Our Own Devices: How Technology Remakes Humanity (16 page)

Athletic-shoe making could now attract talent from other professions. Tinker Hatfield became Nike’s vice president of design and special projects in 1984, three years after joining the company as architect of its display
rooms. A former college athlete with no previous shoe
industry experience, Hatfield specialized not only in collaborating with outstanding sports figures but in introducing motifs from popular culture. Working with Michael Jordan, he designed the original Air Jordans in 1985. They were inspired by the fiery nose ornamentation of World War II bombers. Jordan’s 1990s shoes included jagged Afro-Pop designs with what Hatfield called “an aggressive caricaturelike
quality.” Hatfield also has claimed inspiration from Mighty Mouse cartoons (for their affinity with footballer Bo Jackson), Native American moccasins, and more recently automobile styling. And the sneaker industry was one of the first to turn to nature for design ideas. In the 1980s, Nike sponsored research by a zoologist, Ned Frederick, who had written his doctoral thesis on the musculature
of the striped skunk’s feet. Frederick became Nike’s research director in the early 1980s. Years later in England, the first prize of a 1998 Royal Society of Arts contest to design an ideal running shoe went to a transport designer at Coventry University who was inspired by animal footprints to equip his model with small claws for a better grip in wet weather. Reebok hired him.
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The new materials
were made not only to perform—the athletic endorsers of Nike and other companies needed, after all, to win in them— but to dramatize performance. Color television and especially cable continued the process that had begun with the 1954 World Cup. Thanks to television and to new design and manufacturing techniques and materials, the shoe itself could now tell a story not just to a few close-up
spectators but to national and international audiences. As Hatfield explained: “When Michael comes down the court, we want you to see him coming—in shoes that you recognize from a hundred yards. That is the philosophy behind the Air line.” Strong design told a story to the all-important retailer as well as the consumer. And as dramatists, shoe designers assumed some of the aura of film directors.
Tinker Hatfield became a world celebrity in his own right. In 1997, Reebok featured its own director of research engineering, Spencer White, as “The DMX™ Design Guy” in national television advertising with Shaquille o’Neal among others, and even as a full-length cardboard retail display figure.
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The shimmering textures of the contemporary running shoe, essential as they are to marketing,
are intended by makers and buyers alike as only the
outward expressions of a complex technological product. The focus of athletic-shoe development for the last twenty-five years has been largely elsewhere: in the midsole region, which once did not even exist. Rarely has so much money been invested for so long in a space of a few cubic centimeters in an item of apparel.

The midsole grew in importance
in the 1970s, as biologists, physicians, and sports scientists began to pay greater attention to the physics of running. One of their first surprises was the cost of wearing any shoes— the price in energy, that is, not in dollars. Peter Cavanagh has observed that the typical running shoe not only makes the foot 25 percent heavier but also adds that weight at the rapidly moving point where
the body needs the most energy. A few noted athletes have been able to profit from the savings. The record-breaking English track star and biologist Bruce Tulloh, who wrote the British best-seller on recreational running, raced barefoot while still a university student and thereafter competed brilliantly with nothing more on his feet than adhesive bandage wrapped around the big toes. Griffiths Pugh,
a physiologist, measured Tulloh’s shod and unshod performance and found that wearing footwear while running requires between 1 and 2 percent more energy than running barefoot, an immense margin for any elite athlete. Thanks to an exceptional light but rugged build and meticulous planning, Tulloh had run 3,500 miles without injury by the late 1970s. Meanwhile, the Ethiopian Abebe Bikila, who normally
ran in shoes, electrified the 1960 Rome Olympics by discarding them when they became uncomfortable and winning the marathon event barefoot. In 1985, the South African—born Zola Budd, running barefoot, established a record for the 5,000-meter race. Even two NFL placekickers, Tony Franklin and Rich Karlis, have performed without shoes. While few other athletes can forgo protection, the dissenters
found support in the late 1980s in research by R. McNeill Alexander, a biomechanics pioneer. The biologists Giovanni Cavagna and Rodolfo Margaria had already shown that runners move by storing and releasing elastic strain energy, like bouncing balls. Alexander found that the tendon returns 93 percent of its energy as it recoils and the arch about 78 percent. The midsoles of the running shoes he
tested, including most of the leading brands, returned between 55 and 65 percent of the energy needed to deform them.
