What It Feels Like to Hit the Wall

“Hitting the wall” or “Bonking” is a term used by runners and bikers to describe glycogen depletion which leads to sudden fatigue and energy loss. In all my running, I had never experienced it – until recently.

Photo Credit: sebastien.barre

I was looking forward to the November trail race my girlfriend and I had signed up for at the China Camp Basin (she’d do a 10k and I’d do the half marathon).

Unfortunately, we suffered a brain fart and went there on Sunday rather than Saturday and missed the race. Whoops. It wasn’t all bad as we hiked the trail together for 2 hours instead and went oyster shucking at Point Reyes afterward.

Still, I was annoyed at missing the race. I had been looking forward to pushing myself, so I decided to run a fast 13 miles on my own instead. And that’s when I learned what it’s really like to hit the wall.

Getting to Empty

I went on my usual route that followed the Embarcadero along the water all the way to the Marina (the top of San Francisco) and back. I wasn’t feeling super rested that morning, but I was able to maintain around a 9:30-10min/mi pace which is faster than my usual long run, but slower than previous race paces.

I started getting hungry 40 minutes in but waited until the half way mark, 6.5 miles, to eat my one energy gel. As I headed back, I felt myself getting tired, but I really kept pushing hard.

“This is a race! Go all out and finish exhausted!” I told myself.

This pep talk got me through miles 7-11 but at mile 12 I started feeling really tired and hungry. I was frustrated but slowed, recognizing that I still had 2 miles to go.

The Bonk

That 12th mile took forever. I had my eyes closed for most of it (very bad idea, don’t do this) because I was so uncomfortable and just wanted to zone out completely.

When I finally made it to mile 13, I was basically shuffling. I didn’t want to walk because I knew if I did, I wouldn’t want to start up again. I was starving and it felt like the air had become thick and resisting my motions. Every step was a struggle.

Finally around 12.5 miles, I literally collapsed on my hands and knees. I couldn’t go any further. I walked the last .5 miles, just about finishing 13 miles (without the extra .1)

See my Runkeeper activity for this run.

When I got home, I stuffed my face with snacks and microwave meals (I know, the food of champions). It took a few hours of food, drink, shower and rest before I really felt myself again.

What It Means, Physiologically, to Hit the Wall

There’s a lot more science than I can touch on here but basically it appears I ran out of glycogen, which breaks down into glucose and is one of the primary forms of energy in the human body (the other is burning fat).

The more intense your activity, the more glycogen you use (compared to fat). During most long runs, I maintained a 11 min/mi pace, which is much easier on the body. During races, I would typically carbo-load, stuffing extra glycogen into my liver and muscles, and have several energy gels or drink lots of gatorade during the run.

Because I was running hard and didn’t replenish my energy sources fast enough, I ran down to nothing and crashed. Your brain uses a lot of glycogen too which might explain why I wanted to close my eyes – your mind starts working poorly when you’re low on energy, just like your muscles.

Additional Resources

I’m glad I had a chance to experience “the wall” but I don’t ever plan on doing it again. I found some resources on glycogen depletion that you might find useful as well.

Have you ever hit the wall? I’d love to hear your stories in the comments!




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Jason Shen

Jason is a tech entrepreneur and advocate for Asian American men. He's written extensively and spoken all over the world about how individuals and organizations develop their competitive advantage. Follow him at @jasonshen.

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  1. Man.. Definitely know what that’s like. Went to a 12 mi meetup run. I’d never been to one before and unfortunately tried to keep up with a group I shouldn’t have. It didn’t help that the only thing I had eaten was a late lunch the night before. I kept a ~8 min pace for the first 10 mi, which was MUCH faster than I was used to running. I completely stalled out and walked the next two miles… The route ends at a Starbucks and my brain must not have been working correctly because I bought a can of Starbucks Refresher and chugged it. Not pleasant on the stomach.

    • @doyulikejin The no food thing will kill you! Way to tough it out – amazing how going with other people can push you farther that you expected eh?

  2. Hi Jason, I’ve been enjoying your blog.  I think races are 100% mental.  I can only speak for running because that’s all I’ve done, but when I’m running solo and accountable to no one but myself, I poop out earlier than I should; every step is grueling.  When I’m racing surrounded by a whole community of runners, I have to keep up.  There’s no turning back, there’s no slowing down, get across the finish line and then rest.  I’ve hit that wall.  I almost threw up.  But kept going.  It’s do or die.  I don’t know if you’ve seen the picture making the rounds online of a man running a race with a sign on his back that says, ’50, Fat, Diabetic, Ahead of You.’  I love that.  Whenever I hit a wall during a race, I quickly look around for those people who are ahead of me, and press on.

    • @cgacad Glad you like the blog and this post!
      It’s been shown that people work harder and longer when they are with other people and even when they think they are racing against the time of someone else who just finished. The second half of my marathon was like that – running till the next mile marker, walking, and running again.
      However, to say it’s 100% mental is simply not accurate. Your muscles require energy to keep working, as does your brain. If you do a bad job of fueling there are very real consequences. As an extreme case imagine if you fasted for 3 days before a big race.

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