The Harvard Indoor Track Revisited
I live in Charlottesville, Virginia, home of the University of Virginia (UVa), where I recently retired as professor and chair of the department of physical medicine and rehabilitation to launch OESH Shoes. Though I love UVa, I must admit a lot of good things come from dear ol’ Harvard. The inspiration for completely re-inventing the athletic shoe came from my years at Harvard Medical School (where I also received my M.D.), studying gait and footwear. While a lot of the concept for OESH came from my own biomechanical studies on gait and footwear, some of it also came from the work of a fellow Harvard researcher, Thomas McMahon, a biomechanical scientist who I overlapped with slightly. I haven’t heard his work much mentioned lately but think it deserves re-visiting. Any legitimate discussion attempting to determine whether or not an athletic shoe midsole could ever reduce injury north of the foot has to consider his work.
Dr. McMahon studied the effects of imposing a compliant surface between the foot and an otherwise hard ground surface. By compliant, he meant a surface that compressed and released in tune with the rise and fall of the body’s center of mass during running (and jumping). To do this, he first built a workable compliant ground interface that would consistently compress and release in a laboratory environment. After considering a number of different compliant-like surfaces, the one he studied extensively was a simple sheet of plywood draped across 2X wood supports on either side. He had subjects run up and down the middle of the plywood and measured the deflection of the plywood in relationship to the rise and fall of the subjects’ center of mass (measured with markers placed over the subjects’ trunks). He experimented with changing the compliance of the plywood by changing the distance between the wood supports. And he found a perfect window of compliance (the Goldilocks structure – not too compliant and not too stiff) that increased stiffness in the lower extremity while simultaneously reducing foot contact time.
All that was just the groundwork (so to speak) for his next experiment–which may be the best controlled scientific experiment regarding the effect of human ground interface on injury rate ever done. What he did was incorporate his plywood structure into the Harvard Indoor Track. This was completed, along with help from Dr. Peter Greene, in 1977. Dr. McMahon’s plywood structure was placed on top of the existing hard surfaced indoor track. Essentially, the track comprised plywood draped across wood supports that ran between the lanes (covered by a thin polyurethane layer). This matched the surface from his laboratory work meant to reduce stresses and strains throughout the body. McMahon hypothesized that the compliant surface should not only reduce injury, but also improve running efficiency.
I’ll discuss what this Goldilocks surface revealed in my next post. Until then, I’m off to have some porridge before today’s run.