Carbohydrates - How Much Do You Need?

By Carol Dittenhofer, RD, MPH

Muscle glycogen represents the major source of carbohydrate in the body - 300 to 400 grams or 1200 to 1600 calories. There is a strong relationship between pre-exercise muscle glycogen content and the length of time that exercise can be performed at 65% of VO2max (which is the level at which most athletes train and compete). The greater the pre-exercise glycogen content, the greater the endurance potential.

Building up and maintaining glycogen stores during training requires a carbohydrate-rich diet. When adequate carbohydrate is not consumed on a daily basis between training sessions, pre-exercise muscle glycogen content gradually falls and this can impact training and performance efforts. It is essential to replenish carbohydrate reserves on a daily basis.

How much is enough? The typical American diet supplies about 4 to 5 grams of carbohydrate per kilogram per day (your weight in pounds divided by 2.2 will give your weight in kilograms). An intake of 6 to 7 grams of carbohydrate per kilogram body weight per day is adequate for most athletes working intensely for about 1 hour per day. 8 to 10 grams of carbohydrate per kilogram per day for athletes exercising hard for 2 to 3 hours of training per day. Needs may increase up to 12 grams of carbohydrate per kilogram per day for intense marathon training.

Next month we'll discuss the different types of carbohydrates and which are best!!!

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