THE HUMAN FOOT & SHOES

Many foot ailments – plantar fasciitis, collapsed arches, bunions, hammer toes, high ankle strains, and all sorts of other maladies – are exacerbated by the very technology that allowed humans to inhabit the globe: shoes.

Footwear helped humans spread into northern latitudes and eventually the Americas. Today, shoes allow one to play blacktop basketball and hike in the woods after a nor’easter. High ankle boots protect against snakebites in the grasslands of Australia and sub-Saharan Africa. Footwear protects against broken glass at the beach or along city sidewalks. Or it simply allows one to buy something at the store since “no shirt, no shoes, no service.” Without shoes, humans wouldn’t have summited Mt. Everest or walked on the moon. There were and remain an important technological innovation. But as is true for many of our cleaver inventions, there are costs that accompany these benefits.

The bottom of your foot contains ten muscles, arranged in four layers. Some of these muscles maintain the foot’s arch while others are critical for propelling us into our next steps. But most shoes, even the wholesome-sounding “arch-supporting” ones can weaken these muscles. The result is a foot more prone to injury.

The Tarahumara are an indigenous people in Mexico known for their exceptional distance-running abilities. Their sandals are usually made from a piece of car tire rubber and held to the foot with string. Human evolutionists studying the Tarahumara to see how they walk and run also used ultrasound to measure the size of their foot muscles. The Tarahumara have higher arches, stiffer feet, and larger foot muscles than the typical American.
Maybe the Tarahumara are just genetically predisposed to have strong foot muscles? The size of two-foot muscles was measured in 33 runners. Half of the runners trained in their normal, cushioned running shoes. The other half transitioned slowly to a minimalist shoe – more like the Tarahumara wear. After only 12 weeks, the minimalist shoe-wearers had increased the size of the two-foot muscles by 20% and their arch was stiffer by a whopping 60%. Our feet change because of the shoes we wear, or don’t wear.

Not only that, but without strong foot muscles, the plantar aponeurosis – that band of tissue that spans the bottom of the foot – can become over-strained, resulting in the stabbing pain of plantar fasciitis. We have lulled ourselves into thinking that our feet need cushioning to survive.

To boot, shoes no longer just protect the feet. They are gendered symbols of social status, wealth, and power. Our feet pay the price. High-heeled shoes shorten the calf muscles and tighten the Achilles tendon, changing how we walk. Repeatedly squeezing the end of our feet into the narrow, pointed shoe box of a shoe increases the chances of developing bunions and hammertoes. These damaging effects disproportionately impact women’s feet and sometimes require surgical intervention.