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Posted: May 26, 2005

Athletics: FREE to Run

By Richard Haddad

One hot summer day in June 2002, senior researcher Jeff Pisciotta set up the Nike Sports Research Lab (NSRL) on a grassy soccer field. Twenty runners, ten men and ten women, taped pressure-measuring pedar insoles to their forty bare feet. Two high-speed cameras took timed images of each foot in motion, while timing gates insured a running velocity of 7:30 minutes per mile.

On that soccer field, Piscotta and the rest of Nike's Innovation kitchen measured what happens when you run barefoot on the grass. They learned that the foot performs at its highest levels when it is uncovered - when it is Free. After two years of work, the results of the experiment culminated in the Nike Free 5.0.

The shoe aims to take runners back to the feeling of running barefoot - to mimic that feeling and its benefits while providing the benefits of footwear, protection and traction that the foot cannot offer on its own. Its basic premise is that a barefoot runner strengthens his foot by using intrinsic muscles that he wouldn't normally use. When you support an area by cloaking it in supportive footwear, for instance, it gets weaker, but when you use it extensively, it gets stronger. Vin Lanana, former Stanford track coach, called this observation "common sense," claiming that athletes that train barefoot run faster and suffer fewer injuries.

Lanana trained his unshod runners on the plush grass of Stanford's golf course for over ten years. When Nike caught wind of this, its researchers asked him, "We send your team all kinds of running shoes, so why are your guys running barefoot on the grass?" Pisciotta said. And when New Zealand coaching legend Arthur Lydiard - who Pisciotta calls the "closest thing to Bill Bowerman" - told Nike that his athletes had been running barefoot as supplemental training for years, Nike decided that the idea was worth investigating.

Lanana's and Lydiard's methods (and their results) got Nike's Innovation Kitchen cooking. Nike looked at independent studies of barefoot populations in Africa and learned that those communities experienced minimal runner-type injuries. But it couldn't find any research done with athletes. After consulting the annals of biomechanics literature, Piscotta learned that nobody had ever studied the effects of running barefoot on grass. So the Kitchen, an arm of research and development that seeks out and cooks up new ideas, decided to do so itself. On that grassy soccer field in June 2002, Nike undertook the most comprehensive barefoot study in the industry. The study measured its barefoot runners' joint angles, motion, and underfoot pressures. And it found a unique biomechanical pattern, a pattern different than any that they'd measured or studied in the context of traditional athletic footwear.

The findings reveal that, unshod, the foot is like an airplane coming in for landing, with a more neutral foot-to-surface angle. When they are allowed to move freely, the toes flex and grip, creating muscle usage up through the rest of the body. Every heel contact produces an equal balance of pressure and spurs a lateral progression of pressure to spread equally through the metatarsal region to the toes. The result? Lift-off.

What does all this mean? It means that, unrestrained by footwear, the foot works naturally and efficiently to distribute the pressure of landing and launching. The cushioning provided by a shoe prevents these actions, so a traditional running shoe cannot mimic these effects.

In short, it means the foot works best when it's free. But it took Nike two years to get from that concept to the shoe that embodies it. To do so, Pisciotta said that he had to forget everything he knew about shoes. He had to flush traditional shoe concepts and ignore his previous knowledge about running, footwear, and biomechanics. Instead, with an open mind, Pisciotta focused on what he'd seen on the grassy soccer field.

From that data, his team of researchers and designers developed and tested prototypes of a new minimal shoe. For most shoes, Nike goes through two or three prototypes, but the Free required ten. They tested polyurethane and phylon outsoles, experimenting with anything they could think of to build a shoe that closely mimicked the bare foot - that would allow the foot to use its own natural motion to deliver strength to the rest of the body. They learned from existing shoes that, in traditional shoes, the midsole and outsole take control of the foot because of their rigidity. So, on their prototypes, they relieved that rigidity by cutting out the midsole and slicing up the upper.

This siping - the creation of cuts in the shoe - allow the foot to enjoy a full range of motion, but their creation represented a huge manufacturing challenge, Pisciotta said. The depths of every cut were engineered according to the findings of Nike's researchers and developers - the Free's designers didn't draw a single line without consulting Pisciotta and the NSRL. Each cut was precisely positioned to reflect information about the force pattern that the lab had measured and the foot's skeletal anatomy.

The cuts allow the foot to control the footwear. In traditional shoes, solid masses of material surround the foot, and this forces the foot to adapt to the footwear and the surface. The footwear is more in control than the foot. But in the Nike Free, the shoe is merely the vehicle: the foot is the driver. The Free is there to protect your feet so that the foot is the controlling factor. The Free is more stable than its developers originally suspected because it allows the runner's toes to spread and grab the ground. The Free allows your foot to do the stabilizing. The foot remains in control.