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While the foot theoretically remains the ultimate running technology, shoes are still a must. Since high-performance surfaces for conventional running, “tuned tracks,” exist, it should be feasible to design one especially for use without shoes. But because many surfaces are
unfriendly to the
foot, it is the midsole that absorbs much of the stress of hitting the ground. Each time we touch down while running, our feet sustain an impact as though we were taking a step with two grown people sitting on our back, in Peter Cavanagh’s metaphor. A 150-pound man sustains a half-million pounds of pressure in a mile. Fortunately the flexing of the knees and the stretching of
the gluteus, hip, and ankle muscles dissipate most of this shock. But especially as millions of people around the world began to run for health in the late 1970s, running-shoe makers began trying to assist this natural cushioning. This is not as simple as it seemed to the late-nineteenth-century shoemaker who offered springs as an option. If the knee does not flex enough, harmful forces may be transmitted
to bones and muscles. Human feet and legs form a complex system with many possible interactions of parts and running surfaces.
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The breakthrough in midsoles came in 1975, when Brooks Shoe Company introduced a shoe called the Villanova with a midsole and heel wedge made of ethylene vinyl acetate (EVA). This polymer, which we have already encountered as a sandal material, had been developed by
a chemical engineer, David J. Schwaber, at the Monarch Rubber Company of Baltimore, a major aerospace contractor. While natural and synthetic rubber can also be made elastic by using a blowing agent to fill the product with bubbles, EVA offered an excellent combination of light weight and resilience; soon it displaced rubber. In five years in the mid to late 1970s, midsole foams lost three-quarters
of their weight. EVA has helped runners go longer distances with fewer injuries, but it has also shortened the useful lives of many shoes. It goes flat like sparkling water and champagne, although with use rather than time. Soft EVA provides excellent cushioning at the cost of some stability, but it also loses its shock absorbency, becoming (in the words of one manufacturer’s spokesman) “almost
a hard plastic.” Firmer EVA degrades more slowly and provides more stability, but also affords less protection against injuries. Polyurethane, the major alternative and complement to EVA, lasts longer but does not offer the same cushioning and may be half again as dense.
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The 1980s were the great decade of the midsole, with a profusion of exotic shapes and materials. A series of cushioning systems
transformed the athletic-shoe market again. Heavier but more durable than EVA and polyurethane, these systems did not completely eliminate the old materials, but they did absorb impact more effectively and helped the shoe last longer. The most famous and commercially successful was Nike’s Air. Air bags in footwear are an old idea; about 150 patents were filed between
1882 and 1970. Until the 1970s,
none was satisfactory. Because of the very forces that make cushioning so desirable, the air leaked and the shoes went flat. Just as architects began literally revamping shoe uppers, engineers were breathing life into the midsoles. Frank Rudy, who had resigned a senior aerospace technology management position in 1969, codeveloped a liner for ski boots and applied a similar principle to a polyurethane
film sac that transferred gas among compartments to cushion athletes’ movements. Diffusion pumping, as he and his coinventor Bob Bogert called it, shifted material more efficiently than alternative cushions and springs. Of several companies that offered the invention, only Nike saw beyond its earlier failures, developing a flexible but nonleaking air liner and finding gases with molecules
that, unlike common air, would not be forced out. (When the Tailwinds started to fail in 1979, consumers erroneously thought the air compartments had deflated, probably misinterpreting the expression “blowout,” shoe manufacturers’ slang for falling apart. Later metallic finishes created no such problems.) As a rookie with the Chicago Bulls in 1984, Michael Jordan linked the red-and-black Air shoe
with legendary jump shots that made it the most rapidly profitable and influential patented technology in the history of sports, vindicating Nike’s record-shattering $2.5 million contract with the player. As important as Jordan’s endorsement was Nike’s development of “Visible Air” models, including the Air Max, that made the gas-filled chambers visible through the sides of the shoes. These made
it easy to explain the system to the sales force, retailers, and consumers. The “Visible Air” principle worked as the picture windows in American car washes and translucent Macintosh computer cases do, selling a process by turning it into theater. In their first six years, sales of the fifty-odd models of Air shoes exceeded $2 billion and helped Nike increase its market share to 36 percent.
