Page 116 - Journal of Special Operations Medicine - Winter 2015

Administration, Nike developed an air-cushioned shoe Figure 2 Footprints used prior to 2007 to determine the type
called the Tailwind, in 1979 (Figure 1G). 4,5,7 of running shoe to purchase. (A) A high arch, for which a
cushioned shoe was recommended. (B) A low arch, for which
Figure 1 Running shoes across the ages: (A) Foster Spiked a motion control shoe was recommended. (C) A normal arch,
Plimsoll; (B) Keds (lower shoes advertised for tennis and for which a stability shoe was recommended.
sailing); (C) Converse All Stars; (D) New Balance Trackster;
(E) Onitsuka Tiger; (F) Nike Waffle; (G) Nike Tailwind; and
(H) Nike Air Max.

more durable but heavier and harder than EVA. Some
shoes, like the New Balance 520, New Balance 996, and
Kangaroo Omicoil, used EVA encapsulated in polyure-
thane in an effort to use the advantages of both materials.
Modern conventional running shoes are highly cushioned
in the heel and the forefoot, as shown in Figure 1H. 18,25,26

In the spring of 2004, Nike began selling the Nike Free
5.0, one of the first minimalist running shoes. In 2005,
27
Beginning in the late 1980s and into the 2000s, many Vibram Company began manufacturing and marketing the
running shoe companies began marketing three types Vibram FiveFingers, a shoe that had slots for the individual
of running shoes designed for runners who had dif- toes and had minimal cushioning. The FiveFingers idea
ferent foot arch heights. The assumption was that this was originally developed by Italian designer Robert Fliri,
could assist in selecting individually appropriate types who wanted a more “natural” shoe for outdoor activi-
of running shoes that could reduce the likelihood of in- ties. In 2009, Christopher McDougall published a rather
28
juries. 15–22 People with footprints reflecting low arches hyperbolic and humorous book entitled Born To Run.
3
(Figure 2A) were presumed to have greater rearfoot and McDougall provided stories of “Barefoot Ted,” who ran
midfoot mobility that allowed the foot to pronate (i.e., ultramarathons without footwear and of the Tarahumara
roll inward to the center of the body) excessively when Indians, a tribe of long-distance runners in New Mexico
the foot contacted the ground. “Motion control” shoes who ran only in sandals. In the course of the book, McDou-
were recommended for these individuals because it was gall argued that despite all the technological innovations,
assumed that these shoes could control the excessive modern running shoes have not reduced the incidence of
motion. Those with footprints reflecting high arches injuries and that barefoot running or the use of minimal-
(Figure 2B) were assumed to have rigid or inflexible feet ist footwear, as achieved by Barefoot Ted and the Tarahu-
that impacted the ground with greater force and did not mara, might be a better alternative. Because the Nike Free
pronate enough. These individuals were directed to- and Vibram FiveFingers were already available, they had a
ward cushioned shoes, which presumably allowed more bit of a jump in the minimalist market. Other shoe compa-
pronation and had greater cushioning to soften ground nies were quick to follow and produced lightweight shoes,
impacts. People with footprints reflecting normal arch some with cushioning and some without, that had a low
heights (Figure 2C) were assumed to impact the ground heel relative to the toe drop compared with conventional
with less force and have an appropriate amount of pro- shoes. A selection of minimalist footwear produced by a
nation on ground impact. A “stability” shoe, which was number of running shoe companies is shown in Figure 3.
presumed to have moderate cushioning and motion con-
trol characteristics, was recommended for them. 23,24 It is likely that running footwear will continue to evolve.
Since at least the mid 1970s, many shoe companies have
Motion control, cushioned, and stability shoes were established research and development facilities manned
manufactured by manipulating the density, amount, and by knowledgeable physiologists, podiatrists, engineers,
location of EVA or polyurethane in the midsole of the marketers, and other professionals. Whether the move-
shoe. EVA was lighter and provided more cushioning but ment will continue toward minimalist footwear or in
tended to breakdown and lose its shock absorbing prop- another direction cannot be reasonably determined.
erties more rapidly than polyurethane. Polyurethane was However, there is little doubt that running will continue

104 Journal of Special Operations Medicine Volume 15, Edition 4/Winter 2015