GMAX Compliance Checklist

A practical walkthrough for athletic directors: when to test, what the numbers mean, and what to do about a bad result.

GMAX testing measures how much impact energy a playing surface absorbs — it's the standard proxy for concussion and injury risk on athletic fields. A lower GMAX reading means the surface absorbs more impact; a higher reading means more of that impact energy transfers to the athlete. For a deeper explanation of the scoring itself, see What Does a GMAX Score Mean? This page is the compliance-planning side: what to actually do, and when.

Testing Frequency

  • Test at least annually for any field in regular athletic use
  • Test before the start of each major sport season if the field sees year-round multi-sport use
  • Test after any significant infill work, repair, or renovation
  • Test after severe weather events that could have compacted or displaced infill (hail, prolonged heavy rain, extreme heat)
  • Check your conference, UIL classification, and insurance carrier for any testing frequency they specifically require — this checklist is a general baseline, not a substitute for your governing body's rules

Reading the Score

  • Readings are typically taken at multiple points across the field, not just one location — a field can have localized problem areas even if the overall average looks fine
  • Most athletic programs treat a GMAX reading below 200g as within normal range
  • Readings approaching or exceeding 200g are generally flagged for corrective action
  • Readings approaching 300g are generally treated as a safety concern requiring prompt attention — check your specific governing body's threshold, as exact cutoffs vary by organization
  • A single high reading in one spot usually points to localized infill compaction; high readings across the whole field usually point to a broader infill or backing issue

Before Your Test

  • Confirm your tester is using a calibrated device and following ASTM F1936 (the standard test method for impact attenuation of turf playing systems) or your governing body's specified method
  • Have prior test results on hand for comparison — a trend matters more than a single data point
  • Note any recent weather events, heavy-use periods, or repairs since the last test
  • Identify known problem areas (goal mouths, high-traffic zones) so the tester can prioritize those points

After a High Reading: Corrective Actions

  • Infill redistribution or top-up in the affected area — often resolves localized compaction issues
  • Deep decompaction/aeration of the infill layer
  • Re-test the corrected area to confirm the reading has come back into range before returning the field to full use
  • If readings stay elevated after infill correction, the issue may be in the shock pad or backing — that's a bigger conversation about repair versus replacement, not a routine maintenance fix

Documentation to Keep on File

  • Dated GMAX test reports, including per-point readings, not just the average
  • Records of any corrective action taken after a flagged reading, and the re-test results confirming it was resolved
  • Testing method and equipment used (for insurance and liability purposes)
  • A running maintenance log — testing records are far more useful as evidence of due diligence when there's a documented maintenance history behind them

Need GMAX Testing Scheduled?

We provide certified GMAX testing alongside our maintenance services, with documentation you can keep on file for compliance and insurance purposes.

Learn About Our GMAX Testing Call (469) 981-9247