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Not everybody applauded. Surprisingly, there are no published tests of the durability of air inserts, but one orthopedist has estimated they extend a shoe’s life by a quarter to a half. (
Runner’s World
magazine still notes the insert can deflate.) The original Rudy patents expired in 1997, but meanwhile other makers had developed their own midsole systems: Reebok’s Pump (user-inflatable air bladder)
and Hexalite (thermoplastic honeycomb created by the aerospace company Hexcel), ASICS Tigers’ gel (silicone), Brooks’s Hydroflow (liquid silicone—filled, featuring a dual-chambered heel), Etonic’s Stable Air (encapsulated air), and Puma’s and Adidas’s synthetic gels. A company called KangaROOS USA introduced a resilient midsole with a NASA-developed material called Dynacoil in 1985.

There are
other ways to control the properties of shoes. The inner heel can be reinforced to combat that ubiquitous source of running discomfort and injuries, overpronation, the tendency to roll the foot excessively inward after initial contact. Some shoes have composite roll bars for stability.
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Both the weakness and the strength of running-shoe research has been that none of these approaches, even the
Nike Air system, has displaced the others. There are so many variations of human legs, feet, running, and walking styles, and so many surfaces and conditions, that
Runner’s World
long ago abandoned its early system of ranking shoes according to scientific tests. While models fall into a number of types for overpronators and supinators (runners who turn their feet outward), each buyer—whether athletic
or casual—has to search for the right match. Some brands use straight lasts, others curved “banana” lasts. The difference is palpable. And a shoe that feels comfortable in a showroom may be painful after actual exercise. Because of all the variables in real-world conditions, laboratory tests also have limited value. The Tailwind seemed to offer impressive gains in efficiency, yet no elite
runners were able to improve their times with that model. The genius of the industry has been not any single invention but the variety of equipment to suit not only the techniques of different sports but the bodies and running styles of so many people. Without this diversity, far fewer people would have been able to run competitively. Many more would have given up after injuries.
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By the late 1990s the logic of running shoe development was under strain. Thanks to CAD/CAM, short development cycles were flooding the market with new models. By early 1997, Nike designers were producing up to four new shoe models each year, introduced seasonally, for a total of more than eight hundred new designs annually, more than three for every business day. Obviously these numbers
would have been unthinkable before computerized logistics for coordinating international shipment of parts and materials and advanced systems for tracking sales and inventories. While sneaker publicity had become ubiquitous in popular culture, it was for that very reason extremely expensive; according to a
Washington Post
investigative article in 1995, the $70.00 price of a pair of Nike Air Pegasus
shoes included $4.00 for advertising, 16 times the $0.25 research and development costs. Even with features readily visible and identifiable, consumers could be easily confused, and only a limited number of
specialist retailers could give buyers useful advice. The search for optimal fit and performance could make shopping Sisyphean, as even recent models were discontinued to make way for yet newer
ones. And the prices of the most coveted models remained daunting. A high-performance running shoe selling for $140.00 has a useful life of 300 to 500 miles, according to shoe experts. Accepting 400 miles, the cost per mile would be $0.35, more than the $0.325 allowed by the U.S. Internal Revenue Service in 1999 for automobile use as a business expense, which includes not only tire wear but depreciation,
insurance, fuel, motor oil, and maintenance.
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The sport shoe market began to mature in the early 1990s. After more than doubling in the 1980s, to reach 384.2 million pairs in 1990, unit sales fluctuated in the 1990s. According to the Athletic Footwear Association (AFA), U.S. sales were 325.4 million pairs in 1998, barely more than the 325.1 million pairs recorded in 1994, though dollar volume
had grown from $11.66 million to $13.8 billion because prices had crept up by about 3 percent annually. Still, between 1997 and 1998, the market declined by 6 percent. The AFA’s report found signs of hope but also noted “more stores with more space for more shoes than consumers want” as a big problem. By the end of 1999, one American athletic-shoe chain was preparing to close more than a quarter
of its 236 outlets in a bankruptcy reorganization, and the big sneaker manufacturers were pledging expanded advertising budgets to help the sporting goods chains.
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