Athletic fields and concussions: The key to safety is maintenance

August 1, 2014 David Nardone

With concussions a growing concern in sports, proper field maintenance is more important than ever


As we all know, concussions have become a major – if not THE major – issue in competitive contact sports, from the pros down to the pee-wees. While a number of factors come into play when it comes to concussions, one that we have some control over as field designers is the field surface itself. By properly maintaining and monitoring a field’s turf, we can at least minimize any safety concerns the playing surface could pose for player safety.

First, test. Turf safety is measured by what’s called a G-max test, which measures the shock attenuation of a surface by dropping the equipment’s “missile” onto the turf and measuring the resistance and absorption rate. The resulting G-max value represents the ratio of deceleration upon impact to acceleration due to gravity. In other words, it measures how well the turf absorbs and slows the impact.


Backhoe doing maintenance on the field turf


Right now the American Society for Testing and Materials (ATSM) and Synthetic Turf Council recommend keeping the G-max level below 200 (although there is talk of lowering it to 165). The NFL is testing requiring teams to maintain their fields below 165 as well. These lower numbers stem from growing research on concussions showing that any safety enhancements can help. So the lower the turf’s G-max value, the greater safety buffer the surface can help provide.

Typical natural grass turf systems inherently have a lower G-max value – usually in the 80-110 range. So, synthetic turf manufacturers are trying to create systems that get closer to those naturally lower levels, which typically involves designing a field with a padded turf. But the variety of soil profiles in a field area, particularly in a city, make the safety level of natural grass fields harder to predict. While the NFL now tests its fields before every game – synthetic or natural – lower levels of competition don’t have the resources to maintain that same kind of rigorous program to ensure the turf is at safe levels.

Maintenance, maintenance, maintenance. The best course for keeping G-max levels under the recommended standard depends on the level of play and the field system in place. Padded systems on fields only used by one sport per season, for instance, are easiest to keep in the lower G-max value range. But for many sports programs, that kind of exclusivity isn’t reality. The most effective way to keep a field in its best and safest playing condition is aggressive, field-specific maintenance.

Depending on the field and the level of play, a maintenance schedule should include a series of checks and improvements throughout the year. For a synthetic field, that could include regularly checking infill depths to make sure the infill is uniform across the field. A field’s shock resistance may lessen over the course of a season, too, so testing it more than once ensures the levels stay in that lower range.

Maintenance is just as important for natural turf, too. Annual aeration is critical to decompacting the soil for the turf plants and helps the attenuation level of the natural grass level.  Maintaining sufficient grass cover is also critical in providing a safe field. 

After conducting these sorts of regular field investigations, you get to know how the field reacts to your level of play and how attenuation levels change, so you can tweak the maintenance frequency to help the G-max levels stay consistently within the acceptable safety range over the course of a season or two. If that isn’t working, that’s a clue that another factor may be the issue.

The issue of safety, and concussions in particular, will only continue to get more scrutiny at all levels of play. While the field system in place and regular testing can help, maintenance is truly the best means for keeping your turf in the safe zone and doing your best to ensure the field is one less safety issue for players, coaches, and parents, to worry about.


*This is an abridged version “Turf and Concussions: Maintenance for Safety’s Sake,” which ran in the June 2014 issue of Parks & Recreation magazine.

About the Author

David Nardone

David Nardone is a landscape architect in our Boston office. He leads our sport group in the design of athletic fields, stadiums, courts, athletic surfacing, and athletic master plans.

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