Avoiding the Bonk: Tips for Fueling Your Body During Exercise.
Bonking, or hitting the wall, occurs when the body runs out of glycogen, the stored form of glucose and the major fuel source for exercise. Once glycogen stores are depleted, the body must rely on fat for fuel, which is released much more slowly and requires more oxygen to break down compared to glycogen. Bonking can be prevented by ensuring glycogen stores are filled up before setting off, taking in some carbohydrate during the ride, and training the gut to absorb more carbohydrate during exercise. Training too often in a carb-depleted state may even slow you down.