During an intensive bout of exercise, your body can use up to 200 or even 250 grams of carbohydrates depleting your full store of glycogen, or stored glucose. Once your exercise is finished, those carbohydrates need to be replenished quickly to keep you at your peak athletic performance. Refueling your body and rebuilding stores of glycogen, or stored glucose, is the last critical step of training.

All forms of carbohydrates are made with sugar molecules. Carbohydrates were once broken into categories according to the complexity of their molecules, or simple carbohydrates and complex carbohydrates, with the complex variety being much preferred for athletes and others on healthy diets. Now, however, it’s been widely acknowledged that the proper breakdown of carbohydrates doesn’t fall into two clean-cut categories.

Glucose is simply blood sugar, and eating carb-rich foods prior to working out will initially raise your blood sugar. To counteract this flood of glucose, the body releases insulin, which is produced in the pancreas and insulin then moves the glucose out of the bloodstream and into the cells. When glucose arrives in the cells, it is used immediately for energy.

Diets high in carbohydrates are essential for athletes, but as discussed in Carbohydrates: The Body’s Core Fuel For Energy, finding the right balance of fuel for your body is about much more than what you eat. Properly preparing your body for work-outs is a balancing act of what sorts of carbohydrates you eat and when you eat them.

Okay, but what type of carbs should the athlete be eating? The reason carbs have a bad reputation is because there are lots of low-quality sources out there, in the form of junk foods and other convenience foods that don’t offer any real nutrition – people fill up on them and pack on the pounds, but are still starving for nutrients. Over consumption of simple sugars (mono and disaccharides), like those found in candy and soda, has also been linked to the onset of type 2 diabetes and obesity. These types of carbs have a high glycemic index, which means they cause your blood sugar to rise rapidly and then eventually crash. The exception to the rule is the simple sugar found in fruits. Because fruits contain fiber, vitamins, minerals, anti-oxidants and other goodies, they generally prevent the sugars from being absorbed so rapidly in your system, so you don’t get that crash.

Contrary to what some fad diets would have us believe, carbohydrates are not the enemy. In fact, they are pretty much the athlete’s best friend. Carbs provide the foundation for any serious athlete’s diet. Why? Because anytime you engage in moderate to intense exercise, your body is using glycogen (stored carbohydrates) as its primary fuel source.