Bonk

Also known as ‘hitting the wall’, is an unfortunate race-tanking phenomenon that happens when carbohydrate reserves drop/become depleted, typically occurring after 20 miles in the marathon. Muscle glycogen, the primary source of carbohydrates is the main fuel used during endurance activity. Once these stores become depleted, performance decreases, and runners may experience symptoms such as extreme fatigue, a sudden loss of energy, dizziness, headaches, pain, cramping, and a slew of negative emotions. Hitting the wall is as much mental as it is physical.