Artificial Turf Gmax Testing and Field Safety

Is your artificial turf field safe for events? That question should be asked and answered regularly to ensure optimal field performance, warranty and safety standards are kept. So how do you do it? Artificial turf Gmax testing is one answer.

When players fall on the field, the impact is absorbed in part by the player and field. The harder a turf field is on the surface, the less impact is absorbed by the field. Since the impact has to be absorbed by something, it is transferred to the player. This increases the likelihood of injuries, like concussions and broken bones.

And while a single concussion usually has mild long term effects, multiple concussions can cause permanent damage. Plus, data indicates players who have one concussion are more likely to have another, increasing the potential for further serious damage. For this reasons alone, testing the surface of any field surface for attenuation, particularly those used for impact sport, should be priority. This is where Gmax tests come into play.

What is a Gmax Test?

Simply put, a Gmax test measures two things, absorption and impact. A twenty pound missile (weight) is dropped through a cylindrical tube on several different locations of the turf field. Each location receives three drops. Once dropped, electronic measurements record how much of the impact is absorbed by the field and how much is returned to the athlete. Artificial turf Gmax testing highlights field trouble spots for owners. Compacted infill and hard spots are easier to treat if caught early.

How Artificial Turf Gmax Testing Works

The specifics of a Gmax test shed light on the importance of data as it relates to field safety. To expand on the overview above, a Gmax test is precise, measurable and consistent. The machine housing the twenty pound weight is hooked to an accelerometer to measure how fast the missile comes to a stop on impact. The 20 pound weight, or missile as it is known,  measures G forces experienced upon impact and several other calculations.

The results are measured in Gmax values.They are a ratio of the maximum acceleration experienced during an impact (known as deceleration), next to the normal rate of acceleration due to gravity. No section of the field should yield a score higher than 165 G’s or lower than 80. This is the standard set by the the Synthetic Turf Council. Ultimately, you want a lower score. The higher the Gmax value, the less force is being absorbed by the field. This means more force is returned to the player, which increases the likelihood of injury. Too low and the athlete is not getting ultimate agility results due to a surface that is too soft. For these reasons, Gmax testing should be a part of regular turf field maintenance.

It is important to understand how final data is compiled. Final Gmax scores are calculated by averaging the scores of each test location. Your artificial turf field could actually pass inspection even if parts are unacceptable. This is more common than you might think too. Areas receiving a lot of play could have a high Gmax score, while really soft areas like sidelines could yield low numbers. Averaging these locations with parts of the field scoring higher could generate a passing Gmax score.

The Purpose of Gmax Testing

Safety is the long answer in regards to Gmax safety. Unsafe fields could result in both upper and lower body injuries. Fields that are too hard negate safety features associated with turf cleats. Lower extremity injuries become a real possibility. However, Gmax tests are ultimately concerned with upper body safety. Concussion safety is part of the equation, but Gmax tests really revolve around broken bones and skull fractures.

This is why Gmax tests are one of several different methods used to gauge field safety. Even though skull fractures are the focus of Gmax tests, the flat cylindrical weight best replicates an individual’s torso hitting the ground. HIC (Head Injury Criterion) tests are recommended for getting a truer picture of what it’s like when a person’s head hits the ground. Similar to a Gmax test, the missile used is pointed to more accurately recreate the conditions of a person’s skull impacting the turf. The two tests together create a clear data which tell a true story concerning the condition of your field.

How Often Should a Gmax Test be Performed?

Gmax tests are merely snapshots. They are not static. As fields age, tests results will vary. For artificial turf, Gmax scores invariably increase. The amount of increase, however, is tied to the following factors:

• The Age of the Field
• Frequency of use
• Environmental Factors
• Method of Construction
• Types of Material Used
• Maintenance Schedule

These factors highlight the importance of Gmax testing, but how often is necessary? General consensus agrees every field should be tested just after install, before it is accepted for use. Beyond that, advocates suggest testing twice per year. The best advice is to follow the advice of researchers and industry experts. Their recommendation is at least once per year.

What a Gmax Test Means to You

Safety is a concern for everyone. This is why artificial turf Gmax testing is important no matter who you are. For instance, if you are a field manager, Gmax testing limits liability. This is particularly true if you have certain compliance standards to keep. Athletic directors have “duty of care” obligations for their players. Part of your obligation is to make sure the field is safe and properly maintained. Parents should be concerned as well. Honestly, you should know whether or not a field has been tested regularly in accordance with accepted safety standards and guidelines. Gmax tests are important to everyone.

Artificial Grass Pros Can Help

If you need a Gmax test or have questions about your artificial turf field, Artificial Grass Pros can help. We have hundreds of residential and commercial installs under our belt. So if your turf field needs an inspection, or maintenance to continue its warranty, give us a call. We offer a variety of turf maintenance services designed to keep your athletic field looking and performing its best.