When you are training or competing, your muscles need energy to perform. Glycogen, which is glucose stored in our muscles and liver, is the energy used by muscles. Every time you work out, you use some of your glycogen. If you don’t eat enough carbohydrates, you’ll have fewer glycogen stores, and your muscles may not be able to perform their best.
Carbohydrate loading is a technique used to increase the amount of glycogen in muscles and in the liver. It involves eating extra carbohydrates during the week before a competition while at the same time cutting back on training. Carb-loading is intended for elite athletes such as marathon runners and isn’t necessary for most athletes.