary carbohydrate content as a means for enhancing athletic performance.5,9,13-17 However, many sports nutritionists and sports scientists have demonstrated the value of carbohydrate in the diet of athletes and continue to promote diets that are rich in carbohydrate content. 2,5,6,18-20 Overall, there seems to be an increased interest in the use of nutrition as a method for improving health, wellness, and sports performance.5,7,10,11,21-23 With this increased interest, a wide variety of diets have been proposed as methods for dealing with obesity, health wellness, and improving athletic performance (Figure 14.1). Generally, we can classify these diets into categories, which are based on the percentage of dietary carbohydrate supplied by the diet. The categories used to classify these diets range from those that require sparse carbohydrate consumption to those that are rich in carbohydrate content. At present, there is a large debate about the efficacy of the different diets available and their relationship to actual athletic performance. This chapter begins with a detailed discussion that examines the different types of carbohydrates that can be utilized in an athlete's diet. This will include an in-depth look at the concept of the glycemic index and its relationship to the different sources of carbohydrate available in an athletic diet. At this point, how carbohydrates are metabolized are explored in an attempt to clarify why they are important during aerobic and high-intensity exercise such as resistance training. After completing the discussions about the types of carbohydrates and how they are metabolized, the dietary carbohydrate needs of the endurance and strength/power athlete are addressed. Figure 14.1 Types of diets. (Modified from Riley,125 Haff and Whitley.66) © 2008 Humana Press.