Will Carbohydrates Help You Train Harder? by Jerry Brainum

 

In recent issues of Applied Metabolics, I've discussed the results of research findings that provide more practical information on precisely which and how much of certain nutrients are required to help develop additional lean mass and strength. While individual nutritional requirements tend to vary, depending on such factors as genetics, response to exercise, and recovery ability after training, certain principles are general enough to be applicable to most of those involved in weight training, whether for recreational or competition purposes. One of the more contentious topics in sports nutrition is carbohydrates. As I pointed out in my recent article about precise supplement doses and timing in the February issue of Applied Metabolics, nearly all of the published scientific research that has examined the carbohydrate needs of those engaged in sports or exercise has been more relevant to endurance activity, especially extended endurance sports such as long-distance running. The precise need for carbohydrates in those whose activity consists largely of weight-training or resistance exercise is far more nebulous. Indeed, most of the suggestions offered as to the precise amount of carbohydrates needed to power intense weight-training sessions and to promote muscle gains have been either entirely based on previous suggestions for endurance training or amount to simply guesswork based on the breakdown of glycogen that occurs during a typical weight-training session.

Glycogen is the storage form of carbohydrate found in the body. Unlike fat, where storage seems almost infinite, the storage of carbohydrates as glycogen is limited. The body stores glycogen in the liver and in muscles. Glycogen itself is a type of complex carbohydrate, consisting of long branched chains of glucose, the most elemental form of carbohydrate (monosaccharide), and the sugar that circulates in the blood. The amount of glycogen stored in the liver is enough to supply the body with about 12 hours of glucose release until the liver glycogen stores become depleted. This process of the breakdown of stored glycogen in the liver is known as glycogenolysis and occurs in response to various signals relayed in the body. Some of these signals involve hormone interactions. For example, the release of stress hormones, such as cortisol and epinephrine from the adrenal gland can lead to a rapid breakdown of liver glycogen. This is done to provide energy as glucose in the blood to power the "fight or flight" activity typical of acute stress reactions. An important point is that the glycogen stored-calories of 1,500 to 2,000 in the liver is available for systemic use; that is, it is released into the blood circulation. In contrast, glycogen stored in muscle lacks a particular enzyme that would allow the glucose resulting from the local breakdown of glycogen in muscle to enter the blood. As a result, the glycogen . . .