Barefoot Running: Humans Ran Comfortably
and Safely Before the Invention of Shoes
New research is casting doubt on the old adage, "All you need
to run is a pair of shoes."
Scientists have found that those who run barefoot, or in minimal
footwear, tend to avoid "heel-striking," and instead
land on the ball of the foot or the middle of the foot. In so
doing, these runners use the architecture of the foot and leg
and some clever Newtonian physics to avoid hurtful and potentially
damaging impacts, equivalent to two to three times body weight,
that shod heel-strikers repeatedly experience.
"People who don't wear shoes when they run have an astonishingly
different strike," says Daniel E. Lieberman, professor of
human evolutionary biology at Harvard University and co-author
of a paper appearing this week in the journal Nature. "By
landing on the middle or front of the foot, barefoot runners have
almost no impact collision, much less than most shod runners generate
when they heel-strike. Most people today think barefoot running
is dangerous and hurts, but actually you can run barefoot on the
world's hardest surfaces without the slightest discomfort and
pain. All you need is a few calluses to avoid roughing up the
skin of the foot. Further, it might be less injurious than the
way some people run in shoes."
Working with populations of runners in the United States and
Kenya, Lieberman and his colleagues at Harvard, the University
of Glasgow, and Moi University looked at the running gaits of
three groups: those who had always run barefoot, those who had
always worn shoes, and those who had converted to barefoot running
from shod running. The researchers found a striking pattern.
Most shod runners -- more than 75 percent of Americans -- heel-strike,
experiencing a very large and sudden collision force about 1,000
times per mile run. People who run barefoot, however, tend to
land with a springy step towards the middle or front of the foot.
"Heel-striking is painful when barefoot or in minimal shoes
because it causes a large collisional force each time a foot lands
on the ground," says co-author Madhusudhan Venkadesan, a
postdoctoral researcher in applied mathematics and human evolutionary
biology at Harvard. "Barefoot runners point their toes more
at landing, avoiding this collision by decreasing the effective
mass of the foot that comes to a sudden stop when you land, and
by having a more compliant, or springy, leg."
The differences between shod and unshod running have evolutionary
underpinnings. For example, says Lieberman, our early Australopith
ancestors had less developed arches in their feet. Homo sapiens,
by contrast, has evolved a strong, large arch that we use as a
spring when running.
"Our feet were made in part for running," Lieberman
says. But as he and his co-authors write in Nature: "Humans
have engaged in endurance running for millions of years, but the
modern running shoe was not invented until the 1970s. For most
of human evolutionary history, runners were either barefoot or
wore minimal footwear such as sandals or moccasins with smaller
heels and little cushioning."
For modern humans who have grown up wearing shoes, barefoot or
minimal shoe running is something to be eased into, warns Lieberman.
Modern running shoes are designed to make heel-striking easy and
comfortable. The padded heel cushions the force of the impact,
making heel-striking less punishing.
"Running barefoot or in minimal shoes is fun but uses different
muscles," says Lieberman. "If you've been a heel-striker
all your life you have to transition slowly to build strength
in your calf and foot muscles."
In the future, he hopes, the kind of work done in this paper
can not only investigate barefoot running, but can provide insight
into how to better prevent the repetitive stress injuries that
afflict a high percentage of runners today.
"Our hope is that an evolutionary medicine approach to running
and sports injury can help people run better for longer and feel
better while they do it," says Lieberman, who has created
a web site, www.barefootrunning.fas.harvard.edu, to educate runners
about the respective merits of shod and barefoot running.
The Nature paper arose out of the senior honors theses of two
Harvard undergraduates, William A. Werbel '08 and Adam E. Daoud
'09, both of whom went to Africa with Lieberman to help collect
data for this study.
Lieberman's co-authors on the Nature paper are Venkadesan and
Daoud at Harvard; Werbel, now at the University of Michigan; Susan
D'Andrea of the Providence Veterans Affairs Medical Center in
Providence, R.I.; Irene S. Davis of the University of Delaware;
and Robert Ojiambo Mang'Eni and Yannis Pitsiladis of Moi University
in Kenya and the University of Glasgow in Scotland.
The research was funded by the American School of Prehistoric
Research, the Goelet Fund, Harvard University, and Vibram USA.
January 28, 2010