“Oh dear! I might have to get off and walk…”

It’s not often you think that when you’re riding a road bike! I was completely out of energy and out of power. I was on my own, riding on the flat, with a tailwind – and literally struggling to turn the pedals over. The 5km to home, which I’ve ridden hundreds of times before, suddenly seemed like an impossible distance. My power meter was below 50W when I’d normally be up around 200W. As I pulled up at the lights, I wobbled about like a roadside weed in the breeze. I was in the grips of the endurance athletes’ greatest foe – the BONK!

the wall.jpg

Wikipedia defines the bonk (aka “hitting the wall”) as:

“a condition caused by the depletion of glycogen stores in the liver and muscles, which manifests itself by sudden fatigue and loss of energy. Milder instances can be remedied by brief rest and the ingestion of food or drinks containing carbohydrates. 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.”

It’s been a long time since I last bonked, and I’ve never bonked this hard. Over the years I’ve learned my limits – I know how long and how hard I can go before I need to eat. The truth is, it’s been so long since I last bonked that I no longer worried about it. That complacency allowed me to make a number of mistakes which, when combined, put me on the BONK-ville express!

Mistake 1. “The condition can usually be avoided by ensuring that glycogen levels are high when the exercise begins…”.


Last night at 7pm I ran a half marathon in training. (“1:48 actually, thanks for asking!”) This was a little Strava challenge, so I could get a dinky little “February half-marathon badge” on my dashboard. (I thought I may as well get something out of all this running I’d been doing in January!) Plus I’ve packed on a few kilos during the festive season so I decided not to refuel after the run. I believe scientists describe this as “depleting my glycogen stores”.

Mistake 2. “The condition can usually be avoided by… maintaining glucose levels during exercise”.

I never take gels on my Monday morning ride. It’s a 2hr ride that I’ve done dozens of times. Never needed them. And, like all real men, I drink water.

Mistake 3. “The condition can usually be avoided by… reducing exercise intensity”.

It’s been six weeks since I last rode a bike. I’ve had a very relaxing holiday (“NZ actually, thanks for asking!”) and this was my first session back. We were riding a fast 4km circuit in groups of 4. I was planning to coast around and build into things, but somehow I found myself in the front pack with the 3 strongest riders. For a lap and half I felt good and took my pulls on the front. Then suddenly there was a surge and two of us were out the back. We chased but couldn’t catch. After 3 laps we regrouped, but this time I only lasted one lap before I watched them disappear down the road. I had nothing.

There’s nothing quite like watching the bunch slowly pull away from you. It’s quite sad! The last 3 laps I spent trying to stay ahead of the 12-year old who was closing in on me. Rather than “reducing exercise intensity”, I’d increased it (relative to my current fitness levels)!

And so I bonked.

Bonk - Heart Rate and Power

The ride home is a fading memory. I got progressively weaker. By the time I left the bunch (about 6km from home) I’d slowed to a crawl. I did a mental inventory of my saddle bag, hoping to remember some months-old race gel. I wanted a shop but couldn’t face diverting even further from home. I wondered whether I could actually slow down enough that my body would stop complaining. I thought about walking. At 2km from home I considered ringing my wife!

Somewhere under all that suffering I realised, with a wry smirk, that I was learning yet another valuable lesson! Isn’t life kind like that?

Soon I head out for my second ride back. The scars are fresh. I shall carry a gel (or two). I will not bonk!

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2 Responses to Bonk

  1. I started to feel one coming on when riding on Sunday; it was between 1 and 4 degrees C, and I didn’t eat enough breakfast… fortunately I made it to a cafe, poached eggs on toast, coffee, more coffee, and cake. The rest of the ride wasn’t too bad.

    Hope the recovery from the bonk isn’t too bad; it can really take it out of you.

  2. jontsnz says:

    Yum. I bet that food went down a treat!

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