When looking at the traditional running shoe, or almost any shoe that is customary in our society, one observation becomes common- the heel. What is the reason that shoes have heels? That is a very good question. The origin of the heel dates back to King Louis XIV of France in the 1660s which was used amongst regal to demonstrate power. It obviously has been passed on through the years in both fashion and normal anatomy to shoes, but is it needed?

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King Louis XIV.

 

The running shoe has many origins, but many agree that athletic shoes began as a canvas top and rubber soled shoe that was referred to as  a sneakers when U.S. Rubber used the brand name Keds to sell the first sneakers in 1917.  The next major milestone comes in the 70’s when Bill Bowerman and Phil Knight created the Nike running shoe.  These early shoes had little if any cushion and for the most part had a negligible heel.  Over the next 40 years we have seen the height as well as the cushion gradually increase which inadvertently hassled many runners to adopt a “heel to toe” gait or “heel strike” when running.  This height became referred to as “drop”- the distance in height between the heel of the shoe and the forefoot.   Today traditional running shoes have a drop of 12 mm with the heel being 24 mm and the forefoot being 12 mm.  This design encourages an unnatural gait resulting in the  heel hitting the ground first, followed by a rapid “slapping” of the forefoot.


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The cushioning that running shoe manufactures incorporate into the heel leads the runner to “feel” as if the shock is being absorbed by the shoe with each step. While this is true, only a small amount is actually absorbed by the shoe, and the rest of the force (2-3 x the body weight) is actually being transferred through the lower extremity. This is confirmed by Newtons 3rd law and was demonstrated experimentally by Leiberman et al.(1)  They were also able to demonstrate that by running barefoot, we tend to land more on our forefoot or midfoot  to innately reduce the force that occurs to the leg. Try running barefoot and you will see that it is rather painful to land on your heel and that landing on the forefoot becomes much more comfortable.   In order to do this properly, the forefoot needs to strike the ground first in the region of the 4th and 5th metatarsal with the heel slightly off the ground. The same force that was rapidly transmitted the heel, is now transferred to rotationally force as the heel lowers to the ground thereby astronomically reducing the force that occurs to the lower leg.

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Foot striking the ground with no heel. Forefoot lands first with rearfoot rotating to bring heel to ground, converting to rotational force.

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Foot striking ground with heel. The heel blocks the ability to allow rotational force conversion increasing the impact.

It becomes very simple to see that when wearing a traditional running shoe, even if one lands on the forefoot, the high cushioned heel interferes with the ability to lower the rear foot to the ground. This prevents the rotational mechanism and therefore actually increases force to the forefoot.

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Barefoot at moment of impact demonstrating the approximate degree of angle before heel is lowered to ground.

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Foot in traditional running shoe depicting heel height.

 

Even more fascinating, is what happens to our posture when we simply stand in a shoe with a heel.  The clog by Dansko, which has become very popular among medically professionals, has an elevated heel which drastically changes normal anatomical posture increasing force to the lumbar area of the back (not to mention the 4 pound combined weight if the shoes!).

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Increase in posture when wearing a heel.

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Change in ankle joint to accommodate the heel height. Foot now resting in non anatomical position.

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Body’s position to become neutral.

 

To summarize, the height of the heel that is present in the traditional running shoe, not only tricks the body into feeling that the force is being “cushioned” by shoe, but also interferes with the foots ability to naturally dissipate the force.

 

 

References:

 

1. Lieberman DE, Venkadesan M, Werbel WA, Daoud AI, D’Andrea S, Davis IS, Mang’eni RO, Pitsiladis Y. Foot strike patterns and collision forces in habitually barefoot versus shod runners. Nature. 2010 Jan 28;463(7280):531-5.

 

2.  http://en.wikipedia.org/wiki/Shoe

 

3.  http://www.footwearhistory.com/introconstruction.shtml

 

4.  http://www.articleclick.com/Article/The-Evolution-of-Athletic-Shoes/936749

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