What *is* G-Max testing and why do I need it?

Pick up any newspaper, or more likely, click on any news link and there will be something mentioned about sports-related injuries.  It’s a very real and valid concern for parents, coaches and athletic directors alike.  Many parents don’t want their children playing contact sports due to the possibility of injuries. 

G-Max = The maximum gravity force (“Gs”) a playing surface absorbs the shock of an object.

Thanks to years of scientific studies, measures are being taken to prohibit or lessen the likelihood of injuries where possible.  One of those measures is the testing of shock attenuation on playing surfaces, or G-Max testing.  A G-max test is a test performed on athletic playing fields that measures the force with which a body strikes a playing surface and the feasible rate of injury during a fall.  Special equipment is used on both synthetic and natural grass surfaces to test in units of gravity, which is the pressure and shock the body experiences during surface impacts.  When used properly, the G-Max testing unit produces a range of numbers for the operator to see just how hard or soft the playing surface is.  The higher the G-Max results, the lower the shock absorbency is.  A good analogy regarding G-Max testing from NFL.com is, Think of this as dropping [a] missile onto concrete. If the missile was dropped onto a pillow, it would take a longer time for the missile to stop and the softer surface would produce a lower G-max value.”  While it certainly won’t feel like you’re falling on a pillow, it won’t necessarily feel like you’re falling on cement, eitherThe purpose of these tests, aside from the obvious – you don’t want your children or athletes injured – is to ensure that you’re getting the maximum benefit and use out of your playing surfaces.  According to Penn State’s Center for Sports Surface Research, 10% of concussions are caused by the impact of the head with the playing surface. 

For more wordy, nerdy information and examples, click here

Turf, Track & Court LLC has 2 devices used to measure impact, depending on the playing surface.  The Clegg Impact Soil Tester is generally used to test natural grass surfaces to see how hard the hit will be when an athlete comes in contact with the ground.  During the test, a 5 pound cylindrical hammer is attached to a control unit, then pulled up to a precise height and released by the operator.  The impact of the hammer produces a pulse which is converted on the control unit to gravities.  Definite wear areas are tested first, as are any potential spots of concern. 

The other device used is the Triax 2010.  This device is used for synthetic turf and artificial surfaces.  The Triax is a tripod system that does the same task as the Clegg, it will also measure the impact attenuation.  With the Triax, however, the unit is on a free standing tripod, and the operator pulls a pin to drop a 20 pound hammer from a predetermined height.  By utilizing the tripod and pin, some human error can be eliminated versus manually dropping the hammer.  This test is repeated three times at each of the 10 locations of the playing surface to adhere to ASTM guidelines.  The end result for both devices is how abruptly the hammer strikes the ground.  Both units provide immediate results.  Regardless of whether you have turf or natural grass, it’s highly recommended to have your playing surfaces tested annually for safety purposes and for maintaining a baseline. 

Various elements can affect the results of a G-Max test.  The amount of infill material used to support the synthetic turf can alter the results, as well as the composition of the infill.   As with anything that’s used over time, the infill moves around which is why regular maintenance is also important for your synthetic turf.  For natural surfaces, the type of soil and the moisture content will affect the G-Max test to varying degrees. 

There are many products that claim to help ease the effects of concussions and injuries, or stop them altogether, but it’s not as easy as that.  There’s no fool-proof way to prevent injuries, although maintaining your playing surfaces and teaching your athletes to play safely and play smart while still staying competitive will help.  

Danielle Hammond is our designated operator for each of the units.  To schedule a test or find out more, please give us a call at 717-312-3012 or send an email to info@turftrackandcourt.com.  We’re happy to answer any questions you may have.