Saturday, October 23, 2010

How Not To Bonk In A Marathon

A fascinating post by Amby Burfoot:

"The mathematics in Rapoport's paper are, frankly, beyond most of us (me, anyway). But he has developed an online calculator at to simplify the process. After all, the main goal behind his work is to make "computational marathoning" (my words, not his) accessible to real-world marathoners. He wants runners to understand that The Wall is not an inevitability; it only results from inexact science."

I have a theory that if you have a fat-optimized metabolism you may be able to adapt a different fueling strategy.  Our hunter-gatherer ancestors probably didn't have to depend on finding a nice source of carbs every time they set out to run down dinner, and bonking in the middle of the savannah would clearly not be a survival trait.  Unfortunately I have no evidence to support my suppostion, since most modern competitive runners have adopted a carb-based fueling strategy.

But this issue may well highlight the line between our persistence-hunting ancestors and a modern competitive runner.  It seems to me that if there is a case where "Chronic Cardio" would start to become a problem to your health, this is likely over the wrong side of that line.

I'm not endorsing the notion of Chronic Cardio, btw, and I hope to do a post soon explaining my problems with that theory.


  1. What does your "different fueling strategy" look like? I use a carb-based strategy for races and training, but having just read "Primal Blueprint" I'm a bit behind on the learning curve. This past week I substituted all my lunches for something Primal approved, and in general cut my carb intake way back. But during my half marathon today I didn’t feel so great. Could be the changes in diet, but I’m not sure.


  2. I don't just eat carbs. i have protein and fat. My favorite fat source prior to heading out is whipping cream in coffee, and during the run it's macadamia nuts, which contain high amounts of alpha-linolenic acid, the vegetable-based omega-3 fatty acid. I've heard that the body converts ALA to ATP, and Wikipedia tells us that muscles prefer fatty acids as a fuel source. Macadamia nuts also have some protein and carbs. I've found that I start craving some carb sources after a while, and I usually use apples or bananas.

    But over time I am using less and less carbs on runs, and my post run meals usually have little to no carbs, but lots of protein.

    But I'm far from an elite runner, and my approach might cripple an elite runner. So don't come crying to me... ;)

  3. Oh, and the problem with macadamia nuts is that it's tough to chew them and breath at the same time. I got the idea for nut-fueled running after reading that the Afghans run circles around our Special Forces on a handful of nuts. They're often barefoot, of course.