The work on toe springs is described in Scientific Reports. The researchers say this potential weakness could make people more susceptible to medical conditions like plantar fasciitis — a common, hard to repair, and painful inflammation of the thick, web-like band of tissue that connects the heel bone to the toes.
In our research, we were interested in a nearly ubiquitous element of modern shoes that has not been studied before: the upward curvature at the front of the shoe.
He means the toe spring, of course, which constantly flexes the toe box above ground and is a feature of most modern footwear, especially athletic shoes. The project started after Sichting and Lieberman met at a conference in Boston, and of course went for a run by the Charles River, during which they talked about foot biomechanics and plantar fasciitis. In the experiment, 13 participants walked barefoot and in four pairs of custom-made sandals on a specially designed treadmill equipped with force plates and an infrared camera system to measure how much power is put into each step.
The sandals each had varying degrees of toe spring angles — from 10 degrees to 40 degrees. They were designed to mimic the stiffness and shape found in commercially available shoes. The more curved a toe spring is, the less power the foot inside the shoe has to exert when pushing off from the ground while walking. MTP joints are one of the key features that have evolved so that humans can walk and run on two feet so effectively and efficiently.
Thus, habitually wearing shoes with toe springs could inhibit or de-condition the force-generating capacity of intrinsic foot muscles.
A groundbreaking researcher in running turns his attention to walking, with and without shoes. The researchers make clear in the paper that more research is needed on all fronts and that their study does not directly link toe springs with plantar fasciitis or other common foot problems.
The study also included only habitual shoe users whose feet may already have been adapted to shoes with toe springs. This could give us a more complete picture of how shoes affect our biomechanics. Still, they say the unrecognized biomechanical effects of toe springs on foot function merit further consideration. In his new book Joe Henrich looks at how the West became psychologically peculiar and prosperous.
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.
Lieberman, professor of human evolutionary biology at Harvard University and co-author of a paper appearing this week in the journal Nature. 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, times per mile run.
People who run barefoot, however, tend to land with a springy step towards the middle or front of the foot. 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.
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 s. 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. 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. The Nature paper arose out of the senior honors theses of two Harvard undergraduates, William A.
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