Free

An unexpected discovery

In the early 2000s, barefoot running, which had always been a niche element of the wider running community, was slowly increasing in popularity. At the same time, Nike was learning that its popular running shoes weren’t as good as they necessarily could be. During a conversation with expert coach Vin Lananna, Tobie Hatfield, Director of Athlete Innovation at Nike, made an unexpected discovery. Lananna had co-founded the Nike Farm Team to support Stanford’s post-collegiate distance runners, and Hatfield wanted to learn just how the trainer’s athletes became such good runners. To his surprise, he was told that part of the secret was that they took Nike’s shoes off when they ran. This comment sent the brand on a journey into the world of barefoot running, bringing about a new form of shoe technology known as Nike Free. 

Breaking new ground

Following Lananna’s shock revelation, Hatfield went to work alongside Eric Avar, VP of Creative Innovation, to find out how they could improve Nike’s offerings in the running department. The first thing they found was that there was little information available on the science of barefoot running, so they decided to do their own research, which turned out to be quite pioneering at the time. They enlisted Jeff Pisciotta, Director of the Nike Sports Research Lab, to carry out tests on Stanford’s runners, both male and female, as they ran on the university’s golf course. To focus on the foot, he set up a series of experiments using high-speed cameras combined with special insoles and other sensors to measure exactly how the muscles and tendons moved during barefoot running. He recorded the different pressure points of the foot and the forces acting upon it as it impacted the floor, as well as the angles of the joints when in motion. This gave Pisciotta a very clear picture of the precise movements and positions of the foot as it transitioned through its full range of motion. 

Barefoot insights

What this research showed Hatfield and his team was that the foot behaved very differently when clad in a shoe than when the runner moved around barefoot. It contacted the ground at a flatter, more neutral angle, using a more complete range of motion through the ball of the foot and the toes, which clutched onto the ground a little before fanning out as they pushed off, only leaving contact with the ground when the rest of the foot was almost perpendicular to it. Traditional running shoes aimed to protect and support the foot during this process, but, in doing so, they restricted this motion, meaning that many of its muscles did not get used or exercised. With these insights in hand, Nike set out to create a runner which would free up the foot to move in a more natural way that was closer to barefoot running while also protecting it from potential hazards that might be come across when running in the city.

A flexible technology

Pisciotta, Hatfield and Avar worked together to build a shoe which gave the foot more control over each step. To do so, they used a process called siping, which had been invented in the early 1920s as a way to stop car tyres and shoes from slipping in wet conditions. It consists of cutting extremely thin slits into the sole which, while providing traction, also releases any rigidity in the material, making it tremendously flexible in the process. Reverse flex grooves were added under the toes, which set the Nike Free apart from other running shoes as it freed the digits up to flex, grip and extend when they needed to. This facilitated a far more natural running motion that was much closer to barefoot running than the brand’s other models. 

The design process involved constant trial and error, with small alterations being made each time to see what worked best. In the end, this meant that the engineering was incredibly fine-tuned as the team adjusted the depth of the sipes by millimetres at a time until they found the ideal construction. Along with this, they gave the Free a more balanced gradient from heel to toe, a 33-degree toe-off angle (the angle as the foot rises from the floor during the step) and a flatter pronation pattern that was aimed at creating a more natural side-to-side movement throughout the step to prevent the foot rolling too far one way or the other and causing injury. As well as making the sole as flexible as possible, Hatfield and Avar were keen to use a minimal setup throughout, with lightweight, stretchy, breathable materials across the upper that conformed to the foot and shifted along with its natural movement. All these elements combined to make the Nike Free feel more like an extension of the foot than a running shoe.

The Free Scale

The first Free model, the Nike Free 5.0 V1, was released in 2004, three years after Hatfield’s pivotal conversation with Lananna. It had the flexible, siped sole, which was low to the ground for that barefoot feeling, a traditional lacing system and, unlike other barefoot running shoes, no individual toe formations. It also featured a skeleton graphic of the bones of the foot across the insole to represent Nike’s focus on anatomy in its design. The number 5.0 was significant as well. It showed how close the experience of running in the shoe was to running barefoot by representing a position on the “Free Scale” or, as Pisciotta called it, the “Free Continuum”. Either way, the concept was simple – the scale went from 0.0 to 10.0, with the lowest score denoting fully barefoot and the highest score indicating a heavily padded shoe. The first Free running shoe was set right in the middle, suggesting that it was halfway between traditional runners and completely barefoot running, so it could be used as a compromise between the two. Nike has since played around with this numbering system, changing it for the release of the Nike Free RN in 2016. Up until 2019, when the numbering system was reintroduced, all Free shoes were simply given the RN name, with no number to indicate the level of cushioning.  

