One of our friends, journalist Max Lockwood of Running Insight magazine, cut to the chase by asking me a few simple questions this week: What is torque and How bad is it for the runner?
To properly answer Max, I referenced the landmark study we published in 2009, when I was director of the University of Virginia (UVa) Gait Laboratory. We showed that traditional running shoes increase joint torques compared to barefoot. The study received a lot of press and you can find coverage of it online…a site that has the entire pdf available is here.
I included in the introduction and the discussion the meaning of torque, which is, in a nutshell, the body weight force applied a distance from a joint, as well as its potential medical significance. Generally, greater joint torque implies greater forces and pressures through the joint. Peak joint torque is a function of peak body weight force which occurs not at the moment of impact but when the foot is fully planted.
We can only guess from this study that the raised heel was a factor in raising joint torques because of my previous studies first at Harvard and then at UVa showing that high heeled shoes similarly increase joint torques. The other factors that are likely to play a role are the general foam cushioning and inherent arch support in traditional shoes.
The fallacy in thinking has been that cushioning in shoes somehow reduces pressure on joints. But in fact, foam, gel, “air” cushion and the like simply absorb energy without giving it back, which makes the joints have to work even harder. This in turn, places greater demands and thus greater torques, forces, and pressures on the joints. Any sole/surface that doesn’t both give and fully respond back is only going to increase joint torques. This is in contrast to OESH, the Harvard Indoor Track, and a perfectly compliant natural ground surface, which all DO both give and fully respond back. Regarding torque, I always explain the physics by the example of moving a frozen bolt…you can’t do it with a tiny wrench, but increasing the torque via a long handled wrench will move anything…now imagine what that excessive torque might feel like on your joints.
As OESH keeps growing, I suspect it’s because you can feel the difference throughout your feet, legs, hips, back, and especially in those joints.
Or…you just love the way OESH looks. Speaking of which, check out our new athletic sandals, which you can even, if you’d like, RUN in!
And Max…Thanks for asking the right question.