The upper and bottom unit act in complete harmony with the foot and with each other, and the strategically placed slices make a static material more dynamic. They make the shoe come alive with the foot, and the runner immediately perceives this difference.

Nike's manufacturers worked for months to develop molds and processes that could produce reproducible and accurate footwear in which each sipe was made consistently and precisely. But the end result - the Nike Free 5.0 - rendered all of this effort worthwhile. Pisciotta said that there is no aspect of the final product with which he is not satisfied.

And, more importantly, athletes' responses have been just as overwhelmingly positive. Coaches and athletes who have implemented the Free into their training regimen, even those who were initially skeptical about the concept, tell Nike that, since they started working out with the Free, they feel healthier and stronger and suffer less injuries.

So what can the Free do for you? Barefoot training produces stronger, healthier feet. Stronger feet produce stronger ankles, knees, and hips, all the way up the kinematic chain. The end result is improved athletic performance. But nature cannot be left totally on its own; "footwear brings something to the party," Pisciotta says. Most runners can't - or won't - just go out and start running barefoot. So the Free offers an access point at which to begin by giving runners the best of both worlds.

The beauty of the Free is that it allows your foot to reap the benefits that stem from barefoot training while simultaneously providing the benefits of traditional footwear: level cushioning, protection, and traction. Pisciotta calls this a "happy marriage" between footwear and the bare foot.

The Free's demarcation as a 5.0 reflects this marriage. Pisciotta envisioned a scale where the number 10 signified the most technically constructed products, and 1 represents your bare foot on the grass. The Free 5.0 falls at the exact midpoint of this continuum and reflects the achievement of a perfect balance between technical footwear and the bare foot. It aims to maintain the benefits that come with traditional and technical running footwear while emphasizing the biomechanical results that Pisciotta observed in his studies on the grass. As runners progressively condition and strengthen their feet, they'll be able to take better advantage of the benefits of barefoot training by moving into an even freer shoe that mimics the bare foot even more closely. With this in mind, Nike is unveiling the Free 4.0 next fall, and the 3.0 is in its developmental stages.

To call the Free a non-technical shoe is overly simple; paradoxically, technicality is required to simulate the feeling of barefoot running, and the Free is highly technical in its own way. But the Free is not supposed to criticize or replace traditional or technical footwear. In a marathon, for instance, "you still want to put on an Air Max," Pisciotta says. The Free is a conditioning shoe, a complimentary product that trains your foot and gives you added strength and flexibility benefits in competition. Pisciotta compares it to a jump rope or ankle weights - it's a training aid. Ankle weights can be great when you are training, but you don't wear them to a race. But Pisciotta notes that pro athletes have worn the Free in triathlons, for instance, emphasizing that the circumstances in which the Free should be worn are dependent on the individual runner's own condition and experience with the shoe.

As a training tool, the Free must be utilized correctly. There is an educational component to it, and towards this end, it comes with a suggested training program. When you begin any type of training program, you have to start slowly and progressively build up. When you start training for a marathon, you don't run twenty miles on the first day, and with the Free, Pisciotta suggests that you start slow by wearing it around the house at first. After the first day, your arches and muscles will feel sore because they aren't accustomed to being used. Each individual progresses according to their own anatomy and their body's biomechanics. Once you've eased into the Free, you're ready to start your training program, to exercise and strengthen your foot's intrinsic muscles.

Athletes have been running barefoot on the beach for years. Kenyan runners run barefoot as a way of life. At Stanford, former track coach Vin Lanana trained his unshod athletes on the plush grass of Stanford's golf course for ten years. With the Nike Free, Nike offers the benefits of barefoot training to every runner - even those that don't live in Kenya, on a beach or near a golf course. With the Nike Free, you get all the benefits, but you can do it anywhere, anytime. The Free combines those benefits with the advantages offered by traditional footwear. It signifies a happy marriage of technology and nature, between footwear and the bare foot. It represents a new paradigm.

Richard Haddad is a running freak! Since 1989 he has been sighted at numerous marathons braving the 26.2 miles without the comfort and aid of shoes. A veteran of distance running and sheer lunacy, Richard has completed more than a half century of marathons and has started the New Year off right several times by finishing in the Top 10 for his age group. To learn more about his seanery tactics, Richard can be reached at

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© Copyright 2004 Peak Running Performance. All Rights Reserved. Reprinted with permission

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