Bonking, hitting the wall, the knock. Whatever you call it, running out of energy is something that every cyclist dreads. It is the result of exercising to the point at which your muscles’ glycogen (energy) stores become totally depleted. Glycogen is the stored state of carbohydrate within the body and it’s the primary fuel you use during high-intensity exercise - once these stores are empty, your body is running on fumes.
The principle is similar to that of a car. As it runs out of fuel, it will come to a gradual stop and, to to get it started again, more fuel is needed. This is the same in cycling: the right fuel is needed at the right time to help maintain sufficient levels of glycogen in the body, and prevent the dreaded ‘bonk’.
