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Lead Stories: Saturday, November 22, 2008

“Concrete vs. Asphalt” - Which is the Better Running Surface?

Posted July 28th, 2006 at 5:30 AM by Jim Fortner

Section: Running & Training, Injury & Rehab, Training Tips, Health & Fitness, Injury & Rehab, Exercise

A note from the TFS: We are pleased to welcome Jim Fortner as a guest contributor to The Final Sprint. Jim is an extremely knowledgeable runner and talented writer. Make sure to also check out “Jim2’s Running Page”, his own personal running and advice site.

Below you will find his latest post concerning the debate over running surfaces - what’s better: concrete or asphalt?.

asphalt concrete running_edited-2.jpgConcrete is a much harder surface than asphalt or macadam. It’s the worst commonly encountered surface that you can run on and should be avoided like the plague. To compare the “hardness” of concrete and asphalt, hit each surface with a hammer and see how it feels to your hand and arm. You will find quite a difference. You will leave a dent in the asphalt, but not in the concrete.

When running, your feet strike the surface with a force of up to 6 times your body weight. And unless you land dead midfoot all that force is concentrated on a very small landing surface. For a typical heel striker, it’s maybe a square inch or two. Let’s assume that a person who weighs 120 pounds lands at 5 times body weight with a heel strike that covers two square inches. That’s equivalent to an initial strike force of 300 pounds/sq in (equivalent to 3600 pounds/sq ft) upon contact. If asphalt is really 10 times “softer” than concrete, as the study that Bill mentioned said, that would make a big difference in initial energy dissipation vs that which shoes, normal pronation and body structure have to absorb. (BTW, that’s also the problem with a non-overpronator using stability or motion control shoes. They unnecessarily restrict normal pronation, which is a natural shock absorption biomechanic, and result in an increase in the force that the body’s skeleton and joints have to dissipate.)

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