How Do You Know If You’re Bonking and What to Do About It 1

Bonking Title Image

If you are an active individual and have done any type of long distant training, whether it is for a bike tour, race, or even running, you may have heard of the term “bonking.”  This is what some runners refer to as “hitting the wall.” Bonking is certainly something you don’t want to experience when you’re on a tour and really shouldn’t even be close to bonking. Let’s first talk about what bonking is.

Why Does This Happen?

Bonking happens when your body depletes all the glycogen needed to help it burn energy. In a previous post, we know that glycogen comes mainly from carbohydrates. Glycogen is actually produced in about 12-24 hours after a meal. That is why having a good high carbohydrate dinner and breakfast will help you build up your supply of glycogen, ready to be consumed on your ride.

If you’re pushing yourself at 70% to 80% effort when you’re exercising for about 2 hours straight without out eating, you will most likely feel the bonk coming. What happens is your body will shut down, not allowing you to continue the high performance rate. You won’t be able to spin as fast on a bike or power through the hills with the same intensity even if you try. Some symptoms is the overwhelming feeling of dizziness, light-headed, or nauseousness. You feel like you just can’t continue.

A Brick Wall

Photo Credit: wwarby via Compfight cc

This Really Shouldn’t Happen

Bike touring isn’t really a high intense activity unless you choose to make it that. Whenever I’m on a bike tour, I try to take it easy and not overexert myself. I would say I put in about 50% to 60% of effort, at most, when riding. I also take advantage of coasting (not pedaling) whenever a downhill comes my way. This should allow you to use up your glycogen at a slower rate.

You might be asking, “Why doesn’t your body try to burn fat?” Your body doesn’t really burn fat as efficiently as it does carbohydrates. Yes, it can burn fat directly, but it does prefer glycogen. Therefore, the bonk will still occur even if you have fat to burn. This actually leads us to our next steps of what to do.


Photo Credit: jDevaun.Photography via Compfight cc

What To Do When You Think You’re Bonking?

Most people think they’ve bonked, but still have some glycogen left in their system. Therefore, you should pull over to the side of the road and refuel with some carbohydrate snacks or sports drinks. Because it takes some time for your body to produce glycogen, it is wise to take it easy and not overexert yourself. See if you can still ride at a reduced performance level. Perhaps just walking your bike will help. But if you feel your body is completely shut down, it is best to stop and call it a day. Either figure out a place to camp for the night or rest until you feel better to ride.

How Do You Prevent It?

It is best to avoid bonking by doing the following things.

  • Eat a high carbohydrate dinner before you ride.
  • Eat breakfast the morning of the ride.
  • Consume snacks during your ride.
  • Be sure to drink plenty of water before and during the ride.
  • Don’t eat too much carbohydrates as well. Your body won’t be able to process it that fast.
  • Eat after you’re done with your ride to continue the production of glycogen.

Breakfast in Santa Barbara

My Experiences

I’ve personally bonked 1 or 2 times in my life, but luckily, it wasn’t bad. I was able to continue on, but at a much slower pace. In fact, the first time occurred on my first bike tour to Cachuma Lake. The first day, we rode our bikes for over 100 miles for the day. We actually decided to wild camp because I couldn’t move further. I was confused because I had just had dinner an hour before. But this all makes sense now since my body was probably still trying to produce glycogen from the meal. The next morning, I felt better. At least good enough to ride 20 miles to a park for us to have breakfast.

About Johnny Lam

Johnny is an avid cyclist who enjoys bicycle touring as well as anything bicycle related. Johnny has traveled the entire Pacific Coast by bike from Vancouver to the border of California and Mexico. He's also toured through-out locations in Southern California. Johnny is also a League of American Bicyclists League Certified Instructor (LCI) and also completed the Adventure Cycling Association's Leadership Training Course (LTC). He is an active member in Los Angeles bicycling community being involved in organizations like the Los Angeles County Bicycling Coalition (LACBC), C.I.C.L.E. (Cyclists Inciting Change through Live Exchange), and Bike San Gabriel Valley (Bike SGV) by taking part in ride marshaling, pedestrian & bike counts, and other volunteering opportunities.

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