Nike's stated desire to break the two-hour marathon barrier started in December 2016 when they announced their Breaking2 project which they called "an innovation moonshot designed to unlock human potential."

A little over a year later — with a frigid morning in Monza, Italy at the Autodromo Nazionale racetrack serving as the backdrop for what had the potential to be a historic 26.2-mile distance — Kenyan runner, Eliud Kipchoge, narrowly missed out on achieving the feat after crossing the finish line with a final time of 2 hours and 25 seconds.

While it was certainly still a triumph for the sport of distance running — with Kipchoge finishing two minutes and thirty-three seconds faster than the official world record of 2:02:57 set by Dennis Kimetto in Berlin in 2014 — some still viewed it as a failure for Nike who hoped the marathon barrier would be lowered and in turn would buoy the reception for their latest piece of footwear: the Zoom VaporFly Elite.

The shoes themselves already had a winning pedigree before Kipchoge's marathon attempt. A similar model was worn by all three medalists in the men’s marathon at the Rio Olympics last summer and utilized by the winners of major marathons in Berlin, Chicago and New York.

This "race sweep" prompted some from the running community to cry "foul" due to the design of the shoe which employed a carbon fiber plate inside the sole and provided 13 percent more energy return and saved 4 percent of the energy needed to run at a given speed.

The New York Times referred to this plate as a "slingshot, or catapult, to propel runners forward," and some sports scientists equated it to running downhill at a 1-1.5 percent gradient.

Bret Schoolmeester, Nike’s senior director for global running footwear, said in March, “We’re very confident we’re doing things within the rules and above board.”

“This is a game changer, in the sense that if the shoe companies get patents and these shoes go onto the market, and they’re in wide use, it does make you wonder if it’ll be a level playing field if people can use these advantages,” said George Hirsch, the chairman of New York Road Runners, which organizes the New York City Marathon.

Nike's attempt at breaking the two-hour marathon was a successful PR tool.

However, many might be surprised to learn that the innovation expert that is touting "spring-loaded" shoes is actually following in the footsteps of a brand who had a similar shoe concept that was also marred by controversy.

Spira Footwear is a relatively unknown name for most people. The brand was founded in 2001 in El Paso, Texas by brothers Andy and David Krafsur, who each respectively quit lucrative careers in law and aerospace engineer to battle for a small piece of the billions of dollars up for grabs in footwear each year.

Choosing to focus on the running market — that to that point was dominated by names like Saucony, New Balance, Topo, Brooks, Mizuno, ASICS and HOKA — Spira challenged traditional thinking by touting patented WaveSpring technology that claimed to reduce the impact on a runner's feet and in turn led to easier recovery and less overall exertion.

Since the technology aimed to give runners a competitive advantage over those in more traditional shoes, USA Track & Field and the International Association of Athletics banned Spira shoes in 2005 from any major competitions — most notably the Boston Marathon.

"The rule is outdated," Andy Krafsur said at the time. "If you go back and [look through] history, all new technology was banned -- from the oversized tennis racket to the aluminum bat to the metal driver."

Race officials saw it decidedly different than Krafsur.

"If you recover faster that means you can run more easily, which means that over time you can run faster and farther," said Steve Vaitones, referee for the Boston Marathon. "Steroids don't allow you to see the baseball better, but if you hit it, it might go 20 to 30 feet more, which could be the difference between a home run and an out."

Spira Footwear ultimately challenged the validity of the ban in November 2005.

While some may have fought the perceived injustice through the legal system, Spira Footwear aimed to drum up even more controversy by doubling down on their bad boy status in running.

"Banned in Boston" became a rallying cry for the brand. This tag-line evolved into offering $1 million USD to any male or female runner who could win the Boston Marathon in a banned pair of Spira shoes (this year's winner received $150,000 USD).

The allure was certainly there; the cash prize had the potential to be the largest payout in the history of professional running.

