Advancements in Running Shoes

As a runner and an orthopedic surgeon, I have two reasons to keep abreast of the advances in running shoe design. The design of running shoes is experiencing a revolution. What started as a fringe movement of barefooted runners morphed into a fad of minimalist shoes and is now becoming a more mainstream trend towards light weight shoes with low heel heights.

All of this began with Christopher MacDougall’s book Born to Run in which he tells of the Tarahumara Indians who can run unlimited miles while only wearing what can best be described as a thin-soled sandal. The author observed that these Indians had a mid-foot strike which is vastly different than the heel-first strike, typical of most shoe-wearing runners.

The belief is that a natural running stride begins by landing on your mid-foot. This allows the foot to absorb the impact, store that energy, and ultimately release it at toe-off. It is hypothesized that the foot has evolved for this particular purpose. However, the modern shoe developed big, cushy heels that allowed for a heel strike. This heel-first approach stops forward motion and theoretically exposes the hip, knee, and ankle to greater forces and unnecessary stress.

From a biomechanical and evolutionary point of view, this made sense to me. Furthermore, there is literature to support the above theories. Studies have shown that runners wearing traditional shoes hit heel first and with greater force than barefoot runners, that shoes with a higher heel place greater stress on the knees, and that runners with a mid-foot or fore-foot strike experience less stress on certain joints. However, I have to say that no one has been able to show a direct cause-and-effect relationship between shoe wear and injuries.

So, despite being a relatively heavy, flat-footed runner who had never worn anything but bulky stability shoes, I experimented with minimalist shoes. I started with light weight trainers with a low heel height. And while I haven’t run barefoot since that one night in college, I do have a pair of Vibram FiveFingers. I can say one thing for sure; I will never wear my old stability shoes again. Not only are my lighter, lower shoes a blast to wear, they even look fast.

In my mind, there is something to these minimalist shoes, but you have to be careful. Long before I started changing my footwear, I started changing my stride, making a conscious effort to avoid a heel strike. A fore-foot strike produces approximately 42% more force in your Achilles tendon than a heel-strike, not to mention the additional stress on the plantar fascia. Predictably, my calves and Achilles tendon required some time to adapt (read pain and tendinitis). With any such drastic change, do it slowly and give it time. Finally, we are all a little different. For many biomechanical reasons, I will never be able to log more than a couple miles every once in awhile in my Vibrams while others may actually be able to run barefoot.

Either way, running shoes will never be the same, and our knees and hips have much to celebrate as a result.

-Robert J Purchase, MD

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