Resonance Frequency and why certain shoes just don't work . . .

Below is an excerpt from an article in Runner's World in November, 2010 entitled, "Less is More," analyzing a debate over what we should wear on our feet and Dr. Benno Nigg has done a lot of research with resonance frequency which in basically a phenomenon in which an object (in this case, our bodies and feet for runners) will vibrate violently (or too much) when exposed to a harmonic force (in this case, running shoes) of a frequency close to our natural frequency. The result is jarring and vibration which puts too load on the muscles, tendons and bones which can cause many problems including many of the running injuries we often talk about.

Here's the excerpt:

What the shoe companies are realizing (along with many runners) is that minimal isn't a static concept; what's bare bones to one person might seem like way too much shoe to another. How do you know what's right for you? The answer may one day come from the University of Calgary's Human Performance Lab, run by Benno Nigg, who has created many of the innovations that now frame the debate about minimalist shoes.

The Performance Lab is something of a birthing room for new and unconventional product concepts. In the early 1980s, Nigg was working as a consultant for Nike on its line of tennis shoes. While there, he offered input on the need to add more structure to Air models because the much-lauded Air units created even more instability than traditional foam. "I pushed the cushioning trend as much as anyone," the broad-shouldered Nigg says in his Swiss accent. "And I take the blame for pronation devices as well."

Much of his current research, though, is focused on the "soft-tissue vibrations" in the body. Nigg argues that understanding vibrations—such as the ones that shoot through our legs when our feet whack the blacktop—is the key to performance and may even lead to injury prevention. Every runner has a unique frequency generated by their muscles, called a resonance frequency. It depends on the unique type and size of muscles in your legs. When the vibrations from running come close to a person's unique resonance frequency, you feel discomfort. To check the kind of vibrations in runners, Nigg tapes electrodes to their legs while they are running. These painless sensors measure tiny electrical currents the muscle cells make when activated. Using higher math formulas called wavelet filters, he gets a useful picture of which muscles are firing and when—and what type of shoe would be ideal for an individual.

Since 2000, Nigg has placed electrodes on more than 1,000 runners, most recruited from the University of Calgary's sports teams and running clubs in the area. Some were rail-thin distance runners, others had the muscular carriage of sprinters or soccer stars. The upshot? Nigg has found that some runners' bodies are in tune with firmer shoes because they provide a high-frequency signal to the body, and other runners are in tune with softer shoes, which provide a low-frequency signal. If a shoe hits your natural resonance frequency, you feel uncomfortable after a few miles—and if you persist in wearing it, your muscles become overworked trying to counteract the nettlesome signals.
After explaining his research, Nigg sits down to draw his vision of the optimal shoe for the runner tuned to a minimal shoe. You might expect it to be something shockingly out of the blue—flying buttresses made of carbon-polymer or crash pads injected with flubberlike gel. But once he's through penciling in lines and arrows, his sketch looks, well, like a track spike. The future is a track spike?

"There's no cushioning on the forefoot. For function, it's unneeded," he says. "For comfort—eh, you put a little inside the shoe to distribute forces." With this prototype, Nigg is projecting out to a time when most shoes are ultralight. They do away with foam and instead use some kind of structural element to both cushion and stabilize. Ideally, they keep you running—and away from injuries.

Let me know what you think?

Harry