Talking Biomechanics with Benno Nigg, PhD

by Ben Pearl, DPM

The following is excerpted from an interview American Running Association Clinic advisor Ben Pearl, DPM, conducted with Beno Nigg, PhD. Originally conducted with a podiatrist audience in mind, regular readers of Running & FitNews® will easily absorb the finer points of the talk, as running and fitness enthusiasts used to the world of shoe science, podiatry, and evidence-based conclusion drawing.
Much is written about biomechanics. The breadth information is overwhelming and only some of it is relevant. Podiatry can claim partial success in staying current with the literature and leading new research, yet veteran biomechanics researcher Benno Nigg, PhD, encourages us to remain both open-minded and cautious in podiatric practice regarding what is scientific fact and what amounts to podiatric folklore.
Dr. Nigg spent much time on the investigative side of the running shoe industry as a hired consultant for shoe companies before turning his focus to pure research. He is very careful not to draw conclusions that are inferences when he reviews studies. For example, when asked about heel strike vs. forefoot strike and research on injury patterns, his first question is whether the runners are shod or barefoot—conclusions drawn from one group won't translate to the other. If you think the science of biomechanics is static, Dr. Nigg asks you to think again in his recent book, Biomechanics of Running Shoes: The Disturbing Truth About Running Shoes, Inserts and Foot Orthotics.
—Ben Pearl, DPM 
Why should runners read your new book?
Podiatrists and runners that are interested in the actual functioning of the lower extremity and in the reasons for specific intervention may get some help when reading this book.
What do you think the role of podiatry should be with runners given your [conservative] view of orthotics?
Orthotics can play a major role in terms of initial recovery from injury. In my view the podiatrist's stratetgy should be to combine initial orthotic use with recommending strengthening exercises for the small muscles crossing the ankle joint. I also see a role for orthotics in clear structural issues such as an anatomic leg length discrepancy.
What major studies have caused you to change your views about shoes?
 There are different aspects where we changed our view substantially. Typically, we had results from a series of studies that did not support our initial speculations. For instance:
Impact forces: Initially we thought that impact forces are dangerous and that we have to change shoes and orthotics to reduce external impact forces. A series of studies showed that (a) epidemiologically, impact forces are not a good predictor of running injuries, and (b) external impact force peaks are not sensitive to the hardness of the shoe.
Excessive pronation: Again, we thought initially that “excessive pronation” would be dangerous and that we should change the shoes to reduce pronation. A series of studies showed that pronation is not a good predictor of injuries.
How do you reconcile anecdotal observation of increased injuries like tendonitis and stress fracture from wearing “five-finger” shoes, with having no hard evidence for it. How should the average clinician assimilate this?
I don’t know how the average clinician should react, except that he/she should functionally analyze every single case and provide functional interventions. Scientific studies should be initiated to assess the actual epidemiology of all these new “footwear solutions” and assess the actual effects of these interventions with respect to epidemiology and biomechanics.
What do you see in the future for running shoes?
Future running shoes will have more functional characteristics, they will be lighter and less bulky, and some shoes will have sensors to help improve the “ride.”
What role do you see for core stability and fatigue in causing injuries and what research do you think substantiates this?
There are two major strength centers in the body that are currently associated with injury and reduction of injury: the core strength and the strength of the muscles around the ankle-joint complex. There is initial evidence that strengthening both of these muscle centers has a positive effect on reducing injuries. However, the results are initial and need more work. Intuitively, the two concepts seem sound.     

What should the podiatry schools be emphasizing in biomechanics classes?
I think the major emphasis should be on functional biomechanics and functional solutions. Often, podiatrists want to solve every problem with an orthotic. If the problem is in the Achilles tendon, the emphasis for finding a solution should be on reviewing the mechanics of the Achilles tendon.

Ben Pearl, DPM, FACFAS, runs the Arlington Foot & Ankle podiatric clinic in Arlington, VA. He was recently selected as one of Washingtonian Magazine's top sports doctors.

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