Paul Harvey did a “the rest of the story” segment on one of my first research studies on shoes. He was a nice guy and I was in awe of his digging in beyond the typical headline news. In that same vein, I now give the rest of the story on another of my studies published about a year ago–this one on traditional running shoes.
The study received a lot of attention by the press and is often cited in barefoot-versus-shoe running forums and discussions. Reporters were all over one main point…that traditional (non-OESH) athletic shoes increase the peak knee and hip joint torques linked to the development of osteoarthritis. But what has not been well covered is when these injury-relevant torques occur in the running cycle.
Frequently, the study is described by an eye-catcher such as: “Recent research shows that running shoes increase impact forces at the knee and hip.” Perhaps because ‘impact’ sounds so awful it’s been blamed for just about every walking and running related injury, including the most significant, knee osteoarthritis (which we all get to some degree if we’re lucky to live long enough). But our research broke through a glass ceiling of assumptions and showed that these increased forces or torques were not occurring at impact.
In fact, the joint torques and forces at impact are very small.
Rather, the increases in the injury-related torques occur when the foot is fully planted.
Below are some of the graphs that were published in the article. You can see that when the body’s impact force is at its maximum (shown with arrows), the knee joint torques are not only very small, they can be negative (as in the first graph)–meaning the force at impact is in the opposite direction of where osteoarthritis even occurs!