Injury and Traction Measurement on Playing Surfaces

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Athletes interact with a playing surface through falling on it or through complex athlete to shoe to surface interactions.  The shoe to surface interaction is referred to as traction. We measure traction for two reasons: performance and injury risk. Imagine a wide receiver pushing off at the beginning of the play. What happens at the shoe sole - surface interface is 'linear traction.' As linear traction increases, agility and speed increases. This can be measured using human performance tests where athletes in designated footwear run time trials or perform other maneuvers where the forces involved are measured. Due to the myriad of shoe and surface types, and player weight and strength variables, it can become expensive and time consuming to measure traction characteristics using human subject tests.


In order to more efficiently measure the shoe to surface interaction, material tests have been developed where a machine is used to imitate human movement and collect traction data. While these machines provide valuable insight concerning the shoe - surface interface, the lay person shouldn't read too much into injury risk predictions generated by material tests. Remember, the complex movements and subtle adjustments made by an athlete are not included when measuring traction using material tests.


Most ACL injuries are due to rotational torque in the joint. Injury risk is often evaluated by measuring the amount of resistance to shoe rotation. Researchers have postulated that as resistance to rotation increases, the potential for lower extremity injuries increases because a player's cleats will not "release" from the surface. Certainly a shoe - surface - player weight combination that produces high rotational resistance is not preferred, but researchers are reporting that non-contact ACL injuries are the result of a complex set of variables including speed to peak rotational resistance, surface hardness, and knee flexion at the time of quad muscle firing to name a few.


As you can imagine, measuring traction is not a simple task.  At Penn State's Center for Sports Surface Research, we have developed a traction testing device named 'PennFoot'.  Pennfoot's artificial leg and foot assembly allows us to measure both linear and rotational traction with any shoe on any surface.  Additionally, we can simulate various player weights, giving us the opportunity to compare traction measurements for athletes from the Pop Warner league to the NFL.  Beginning in 2001, we have been measuring traction on multiple synthetic turf products and publishing the results on our website: Here you will find traction information from research plots that have been exposed to simulated heavy use for the past nine years.


There is lots more research to be done before a definitive traction safety level can be established. In the meantime we will continue to produce and disseminate research results that benefit athletes, trainers, and coaches at all levels. 

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About this Entry

This page contains a single entry by ANDREW SCOTT MC NITT published on July 26, 2010 5:11 PM.

Say Hello to Students on Official Internships This Summer was the previous entry in this blog.

State of Connecticut Releases Report on Synthetic Turf is the next entry in this blog.

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