Luke O'Neill

And this gets back to the VMH in a way, because you have your own storage of glucose, mainly in your liver, in the form of this thing called glycogen.

So in other words, we always have a reserve of glucose in our bodies in the form of glycogen.

And glycogen is a polymer of glucose.

It's those glucose molecules all attached together.

Now when you run, especially in these endurance races,

running events like the 10K, you burn the glycogen and that releases glucose into your bloodstream.

And it's obvious in a way because you need energy, don't you, when you're running for 10K.

And so you will begin to take the glucose from the glycogen and your body burns the glucose to make the ATP that keeps the muscles going.

So that's where the energetics of marathons come from.

And then very interestingly, and again, biochemists work this out, if you run a marathon, people hit what's called the wall.

And it's a sudden onset of fatigue, and they've got to push on through the wall.

It's usually after 30 kilometers.

which is maybe, what, two-thirds of the way through a marathon.

It won't happen on the 10K, probably, because it's not long enough for this.

Very few people running 10K will hit the wall.

But in marathon runners, you do hit the wall, glycogen is all gone, and now you switch to other things for your energy source, including, say, fats and fatty acids.

Even amino acids begin getting burned at that point, right?

And your body can detect this and you feel this awful sluggishness.

And when you pack on through, power on through rather, you keep going and then, you know, the energy still comes from other sources as opposed to glycogen.

That's what the wall is.