Sport turf safety comes down to two things that have nothing to do with how the turf looks: G-Max and infill. Here’s what they actually measure, and why they matter more than the blade shape.
G-Max: how hard the surface actually is
G-Max is the official measurement of how much impact a surface absorbs, tested under ASTM F1936. A field can look identical to another and test completely differently underneath. The standard’s own ceiling for a field to be considered playable is a G-Max reading no higher than 200 at any test point, but that number is a hard limit, not a target. Synthetic turf performing well ideally lands between 90 and 115, in the range of natural grass. A reading pushing toward 200 is a real injury risk, not just a comfort issue, particularly for the kind of repeated impact a sport court sees that a landscape lawn never does.
G-Max isn’t fixed at the factory. It’s a function of the turf system as installed: the fiber, the infill, and the base underneath it together, not the turf alone. That’s why the base and infill matter as much as the blade itself for a surface meant for actual play.
Infill: what’s actually doing the shock absorption
Infill is the material worked down into the turf fibers, and it’s doing more of the safety work than most buyers assume. A few types exist:
Crumb rubber. The traditional choice, effective for shock absorption, though it retains heat in direct sun more than some alternatives.
Coated silica sand. Runs cooler and drains well, commonly paired with a resilient pad underneath rather than relying on the sand alone for shock absorption.
TPE and organic/cork blends. Newer alternatives built to reduce heat retention while keeping G-Max in a safe range, at a higher material cost than crumb rubber.
The right choice depends on the sport, the climate, and how the field is used, which is exactly why infill and application rate get specified per project rather than defaulted to one type across every install.
What this means for a backyard sport court
A dedicated sport surface, whether it’s a full field or a defined section of a yard, isn’t the same engineering problem as a landscape lawn. The base, the infill, and the fiber are chosen together around how the space actually gets used: cleats and repeated impact, not foot traffic in bare feet. Our Pro Blade is built with a shorter, thinner profile specifically for that kind of repeated footfall, and our sport field systems get their base and infill specified per project rather than reused from a residential install.
Request a free design consultation to talk through what a safe, properly specified sport surface looks like for your space.
Sources: ASTM F1936 impact attenuation standard, ASTM International; G-Max impact testing, Firefly Sports Testing.