"We are attempting to bring attention to an outdated and unfair rule," said Andy Krafsur. "There should be no prohibition against the use of shoes like these in competition."

Spira Footwear enlisted the help of Dan Norton, formerly the head of the advanced concepts department at adidas and custom shoe creator for Carl Lewis when he worked at Nike, for a special lightweight running shoe just for the marathon.

"I have worked in the footwear industry for over 30 years and Spira's WaveSpring technology is the first true innovation that I have seen since basically the Nike air," Norton said. "The WaveSpring patent is the reason why I proactively joined the company."

Despite the $1 million dollar financial guarantee, no runners with any real legitimacy of contending opted for the "banned" challenge out of a suspected fear that any race results in unsanctioned shoes would hurt their careers.

But that isn't to say that Spira Footwear wasn't trickling down into smaller races.

Keith Pierce, a track coach from Krum, Texas, and a U.S. Olympic trials hopeful at the time, competed in the shoe at the 2007 Cowtown Marathon in Fort Worth, Texas. He won the race by over 12 minutes.

David Cheruiyot won the 2007 Ottawa Marathon in in 2:10:35 — a personal best by over two minutes — which was also a course record.

When it was time for the 2007 Boston Marathon, Spira Footwear continued to taunt race organizers and governing bodies by filing a lawsuit.

However, it would later come to light that it was dismissed on the grounds that the shoes hadn't technically been banned because the latest iterations of Spira Footwear hadn't actually been inspected by members of the USATF.

Unlike the race the previous year, Spira was well represented at the Boston Marathon.

For one hour and 32 minutes, Spira-clad Kenyan runners, Jared Nyamboki and Josphat Ongeri actually were leading the pack before eventually fading down the stretch. But the brand did manage a victory when Oleg Strijakov of Russia won the Masters "Over 40" division.

"Robert Cheruiyot won the 111th Boston Marathon, but so too did a tiny shoe company out of El Paso, Texas," said CNBC's Darren Rovell. "Spira's bright yellow shoes going along for the ride as two complete unknowns (wearing Spiras) ran away from the pack for the first half of the race," while adding, "Nike ultimately (got exposure) thanks to its branding on the tops of both winners, but it was Spira that may have won the corporate race."

What should have been a joyous time for Spira Footwear was ultimately a fleeting emotion.

That same year, Andy Krafsur was ousted from the brand he helped co-found after a long-simmering feud with his brother, David, erupted over what he believed was an attempt to create products that actually competed with Spira.

At the time, the company had done $6 million USD in sales the previous year and was shipping to 40 countries worldwide.

"My brother is upset because we're growing quickly and we're adding good people to build a big company," Andy Krafsur said. "He's a myopic guy. He says, 'Oh we should be profitable every month.' Well, when you're in a startup, that's not the goal. The goal is to grow the brand. It's expected that you're going to have losses. You should go through a period where you're making investment in the future. That's what we've been doing. He doesn't get it. And he doesn't get it because he's an engineer and he's not here."

One year later, Andy Krafsur regained the position of chief executive officer of Spira Footwear after a judicial ruling by District Court Judge Linda Chew. Although he wouldn't have complete financial anonymity, he was just happy to be back.

"We've been so beat up this last year. We haven't had a lot of victories, frankly. So you lower your expectations. For us, this was unexpected. It was a nice Christmas present," he said.

In subsequent years, Spira earned 200 victories at smaller distance events throughout the country but never captured any major titles in New York, Boston or Chicago.

Although they had managed to challenge the status quo and directly established a precedent for spring technology in racing, Spira Footwear ended production of their products in 2016.

“We have had to close the business,” Andy Krafsur said. “We’re in the process of looking for a buyer. I will not have a role in management. It was a great product, and I have to tell you that seeing it go is very difficult. I always thought it was going to take off – to the very end,” he said. “I never thought it wasn’t going to make it. We just ran out of money and runway.”

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