Running Shoes & Gear? That's a bit of a controversial topic these days, with people like Chris McDougall arguing that "presented over the summer at the American Society of Biomechanics meeting" that don't help and probably hurt you. What Is Foot Reflexology, Rodger Kram and his colleagues at the University of Colorado published a neat study that showed that the cushioning in running shoes actually saves energy when you run. Without cushioning, the theory goes, your leg muscles have to do some work to absorb the impact of landing, which costs energy.
That first study compared shod and barefoot running, using small weights to equalize the mass on the runners' feet. (For every 100 grams of shoe mass, you spend about 1% more energy running.) That left open the question of whether strapping these small weights to the runners' feet distorted the results. The new study, by Kryztopher Tung, Jason Franz and Kram, presented over the summer at the American Society of Biomechanics meeting, gets around that with a totally different approach: "invisible shoes." [EDIT: I had the phrase "invisible shoes" bouncing around in my head for some reason, but a more accurate description would be "massless shoes." -AH] Treatments for Plantar Fasciitis!
Seriously.
They used an old-style treadmill with a firm, bounce-free belt. They tested energy consumption in a group of 10 experienced barefoot runners, running both barefoot and in Nike Frees weighing 211 grams. As expected, the cost of running was about the same in both conditions -- the extra energy burned by the weight of the shoes was almost exactly balanced by the energy saved by the cushioning.
Then they covered the entire treadmill belt with 10 mm of EVA foam -- exactly the same material used for cushioning in the running shoes, and roughly the same thickness. When the runners ran on the cushioned treadmill, they burned 1.91% less energy than they did running barefoot on the hard treadmill. Here's the data:
Now, burning less energy doesn't have anything to do with injury risk, of course. It's still entirely possible that shoe cushioning leads people to adopt a running form that makes them more susceptible to injury. That's a question for a different day and a different study (or rather, large set of studies).
One additional thought. If cushioning saves energy but the mass of shoes costs energy, wouldn't the fastest way to run be barefoot on a perfectly cushioned track? I asked Dr. Kram if such a thing existed, and he mentioned How to Treat Cracked Heels, built in 1979 and specially tuned to have optimal compliance, designed by Dr. Kram's mentor Tom McMahon and his student Peter Greene. I've heard tales of that track, but don't know many of the details. Has anyone tried running barefoot there?
