In a few days Nike is staging a race in Monza, Italy,

where competitors will be attempting

one of the greatest feats of athleticism in history.

A sub-2-hour marathon.

(African drum music)

To do it, Nike's tapped three of the world's

very best long distance runners.

And if any of them is to break two hours,

he'll need to maintain an average pace

of at least 13.1 miles per hour,

for 120 consecutive minutes.

Now 13.1 miles per hour is obviously very fast,

but it's not so fast as to be unreachable,

by even an average runner.

The challenge is in maintaining that pace.

And so, in that respect,

what distinguishes a world-class distance runner,

from an average one.

To answer that question we've done two things.

First, we invited members of Wired's running club

to see how long they could last

on a treadmill running at 13.1 miles per hour.

And second, we called this guy.

My name is Michael Joyner, I'm a physician, researcher

at the Mayo Clinic and I'm an expert in human performance.

[Robbie] So how'd we do on the treadmill test?

[Man] Alright, you got this.

(African drum music)

(whirring of the treadmill)

[Man] Nice. (applauding)

That's, that's impossible. (gasping)

Actually, it might not be for everyone.

Joyner's not affiliated with the Nike initiative,

but he has been studying the marathon's

two hour threshold for decades.

In 1991 he published a paper exploring

the theoretical limits of marathon running.

He calculated that an ideal athlete,

running under ideal conditions,

could run a marathon in 1 hour 57 minutes 58 seconds.

We asked him to explain why none of us will ever

run a marathon that fast,

but why one of these guys just might.

[Michael] Three things that determine

distance running performance are VO2 Max,

for maximal oxygen uptake,

lactate threshold, and running economy or efficiency.

VO2 Max is basically a measure of how much oxygen

you can get out of the air and into your tissues.

It's typically expressed in units of milliliters of oxygen,

per kilogram of body weight, per minute.

If you don't exercise but are otherwise young and healthy,

your VO2 Max is likely in the 30s or 40s.

If you do exercise by running, swimming or biking,

you probably see values in the 40s and 50s.

And if you're really serious with your training,

you can even creep into the low to mid 60s.

That's still no where near the numbers you see

in professional marathoners.

The elite athletes that will be attempting

the Sub-2 Marathon, have VO2 Max values

in the 70s or even 80s.

So they have double the VO2 Max values

of mere mortals, and it's a little bit because

they're small men, like putting a V8 into a motorcycle.

If you think of VO2 Max as the size of your engine

relative to the size of your car.

Then Lactate threshold is a little like

the red-line meter in your car's dash.

It's the level of effort at which lactate

and other metabolites start accumulating

exponentially in you blood.

That's a limit you want to avoid overshooting

in an endurance race.

It's usually given as a percentage of your VO2 Max,

and for untrained people, it's around 60%.

With training, the number of mitochondria

in your skeletal muscle and he number of capillaries

around the skeletal muscle go way up.

This permits people to start to work at 70, 80,

even 85 or 90% of their maximum.

So it's like going from having

a tachometer with a red-line on it in your car at 5000,

to a Ferrari with one at eight or nine thousand.

That leaves running economy.

Basically how efficient are you.

There's a lot of theories about why some runners

are more efficient than others,

and most of them boil down to biomechanics.

So basically the length and size of your legs,

how much you bob up and down when you're running,

where your foot lands, relative to your center of gravity,

even the flexibility of your tendons.

But we actually know a lot less about running economy

than we do about either lactate threshold or VO2 Max.

The fact it leads to a lot of myths and misconceptions

about what makes running more or less efficient.

A big one, is that running on your forefoot,

or your midfoot is more efficient than landing on your heel.

But that's not exactly true.

In 2012, a biomechanics researcher named Ian Hunter

shot this footage of elite distance runners

competing in a 10,000 meter race.

Now I want you to focus on their feet.

If you watch closely, you'll notice that their strides

actually vary quite a bit.

Some runners land on the forefoot,

some land on their midfoot,

and still others land heel first.

All of which suggests, there's actually no single

most efficient way to run.

In fact, it tends to vary quite a bit

on a case by case basis.

The irony here is

that even if we don't totally understand it,

running economy is the one variable

that's most sensitive to technological enhancement,

which is why so many shoe companies

are experimenting with ultra-light materials,

super springy foams, and perpulsive carbon fiber plates.

All of which by the way, Nike has included in its new shoe,

which it claims, will boost the efficiency of its runners

by as much as four percent, which is crazy.

Especially when you consider how efficient

these guys are to begin with.

[Michael] The one thing that's been noted

about the East Africans,

is not so much that they have very high VO2 Max values,

or anything unusual or out of this world,

or lactate thresholds, although they're plenty high.

What's really interesting about these individuals

is a large number of East Africans

have terrific running economy or efficiency.

[Robbie] Us on the other hand, not so much.

(faint clapping)