Nike's 'Moonshot': What Will It Take to Run a Marathon in Under 2 Hours?

When Kenyan runner Dennis Kimetto passed under the Brandenburg Gate and stormed to the finish line of the Berlin Marathon in 2014, spectators saw an incredible number flash before their eyes: 2:02:57. Kimetto had set an astounding new world record and became the first man to run a marathon in under 2 hours and 3 minutes. And while that feat already seemed superhuman to some at the time, others had, decades earlier, set their sights on a far more ambitious — and perhaps even impossible — goal: breaking through the 2-hour barrier in the marathon.

Now, three athletes stand poised to chase down the historic milestone as part of Nike's Breaking2 project. Reigning Olympic marathon champion Eliud Kipchoge, current half-marathon world-record holder Zersenay Tadese, and Lelisa Desisa, winner of the Boston Marathon in 2013 and 2015, will attempt to run 26.2 miles (42.2 kilometers) in less than 2 hours on Saturday (May 6) at the Autodromo Nazionale Monza, a Formula One racetrack located north of Milan, Italy. This weekend's attempt is being heralded as a "moonshot marathon," one that Nike formally announced six months ago to much fanfare.

But can it be done? Posting a finish time of 1:59:59 means sustaining a blistering pace of just under 4 minutes and 35 seconds per mile for 26.2 miles. And though shaving 3 minutes off the current world-record time may seem like a small gap to bridge, at this sport's elite level, cutting finish times down by even 1 minute can be a gargantuan effort. [In Photos: How to Build the World's Fastest Marathoner]

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"Usually it takes 30 years to make such a big improvement in a record time," said Wouter Hoogkamer, a research associate in the Department of Integrative Physiology at the University of Colorado, who studies biomechanics, energetics and the neural control of running. "It's going to be such a huge effort to take those 3 minutes off the world record."

Pushing the boundaries

Many liken the feat to Roger Bannister breaking the 4-minute mile. In fact, Nike's Breaking2 attempt will take place 63 years, to the day, after Bannister made history at the Iffley Road Track in Oxford, England, where he finished the mile in 3 minutes 59.4 seconds. But while both hold historical significance, that's where the similarities end, according to Mary Wittenberg, CEO of Virgin Sport and the former president and CEO of New York Road Runners, where she also held the position of race director of the New York City Marathon.

"This is more like climbing Mount Everest," Wittenberg told Live Science. "There's much more variability in this than in breaking the 4-minute mile — in the simplest terms, because it's so much longer. If Kipchoge wakes up not feeling 100 percent, you can win a race, but can you run faster than anyone has ever run before for 26 miles? It's a much longer quest. It's not quite like going to the moon — I wouldn't put it quite there, but it's more in the realm of Everest."

The elusive sub-2-hour marathon has long been something of a holy grail for those in the running community. In 1991, Dr. Michael Joyner, an anesthesiologist and expert in exercise physiology and human performance at the Mayo Clinic in Rochester, Minnesota, published a paper that was the first to explore human physiological limits in the marathon. Though he still shies away from calling it a "prediction," Joyner's research looked at the most important components of an elite athlete and then imagined what could be possible under the most ideal circumstances.

Pieces of the puzzle

In the 1970s and 1980s, researchers started identifying three main pieces of the puzzle that determined an athlete's running performance over long distances: maximum oxygen consumption, lactate threshold and running economy. Maximum oxygen consumption, or VO2 max, is defined as an athlete's aerobic capacity, or how much oxygen it costs an athlete to run at a given speed. In other words, it's the capacity of a runner's engine.

The lactate threshold can be thought of as the intensity at which blood lactate levels that are produced by the muscles during exercise begin to exponentially rise, essentially at a faster rate than it can be removed by the body. When runners reach a pace where it becomes uncomfortable to talk, this is usually considered the athlete's maximum steady stage before hitting the lactate threshold, Joyner said. Finally, running economy refers to how efficiently a runner can convert oxygen and fuel (from sources such as carbohydrates) to power their output — similar to a car's gas mileage. [5 Coaches' Tips to Make Sense of Your Running Data]

By calculating the physiological limits for each of these three values, Joyner's model found that the fastest possible marathon time could be 1:57:58.

"Scientific modeling isn't always about making a prediction," Joyner told Live Science. "It was a modeling exercise to say: How do all these pieces of the puzzle fit together to explain elite performance? Then, you say, 'OK, what's the upper limit predicted by this model, and why hasn't it happened yet? Where are the gaps in our knowledge?'"

