Barefoot running: Biomechanics

2010 April 6
by Daniel Lakeland

About a year ago I decided to start running more as exercise (this didn't last long since I lost my running partner when my wife got pregnant). I have been a cyclist for many years, but generally avoided running since High School. When I was in High School I injured both legs, one after another, because of a pair of early Nike Air running shoes. The high cushioned heel led to instability and I rolled my ankles, injuring the growth plate of my fibula (the small outside ankle bone).

When I decided to start running more, I needed a pair of shoes. Based on some vaguely remembered articles, I started looking up barefoot running and minimal shoes. This is a hot topic, and my wife recently sent me the following link on barefoot running:

Barefoot running: How humans ran comfortably and safely before the invention of shoes. You can also go see the Nature article this refers to, or the News and Views commentary in Nature.

The biomechanics is pretty much straightforward. If you use cushioned heel shoes you will naturally stiffen your leg and land on your heel, leading to a sudden high-impact collision. This is an inevitable consequence of your brain adapting to the shoe design. When you wear a minimal shoe, not the Nike Free which is called minimal but is actually a tank, but something really minimal like a so called running flat, or a moccasin, or a sandal, you will naturally learn to absorb the impact by landing towards the middle or ball of your foot. This produces a lower impact force than if you were heel-striking in a fancy shoe, even on concrete! In other words, unsurprisingly, humans evolved a mechanism to run without fancy shoes invented in the 1970's. Amazing! (sarcasm doesn't translate well to the internet).

Unfortunately, the graph associated with the article is not very good. The peak for the front foot striking barefoot runners is significantly lower than the peak for the heel striking shod runners. The fine print says that the peak is 0.58 +- 0.21 bodyweights for the barefoot, and 1.74 +- 0.45 bodyweights for the shod heel-strikers.

For someone with well developed foot calluses, like my habitually barefoot friend Paul, running barefoot is a great option actually. For those of us who have delicate foot skin and worry about abrasions, punctures, or lacerations, there are shoes like one of the Adidas AdiZero running flats (which is what I eventually settled on). When I run in that shoe I feel every small twig or rough bit of the pavement, and I naturally run in a more forward striking gait since there is a very limited heel. Some people like the Vibram Five-Fingers and the like (basically a moccasin).

Biomechanics is a fascinating subject that I would like to do more with in the future. I'm particularly interested in musculo-skeletal structure and bio-fluid-mechanics. Maybe I'll write something about the Rorqual Whale lunge-feeding article in American Scientist soon.

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