The bare truth about shoes

New York Magazine has a very interesting article about shoes and how they are ruining our feet.

Are shoes ruining our feet?Last year, researchers at the University of the Witwatersrand in Johannesburg, South Africa, published a study titled “Shod Versus Unshod: The Emergence of Forefoot Pathology in Modern Humans?” in the podiatry journal The Foot. The study examined 180 modern humans from three different population groups (Sotho, Zulu, and European), comparing their feet to one another’s, as well as to the feet of 2,000-year-old skeletons. The researchers concluded that, prior to the invention of shoes, people had healthier feet. Among the modern subjects, the Zulu population, which often goes barefoot, had the healthiest feet while the Europeans—i.e., the habitual shoe-wearers—had the unhealthiest. One of the lead researchers, Dr. Bernhard Zipfel, when commenting on his findings, lamented that the American Podiatric Medical Association does not “actively encourage outdoor barefoot walking for healthy individuals. This flies in the face of the increasing scientific evidence, including our study, that most of the commercially available footwear is not good for the feet.”

Vivo BarefootOne of the newest designs discussed in the article is the Vivo Barefoot, which has a surprising link to the Alexander Technique.

Tim Brennan [is] a young industrial-design student at the Royal College of Art. Brennan was an avid tennis player who suffered from chronic knee and ankle injuries. His father taught the Alexander Technique, a discipline that studies the links between kinetics and behavior; basically, the connection between how we move and how we act. Brennan’s father encouraged Tim to try playing tennis barefoot. Tim was skeptical at first, but tried it, and found that his injuries disappeared. So he set out to design a shoe that was barely a shoe at all: no padding, no arch support, no heel. His prototype consisted of a thin fabric upper with a microthin latex-rubber sole. It wasn’t exactly a new idea. It was a modern update of the 600-year-old moccasin.

Brennan brought his shoe to Clark [inventor of the Wallabee shoe], and after some modifications, they came up with a very flexible leather shoe with a three-millimeter sole made of rubber and puncture-resistant DuraTex that they call the Vivo Barefoot.

Bending backwards for babies and ballet

I currently have three pregnant students, all at slightly different stages, so the following item captured my attention. I think this might also explain why women dancers – not to mention gymnasts – can bend backwards so much further and easier than men.

Nature has a new article detailing the recent discovery that women’s spines have evolved to be more flexible and supportive than those of men to increase comfort and mobility while bearing the weight of a developing child. The adaptations can be traced back as far as Australopithecus, more than two million years ago.

A female australopithecine, like today’s moms, used her spine to support baby’s weight.
John Gurche

Katherine Whitcome and Daniel Lieberman from Harvard University in Cambridge, together with their colleague Liza Shapiro of the University of Texas at Austin, measured the centre of mass of 19 pregnant women and found that they leaned back by as much as 28º beyond the normal curve of the spine, they report in Nature 1. The researchers found this lowers the torque around the hip created by the baby’s weight by roughly eight times.

Exaggerating the curve in the lower back can place more stress on the spine: vertebrae are more likely to slip against each other, leading to back pain or fractures. Whitcome and her colleagues found that a woman’s spine has several features that help to prevent that damage. In women, the curve in the lower back spans three vertebrae; in men, it encompasses just two. The added vertebra helps distribute the strain over a wider area.

In addition, specialized joints located behind the spinal cord, called zygapophyseal joints, are 14% larger relative to vertebrae size in women than in men, suggesting that the joints are well adapted to resist the higher force. The joints are also oriented at a slightly different angle in women, allowing them to better brace the vertebrae against slipping.