An international team of researchers suggests that running barefoot may be better for the feet and joints of the lower limbs because they found people who run barefoot or in minimal shoes strike their foot on the ground in such a way that they have almost no impact collision due to “heel-strike”, unlike people who run in modern running shoes where the impact of the more prevalent heel-strike can be the equivalent of landing with two to three times of one’s body weight.

Dr Daniel E. Lieberman, a professor in Harvard University’s new department of human evolutionary biology in Cambridge, Massachusetts, US, and colleagues, have written a paper about their findings the 28 January online issue of Nature.

Lieberman and colleagues found that barefoot endurance runners tended to land on the forefoot (the ball of the foot) before bringing down their heel, or they landed on the middle part of the foot, and very rarely landed on the heel. But runners who wore running shoes tended to land on the rear foot, “facilitated by the elevated and cushioned heel of the modern running shoe”.

They also found that by landing on the front or middle of the foot, the barefoot runners used the architecture of the foot and leg to avoid potentially damaging and painful impacts of “heel-strikes”, which causes runners repeatedly to hit the ground with the equivalent of two or three times their body weight.

Lieberman told the press that:

“People who don’t wear shoes when they run have an astonishingly different strike.”

“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,” he added.

Although humans have been running for millions of years, specialized shoes designed for running were only invented in the 1970s, wrote the authors in their background information. Before that, people either ran barefoot or with minimal footwear, for instance moccasins or sandals, which have smaller heels and hardly any cushioning compared to the running shoes we can buy in the shops today.

The study came about because Lieberman and colleagues wondered how people coped with the impact caused by the foot hitting the ground before the modern shoe was available.

Lieberman explained:

“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,” said Lieberman.

For the study, Lieberman and his colleagues at Harvard, the University of Glasgow in the UK, and Moi University in Kenya worked with runners in the US and Kenya.

They used what they described as “kinematic and kinetic analyses”, which enabled them to observe movements of runners’ bodies (their “running gait”) in space (kinematics) and the forces involved in producing the movements (kinetics). Such analysis demands a good understanding of Newtonian physics and applied mathematics, as well as knowledge about the human body and biomechanics, except in this study it was also informed by evolutionary medicine.

The researchers examined the running gait of three types of runner: those who had always run barefoot, those who had always worn shoes, and those who used to wear shoes but had converted to barefoot running; and found a remarkable pattern of differences.

The running pattern of most shod runners, more than 75 per cent of Americans, showed a distinctive “heel-strike” with a large and sudden collision force occurring about 1,000 times per mile of running. But the runners who ran barefoot tended to land with a springy step toward the middle or the front of the foot.

The researchers concluded that:

“Fore-foot- and mid-foot-strike gaits were probably more common when humans ran barefoot or in minimal shoes, and may protect the feet and lower limbs from some of the impact-related injuries now experienced by a high percentage of runners.”

Co-author Dr Madhusudhan Venkadesan, a postdoctoral researcher in applied mathematics and human evolutionary biology at Harvard, said:

“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.”

“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,” he added.

The researchers suggest there is an evolutionary explanation for the differences between running barefoot and running with shoes.

The arches in the feet of our early Australopith ancestors were less developed, while Homo sapiens, by contrast, has evolved a strong, large arch that acts like a spring when we run, as Lieberman explained, “our feet were made in part for running”.

However, they do not suggest shod runners should get rid of their shoes and become barefoot runners overnight. Modern humans have grown up wearing shoes, and barefoot or minimal shoe running is something to be eased into, warned Lieberman.

Modern running shoes are designed to cushion the impact of heel-striking and make it easy and comfortable, and less punishing.

“Running barefoot or in minimal shoes is fun but uses different muscles,” said 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,” he explained.

The team hopes to build on their findings and do more investigations into running, such as how to prevent the repetitive strain injuries suffered by a high proportion of today’s runners.

Lieberman said they hoped that:

“An evolutionary medicine approach to running and sports injury can help people run better for longer and feel better while they do it.”

To this end, he and his colleagues have started a website called Running Barefoot or in Minimal Footwear to provide runners with an “evidence-based resource” for understanding more about the pros and cons of running barefoot or with minimal footwear.

The study was funded by grants from the American School of Prehistoric Research, the Goelet Fund, Harvard University, and Vibram USA.

“Foot strike patterns and collision forces in habitually barefoot versus shod runners.”
Daniel E. Lieberman, Madhusudhan Venkadesan, William A. Werbel, Adam I. Daoud, Susan D’Andrea, Irene S. Davis, Robert Ojiambo Mang’Eni & Yannis Pitsiladis
Nature, 463, 531 -535 (28 January 2010).

Source: Harvard Science.

Written by: Catharine Paddock, PhD