Hitting the wall

Common card · No. 357239

In endurance sports such as road cycling and long-distance running, hitting the wall or the bonk is a condition of sudden fatigue and loss of energy which is caused by the depletion of glycogen stores in the liver and muscles. Milder instances can be remedied by brief rest and the ingestion of food or drinks containing carbohydrates. Otherwise, it can be remedied by attaining second wind by either resting for approximately 10 minutes or by slowing down considerably and increasing speed slowly over a period of 10 minutes. Ten minutes is approximately the time that it takes for free fatty acids to sufficiently produce ATP in response to increased demand. During a marathon, for instance, runners typically hit the wall around kilometer 30 (mile 20). The condition can usually be avoided by ensuring that glycogen levels are high when the exercise begins, maintaining glucose levels during exercise by eating or drinking carbohydrate-rich substances, or by reducing exercise intensity.

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