“Bonking” is painful, and isn’t about hitting your head

Impromptu trail sculpture guy says, “Don’t bonk”,

While hiking, you’re deeply engrossed with telling friends a juicy story, aren’t paying attention to what’s ahead of you and bonk your head on a low-lying branch. Ouch. While that encompasses bonking your head, that’s not the kind of bonking that athletes refer to. The kind of bonk addressed here involves endurance training. While bonking is typically associated with marathon runners and triathletes, hikers and climbers are no strangers to the dreaded bonk, especially when hiking those long, vertical climbs for many miles, and along very long trails.

The “Bonk” is commonly referred to as “Hitting the wall” and describes a painful state of system-wide glucose depletion during long, hard training, and is dreaded by athletes. Bonking is a form of massive hypoglycemia that physically hurts, and once set-in, hurts for a long time, even after you orally replenish. It’s like your car running out of gas, it can no longer go. But with the Bonk, you can no longer go. Then after you replenish, your body is slow to recover over hours’ time. And if you bonk on your way into a hike, you’ll have to replenish, then hike out in that post-hypoglycemia painful state. Super ouch, I’ve been there and can attest that bonking really hurts. Bottom line is that prevention is essential.

Physiologically, your body stores the glucose needed for endurance training in your muscles and liver in the form of glycogen. Hard exercise triggers the mobilization of glycogen from these stores, which is then converted to useable glucose by the liver in a process called gluconeogenesis. It’s important to replenish carbohydrates after exercise in order to replenish liver and muscle glycogen stores for use in future exercise.

Some symptoms of the Bonk:



Losing your “get up and go”





General weakness

Altered thinking

Body aches

Pain, lots of pain

It’s of utmost importance to immediately replenish during early symptoms of the Bonk. Not doing so can have serious consequences. Again prevention, as well as preparation, are essential. Its also essential to supplement with oral carbohydrates during training, so that you never end up completely depleting your endogenous glycogen stores.

Carbohydrate-loading days before a planned long, hard hike or climb is helpful. Also many athletes eat carbohydrate-rich snacks or sports supplements and drink water every 15 to 60 minutes during training, depending upon the person’s individual needs. I know several trail runners who continuosly nosh on gummy bears washed down with electrolyte-infused water while training in order to maintain adequate blood glucose levels and avoid the painful Bonk.

Some examples of glucose sources (click on the photos to buy any of the products through Amazon)


Sport Beans

Shot Blocks

Honey Stingers

Sport Waffles

Gummy candy

Honey sticks

Fresh fruit like orange wedges or bananas

Sweetened dried fruit


Juice boxes

Bottled juices

Chocolate milk

Chocolate coconut water

Protein bars, not sugar-free

Meal replacement bars, not sugar free

Musubi (shaped white rice)

Trail mix with M&Ms

Fruit jam sandwiches

Clif bars


One thought on ““Bonking” is painful, and isn’t about hitting your head

  1. I have seen this first hand with you and Rebecca! It is scary from all sides. They are important lessons learned and I can use the experience to help or avert others in the future. Ironically, the honey sticks I learns from you, got used for you. Good blog!

    Liked by 1 person

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