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					Runners, baring your soles makes you
well-heeled
By SETH BORENSTEIN - AP Science Writer

WASHINGTON -- Harvard biologist and runner Daniel Lieberman had a simple
question: "How did people run without shoes?"

The answer he got is: Much better.

At least running barefoot seems better for the feet, producing far less impact stress
compared to feet shod in fancy, expensive running shoes, according to a study by
Lieberman in Thursday's issue of the journal Nature. The study concludes that people
seem to be born to run - barefoot.

       Nature

The research was funded in part by a company that makes minimalist running shoes that
try to mimic barefoot running. But Lieberman, who disclosed the grant, said the company
had no say in the design of the study and didn't influence the outcome.

People who grew up running barefoot - such as boys in Kenya's Rift Valley province,
which is known for endurance running champs - tend to land mostly on the front or
middle of the foot when they touch ground. And when these runners do use shoes, they
continue to run in that way.

People who have always worn cushioned running shoes usually hit the ground heel first.

The difference in the way the foot strikes the ground is important. Lieberman's study
examined the physical stresses on feet with different types of running and found that
people with running shoes strike the ground with the mass of the entire leg, nearly 7
percent of the body. That's more than three times the weight of impact for barefoot
running.

"It's really about how you hit the ground," said Lieberman, who specializes in human
evolutionary biology. "When you hit the ground, some of your body comes to a dead
stop."

For runners in cushioned shoes, "it is literally like someone hitting you on the heel with a
hammer," Lieberman said. But, he said that "the way in which barefoot runners run is
more or less collision free."

But runners should be cautious about ditching their shoes or using new ones that mimic
barefoot running, Lieberman said. If you change the way you run quickly "you have a
high probability of injuring yourself," he said. In general, changes either in running shoes
or distance should be no more than 10 percent a week, he said.

The study doesn't look at injuries from running and doesn't conclude that shod runners
are injured more often. That specific research should be looked at next, he said.

Lieberman has looked at the evolution of long-distance running; 2 million years ago our
pre-human ancestors used that approach to wear out prey during prolonged hunts. He
found that the 1970s invention of the modern running shoe changed our strides. And it
wasn't necessarily for the best.

The study turned Lieberman into a barefoot-running convert, weather permitting.

"We did not evolve to run barefoot in New England in the winter," he said. Yet, he said
hard surfaces, glass, nails and concrete aren't a real problem for barefoot running. Acorns
are.

Dr. Pietro Tonino, chief of sports medicine at the Loyola University Health System in
Chicago, wasn't part of Lieberman's study but said it makes sense because of what he
sees every day.

"When you look at runners, the most common thing they have is, in most cases, heel
injuries," Tonino said. The No. 1 foot injury that Tonino sees is plantar fasciitis, a painful
irritation and swelling of the bottom of the heel.

Tonino said cushioned running shoes work against evolution which developed the foot
properly for endurance running.

"Your body is basically just very passive in the running activity compared to probably
what it was designed to do," Tonino said.

Tonino doesn't recommend barefoot running for Americans who have gotten used to
modern running shoes, but said for people who do not have foot injuries, less constrictive
shoes might be a good idea.

For his part, Lieberman said barefoot running "is a movement that ain't going away."

				
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posted:10/27/2011
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