Nike has enlisted a team of scientists to try to fill some of these gaps in knowledge, including how to improve an athlete's running economy, how to craft more effective nutritional plans for elite runners, and how to build a better running shoe.

"What they're doing is taking a whole host of these interventions and improving all of them a little bit and hoping all the improvements across the various interventions will result in a few minutes being taken off the world record," said Trent Stellingwerff, leader of innovation and research and a nutrition expert at the Canadian Sport Institute.

Earlier this year, Hoogkamer and his colleagues built on Joyner's early findings and focused on finding biomechanical ways to improve an athlete's running economy.

"We weren't changing the physiology of the runner, but helping to make it easier for that runner to run at a specific velocity," Hoogkamer said.

New shoes

One of the key things the scientists looked at was improvements in shoe technology. Nike and Adidas have both designed new shoes to help runners break the 2-hour marathon barrier. Nike's shoe, the Nike Zoom Vaporfly Elite, features lightweight knitted material in the upper part of the shoe; a full-length carbon fiber plate to minimize energy loss; a foam sole made of a lightweight material, dubbed ZoomX, that Nike says is lighter than standard foam; and an upturned heel to reduce drag.

According to Nike, the innovative new shoe, which has been customized for each of the three athletes making the sub-2-hour attempt this weekend, could boost an athlete's running economy by 4 percent. That, in itself, could push an elite athlete already capable of running a marathon in around 2 hours and 3 minutes under the 2-hour barrier — at least on paper.

"If a shoe is saving 4 percent of energy — that, on its own, is crazy," said Hoogkamer, who isn't part of Nike's Breaking2 project, but whose lab was commissioned by Nike to conduct independent tests on their new Vaporfly shoes. "People have been trying to make better running shoes for years and years. That's definitely a game changer."

Hoogkamer and his colleagues conducted treadmill tests to see whether, and how, energetic savings translate to time savings. The scientists found that a shoe that is 1 percent heavier made a person run 1 percent slower on a treadmill, which means a shoe that promises 4 percent energy savings could theoretically help an athlete run 4 percent faster. But, the researchers conducted these tests on shorter time trials, not the full marathon distance.

"I think 4 percent of energetic savings on a treadmill should be enough to run 2.5 percent faster, but I can say whatever I think from theory. It's up to the runners to actually show it's possible," Hoogkamer said.

A new world record?

Nike chose a Formula One track in Italy for this sub-2-hour attempt because most existing marathon routes are not optimized to try to post the fastest finish time in history.

"These courses in big cities have all these 90-degree turns, which slow runners down," Joyner said. "Having just one big loop makes a lot of sense because you're also minimizing hills."

Nike has said that though the Formula One track in Italy will be ratified by the International Association of Athletics Federations (IAAF), the sport's governing body, their attempt tomorrow will not be for an officially sanctioned world record. (An officially sanctioned world record requires following a strict set of criteria for the course and the pacers involved, and also requires athletes to pick up their own water bottles rather than being handed them during the race, among other factors.)

And while this does nothing to lessen the difficulty of the task, for some, it changes the meaning of the milestone.

"I think if you're going to break sub-2, you have to do it within the rules of the sport," Stellingwerff said. "Otherwise, you could just find a massive downhill and have people run the whole thing downhill. The pursuit is a bit pointless to me if it's not done in the spirit of the rules."

But others think breaking the 2-hour barrier — whether it's an officially sanctioned world record on the first try or not — is valuable for the sport of running as a whole.

"Would I want to see a race put all their resources into this? No, because they have a lot of other participatory things to take care of," Wittenberg said. "But, this is Nike, and they're going to spend the money somewhere. So, the fact that they have a galvanizing campaign internally to push them to innovate — that's great for their culture and I think that's where this is a win for the sport."

So, whether the record is broken tomorrow or 10 years from now, the running community will benefit, Wittenberg said.

"When you talk about defining perceptions about human limits, the conversation is going to be about going to the moon, or going to Mars, or climbing Mount Everest. I think breaking the 4-minute mile and breaking the 2-hour marathon is great for running because we're in that conversation," she added. "In that way, I think it's great."

Nike will be live streaming its Breaking2 attempt on Twitter and Facebook, beginning at 5:45 a.m. local time in Monza, Italy (11:45 p.m. ET, or 8:45 p.m. PT).

Original article on Live Science.