Biomechanics of Sport Shoes: The disturbing truth about running shoes, inserts and foot orthotics

By Dr. Michael Nirenberg, America’s Podiatrist February 24, 2011

A middle-aged woman arrived at my office last week complaining of heel pain and carrying a bag of custom-made foot orthotics (orthotics are custom made arch supports that are fabricated from a mold of the patient’s feet). Each orthotic this woman had with her was expertly fabricated by a different podiatrist and yet none of them had come close to alleviating her heel pain. At first I thought maybe these podiatrists didn’t know what they were doing. But, when I learned their names, I knew this woman had seen competent, skilled and reputable physicians.

I asked myself “how could this be?” More interestingly, no two sets of orthotics were even remotely alike. Further, given that nearly all podiatrists learn similar principles of biomechanics, shouldn’t orthotics for a given patient be the same regardless which podiatrist makes them?

After reading Biomechanics of Sport Shoes, Dr. Benno Nigg’s newest book, I have the answer. It is sobering, disturbing and I don’t want to believe it.

Unfortunately, Nigg is one of the top biomechanics researchers in the field of sport shoes, foot inserts and foot orthotics in the world. In fact, I imagine that Nigg spends more time thinking about biomechanics than a 17 year old boy spends thinking about sex.

Foot Orthotics Debunked!

Nigg reveals that foot orthotics, which are devices designed to align misaligned feet, are actually not aligning the skeleton at all. In fact, Nigg’s book reveals many disturbing facts about orthotics, shoes and inserts: including that there is weak evidence orthotics lessen injury. Furthermore, changes in skeletal alignment due to inserts or shoes are inconsistent and minor.

Most importantly, Nigg goes on to warn that one of the dangers of the consistent use of orthotics is that they reduce functional demand on muscles and may be associated with the deterioration of the muscles’ strength and function. So even though a foot orthotic often helps in the short term, over the long term Nigg warns their use may cause problems.

Repetitive Impact Not As Bad As We Thought!

Beyond orthotics, Nigg dispels the notion that running injuries are due directly to impact forces and suggest that the new paradigm should be “muscle tuning” and the minimizing of vibration of the runner’s soft tissue. Nigg asserts that injuries are generally a result of intensity, duration, and recovery time.

Excessive Pronation May Not Be A Problem

Nigg then reviews foot, ankle and leg biomechanics research and shows that there is no evidence that excessive pronation when walking or running is a cause of injury. This finding is dramatic because many podiatrists believe excessive pronation is the root of many foot problems.

Barefoot Running May Not Be Any Better

Despite Nigg debunking shoes, inserts and orthotics, you may be tempted to believe he must be a proponent of barefoot running. Not so. Nigg does not believe there is any evidence currently that barefoot runners sustain fewer injuries than shod runners.

However, rather than closing the proverbial shoe box lid on barefoot running, he does say “barefoot training” is important and admits that barefoot running has a “small” performance advantage, but it may only be beneficial for a small group of runners.

He speculates that the functional adaptations of footwear based on the bare foot are positive and may persist, but the fashion adaptations based on the bare foot will disappear in relatively short time.

Are You Ready To Be Unplugged?

Dr Benno Nigg, the co-director and founder of the University of Calgary’s Human Performance Lab in the Faculty of Kinesiology, has written the book: Biomechanics of Sport Shoes which suggests that the shoes you wear aren’t as important as people once thought. Riley Brandt © University of Calgary 2011

One has to wonder about the long term effects of the Biomechanics of Sport Shoes. Clearly, it should be required reading for every podiatrist.

However, it may be difficult for some podiatric physicians, particularly those who have spent their life doing sophisticated biomechanical exams on their patients and meticulously fabricating foot orthotics, to open their minds to the content of this book.

Beyond health practitioners, patients themselves still generally believe arch supports, running shoes and foot orthotics are well-understood and the answer to their running injury woes. Until people begin thinking for themselves and asking questions both to themselves, to their doctors, and to the running shoe and arch support companies, the system will feed them what it always has.

I am reminded of a great quote from the film The Matrix

The Matrix is a system, Neo. That system is our enemy. But when you’re inside, you look around, what do you see? Businessmen, teachers, lawyers, carpenters. The very minds of the people we are trying to save. But until we do, these people are still a part of that system and that makes them our enemy. You have to understand, most of these people are not ready to be unplugged. And many of them are so inured, so hopelessly dependent on the system, that they will fight to protect it.”

On a personal note, I vigorously applaud Nigg for not only puzzling-out the mysteries of sports shoes, orthotics and running, but for having the courage to put his theories into the public domain.

If you are ready to open your mind to the latest information and theories on running, sport shoes and foot orthotics, I urge you to read Biomechanics of Sport Shoes.

Source America’s Podiatrist

References

Biomechanics of Sport Shoes, Benno M. Nigg. Topline Printing Inc. 2010 ISBN 978-0986742101

Orthotics work in mysterious ways, Collier R. CMAJ. 2011 Mar 8;183(4):416-7. doi: 10.1503/cmaj.109-3802. Epub 2011 Feb 14. Full text