Imagine pushing yourself through a long trail run, hike, or bike ride, only to suddenly feel like your body has hit a brick wall—this is the dreaded moment of “bonking,” and it’s something every athlete tries to avoid.
Bonking, also known as “hitting the wall,” is a term commonly used by endurance athletes to describe the sudden and overwhelming fatigue that can occur during prolonged physical activity. It happens when the body depletes its glycogen stores, leaving the muscles without sufficient energy to continue at peak performance. This can result in a sharp decline in strength, coordination, and mental focus, making it difficult to complete the activity. Although bonking can be a frustrating experience, it can be largely prevented through proper nutrition, hydration, and pacing strategies, ensuring that the body is fueled and ready for the demands of extended exertion.
Your body stores glucose, which is a type of sugar, to be used as energy later. From a physiological standpoint, bonking happens due to a drastic depletion of those glycogen stores, to the point where your body can no longer adequately supply working muscles with the fuel needed to produce energy or maintain blood glucose levels. When this happens your coordination and judgement become impaired, muscular function fails, and you can even lose consciousness. All of which can be dangerous, but that risk is compounded if you’re in a remote wilderness setting with limited communication and/or access to medical attention.
Knowing the signs can help you prevent bonking from happening. These include sudden exhaustion, shakiness, weakness, confusion, irritability, heavy legs, inability to maintain pace, nausea, and lightheadedness. If you start to notice any of the previous symptoms, stop exercising or drastically reduce your pace. Sitting or laying down can help with lightheadedness or dizziness. Consume fast-absorbing carbs, such as energy gels, sports drinks with glucose, candy (i.e. gummy bears or Skittles), fruit juice, white bread, honey, or a ripe banana. Rehydrating, using electrolyte drinks, is also an importing step to aid in recovery. Give your body 10-20 minutes of rest to absorb the sugar and stabilize before resuming any activity, however you should avoid returning to intense physical activity right away. Avoid driving until you are fully recovered and get someone to assist you if you aren’t thinking clearly.
Prevention is the key to avoid bonking in the first place. Eating carbohydrates before and during strenuous exercise, staying adequately hydrated, and training properly to increase glycogen storage and efficiently can all help prevent you from hitting the wall. Experts recommend eating/drinking carbs every 30-60 minutes during endurance activities (~30-60g carbs/hour). Also listening to your body and paying close attention for early warning signs will help you slow down before bonking occurs.
If your chosen activity is happening outdoors during hot weather, your risk of bonking increases due to faster glycogen depletion, dehydration, reduced appetite or food intake, increased perceived effort, and increased risk of electrolyte imbalance due to heavier perspiration. In warmer weather you should be eating/drinking carbs more frequently (every 15-20 minutes), adopting a slower pace, wearing light coloured, breathable clothing, and not relying on plain water alone. Water with electrolytes is a better choice.
Bonking can be a critical condition that outdoor endurance athletes must be prepared for. Keeping your body sufficiently fueled, knowing how to recognize early signs, and carrying quick-energy snacks can make the difference between a strong finish and a dangerous setback.
