Spencer Matthews

60 to 70% is this magical zone two.

70 to 80, zone three, often called the gray zone.

80 to 90 would be zone four, and 90 to 100 is zone five.

So they're basically built there to try and help people theoretically work out which fuel source they're using against the objective of their training.

That's quite the answer.

I probably could have done that.

Forgive me.

Again, why don't you advise it out much?

It's a quicker answer, no doubt.

Yeah.

It is, but you can't compare exertion.

So, you know, one person running at a certain speed, the only way you can really think about zones is how it feels.

So, you know, zone two, by its very definition, is staying below what is often called the sort of anaerobic threshold, when your body basically is going to be on borrowed time.

So in zone two...

You're theoretically mostly... And when we look at these energy systems, there's never that you completely use fat and oxygen.

You completely use sugar and no oxygen.

So these systems are always blended.

But if you and I are using fat and oxygen to run...

We can run for a long time.

Me more than you because I've got more fat than you, right?