Human beings have walked the earth for millennia, yet no one has ever run 26.2 miles -- a marathon, if you prefer -- in less than two hours.

Can it be done? Nike thinks this is year it willbe done. In December, the company announced a lofty goal to break the barrier sometime in 2017. Now, speaking on the record for the first time, three of the principle architects of this quest shared with Mashablejust how the footwear giant plans to break one of the most daunting barriers in human physical performance.

The closest anyone's ever gotten to breaking the two-hour mark on an official course was Dennis Kimetto, a runner from Kenya who ran the 2014 Berlin Marathon in two hours, two minutes and 57 seconds. For historical context, Haile Gebrselassie set a mark of two hours, three minutes and 59 seconds in 2008, while Khalid Khannouchi set a mark of two hours, five minutes and 42 seconds in 2009.

Kimetto's 2014 record is insane, as even the most casual joggers will understand. Imagine running a mile in just under four minutes and 42 seconds. It's enough to make a couch potato want to take a nap -- or puke. Yet that was Kimetto's average pace for 26.2 milesin his record-setting run. To break two hours, one would have to best Kimetto's pace by nearly 7 seconds per mile for 26 miles.

The two-hour marathon has long been a holy grail for distance running aficionados. "To run under two hours without the use of banned drugs would be to set a record that would stand with the four-minute mile as an ultimate test of human stamina," The New York Timeswrote just last May.

But, the paper said, "almost no one considers the feat achievable anytime soon."

Matthew Nurse would beg to differ. He's vice president of Nike's Sport Research Lab, a facility where the company tests potential products and studies athletic performance.

"For several decades, folks have talked about a two-hour marathon," he says "The timing is right now. We think it's attainable."

How Nike will attack the mark

This much is certain about Nike's attempt to break the barrier: It will come sometime this year. It will feature three runners (more on that in a minute). It will be conducted on a course meeting certification standards of the International Association of Athletics Federations, track and field's global governing body.

Nike employees have spent more than a year scouring the globe for the perfect outdoor course, according to Nurse. Temperature, elevation and wind are the main variables being considered -- an ideal location will have a temperature around 50 degrees Fahrenheit, coupled with low humidity.

"We've scanned the world, day and night, first by continent, then by region, which has led us to some selections where we think the conditions will be ideal," Nurse says, although the ultimate location has not yet been decided.

The race environment is one component of Nike's five-part strategy for breaking the two-hour barrier. Another is selecting the right athletes. The three Nike-sponsored runners who will take on the yet-to-be selected course together are 27-year-old Lelisa Desisa from Ethiopia, 32-year-old ​Eliud Kipchoge from Kenya and 34-year-old Zersenay Tadese from Eritrea.

Those three were selected from an initial pool of more than 50 finalist runners, according to Brett Kirby, lead physiologist at the Nike Sport Research Lab. The group was narrowed to 18 runners, who were brought into the lab for testing in November. Researchers analyzed how the selected runners consume oxygen and expend energy, as well as pored over their past performances at different distances.

"These three emerged as having the optimal combination," Kirby says of Desisa, Kipchoge and Tadese.

The chosen three are backed by the research lab's 60-person staff, which is currently working on the final three components of Nike's strategy: hydration, training and equipment.

Their premise is that the right people -- under the right conditions, with the right support -- can achieve something that for decades seemed beyond the scope of human capability.

From waffle irons to world records

All three runners Nike tapped to attack the two-hour barrier receive personalized training regimens and equipment.

"Each athlete has certain needs and is independent in their own way," Kirby says. "Us understanding these needs build toward their success. They might have specific requirements for certain apparel that lets them manage body heat. Or for psychological and emotional support, or for training."

As 2017 wears on, we'll learn exactly where and when Nike plans to take its big moonshot. But maybe you're wondering whya company that sells athletic apparel would devote so much time and energy to something like this.

It attracts publicity, no doubt -- witness this article for proof. It also shows just how much Nike has grown since company co-founder Bill Bowerman used a waffle iron give the soles of running shoes more traction in 1971. But there's also another reason, according to Brad Wilkins, who leads a group of scientists at the research lab charged with developing concepts for new Nike products.

"What comes out of these big audacious goals is a lot of knowledge about what it takes to get there," Wilkins says. "That knowledge can then be applied to everything we do at Nike, whether you're a couch-to-5K person or an elite marathoner."