Constant development

Since its launch in 2004, Nike’s Free technology has undergone many alterations along the way. In the years directly after the Nike Free 5.0 V1 came out, newer versions were made with different materials that enhanced comfort, flexibility, durability or all three, such as the BRS 1000 carbon rubber outsole and Phylite midsole that were added to the V3 in 2007. These models were always sold as good options for those who were working to strengthen their feet and improve their natural gait. In 2008, the Nike Free 3.0 became the lowest shoe on the scale to date. It was designed to be ultra-lightweight as well, with a slim, two-panel mesh upper replacing the previous fabric overlays. Two years later, the V2 of the Free 3.0 had a one-piece mesh upper with no-sew overlays for the most barefoot feeling possible.

The barefoot running experience

As 2009 came around, Nike found themselves on the crest of a wave. American author and journalist Christopher McDougall released his popular barefoot running book, Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen, which suggested that modern padded shoes led to more running injuries. In his research for the book, he spent time with a Native Mexican tribe who regularly ran huge distances in thin sandals without sustaining any injuries. These people were in excellent physical shape, and their story inspired McDougall’s writing. The book sparked something within the running community, leading to a proliferation of barefoot runners and the establishment of the Barefoot Runners Society in the United States. One year later, the New York City Marathon had more barefoot runners than ever before. Nike made the most of this period, releasing V4 of the Free 5.0 in 2009 as the perfect transitional shoe between traditional running and barefoot. The brand encouraged people to make this move, suggesting that running barefoot, or at least closer to it, could help to build stronger feet as those tendons and muscles which had previously been neglected in sturdier footwear could now be exercised again. With the help of Nike Free, runners could vary the training delivered to their feet and legs while still getting a modicum of support underfoot.

Not just a runner

Throughout the 2000s and beyond, Free models were released for other purposes as well, such as a cross training shoe called the Nike Free Sparq. A women’s model came in 2011 – the Women’s Free TR Fit 2. Made with triangular sipe patterns in the sole, it aided multidirectional movement, making it appropriate for a range of workouts. Around the same time, the Nike Free Walk+ offered the public a comfortable shoe to walk in, and the Nike Free Gym+ was aimed at yoga enthusiasts. 

In 2012, the Nike Free Run 2 saw the technology get more of a boost in the fashion market. Mark Miner, Senior Footwear Designer at Nike, had focused on creating great performance shoes in his Free Run+ series, but his use of colour blocking to highlight the new performance elements that were added to each design led to some captivating and iconic models that were favoured as fashion items as well as running shoes. At the same time, the Nike Free was beginning to attract high-profile collaborations such as one with Tiger Woods, whose signature Tiger Woods ‘13 brought the Free to golfers. The skating world also got access to Free technology in 2018, when it was fitted onto the sole of skater Nyjah Huston’s collaboration, the Nike SB Nyjah Free. This sparked a series of Nyjah releases, whose use of Nike Free is a great innovation in the skating community. 

A natural feeling

Throughout the history of Free technology, Nike’s designers have continued to work with runners at all levels, from collegiate sports to Olympic athletes, to test new ideas, but the inspiration has only ever been one thing – the natural movement of the foot during running. Through its Innovation Kitchen, Nike looked at how the foot functions in more and more detail, with each new Free design having to go through a rigorous testing process to make sure that the tech fits the name. The flex grooves have always been an integral part of the design, undergoing repeated testing to make sure that they are in the best position and at the best depth. As well as the sipes running across and up the sole, newer models have featured a hexagonal sipe pattern to provide better multi-directional movement. Trans-tarsal flex grooves were added for the first time in 2012, improving the barefoot feeling, while the 3.0 versions contain more sipes for the ultimate in flexibility. However the sipes appear, they have to compliment each other across the whole length of the sole to facilitate natural movement of the entire foot. The Free has also been combined with some of Nike’s other technologies over the years, from Zoom cushioning to Flyknit material on the upper and a Flywire lacing system. These last two technologies are ideal additions to the Free, giving it even more flexibility for that authentic natural feeling. Free technology has even made its way onto other Nike designs, such as the Metcon. Beginning on the Nike Free x Metcon and later appearing on the Nike Free Metcon 4, narrow sipes in the forefoot helped this stable training model to provide more flexibility and ease of movement through the front part of the shoe, further adding to its diverse applications. 

The foot liberated

Nike Free technology began with a simple conversation that kindled an idea in the minds of the brand’s top designers. For many years, the focus had been on supporting and protecting the foot, but with the Free, this completely changed, taking the runner back to something more liberating. With incredible attention to detail, the line has evolved to move in harmony with the various muscles and tendons of the foot – to feel like part of it. In reducing the protective padding, runners can re-engage underused muscles and joints to experience the joy of running barefoot whilst still getting the protection they need. With every iteration, Nike Free takes us ever closer to the ultimate feeling of running barefoot.