Slit film turf is the most injury-prone playing surface in professional football. Data from the NFL shows it produces the highest rate of lower extremity injuries, non-contact injuries, and missed-time injuries compared to every other surface type, including other forms of artificial turf. The NFL Players Association has formally demanded its immediate removal and a permanent ban, calling it a workplace safety issue for the roughly seven teams still playing on it.
The problems go beyond joint injuries. Slit film surfaces trap heat at extreme levels, degrade in ways that worsen safety over time, and create biomechanical conditions that put unusual stress on ankles and knees. Here’s what makes this particular turf type so problematic.
What Slit Film Turf Actually Is
Slit film turf uses wider, flat ribbons of plastic that are slit (perforated) down the middle. This creates a web-like fiber that’s durable and holds up well under heavy foot traffic, which is why it’s been popular for high-use fields. But that durability is part of the problem: the fibers don’t give way or deform easily when a cleat digs in, creating a surface that grips footwear more aggressively than natural grass or newer synthetic alternatives like monofilament or dual-fiber systems.
Higher Injury Rates Across the Board
Research from Emory University analyzing NFL injury data found that slit film surfaces had the highest injury rate ratio of any surface type at 1.14, compared to natural grass as the baseline. The two major slit film products used in NFL stadiums, UBU/TurfNation and MomentumTurf, showed injury rate ratios of 1.33 and 1.31 respectively. When researchers grouped all surfaces into three categories (slit film artificial, other artificial, and natural grass), slit film came out on top with 1.49 injuries per team game, compared to 1.36 for other artificial surfaces.
A 2024 study published in the Orthopaedic Journal of Sports Medicine reinforced these findings. Across the 2021 and 2022 NFL seasons, lower extremity injuries occurred at a rate of 1.42 per game on artificial turf versus 1.22 on natural grass. More concerning, the odds of needing season-ending surgery were 60% higher on artificial turf than on grass. ACL reconstructions after turf injuries nearly doubled those after grass injuries: 30 versus 17 over the study period.
The NFLPA’s own analysis confirmed that slit film specifically produces statistically higher rates of non-contact injuries, lower extremity injuries, foot and ankle injuries, and injuries causing missed playing time compared to all other surfaces.
The Cleat Entrapment Problem
The core danger is rotational resistance, the force required to twist your foot free once a cleat is planted. On natural grass, soil gives way. Grass blades bend and roots release. On slit film turf, the rigid plastic fibers grip cleat blades tightly and don’t deform, which means the rotational force transfers directly into your ankle and knee instead of being absorbed by the surface.
Lab testing published in the American Journal of Engineering and Applied Sciences measured this torque directly. New slit film turf with only one inch of rubber infill produced 79.3 Newton-meters of rotational resistance. Adding more infill helped somewhat: 1.5 inches of rubber brought it down to 69.8 N-m. Even older, worn slit film turf still measured 54.2 N-m. For context, these forces are high enough that when combined with a sudden cut or change of direction, they can exceed what the ACL is designed to handle.
The type of cleat matters too. Bladed studs on new slit film turf without adequate infill create the worst combination, producing traction levels that cross from helpful into dangerous. Increasing the rubber infill depth reduces fiber contact and lowers torque, but too much infill changes ball behavior and playing characteristics, creating a tradeoff that field managers struggle to balance.
Extreme Surface Temperatures
Synthetic turf absorbs and retains far more heat than natural grass, and slit film is no exception. A systematic review of temperature studies found that synthetic grass surfaces routinely reach 50 to 75°C (122 to 167°F) in direct sunlight, while natural grass under the same conditions stays between 32 and 41°C (90 to 106°F). That’s a gap of 20 to 35°C on a typical summer day.
Some of the most striking measurements come from individual studies. Researchers recorded synthetic turf peaking at 74.6°C (166°F) while adjacent natural grass hit just 36.9°C (98°F). In summer months, synthetic surfaces ranged from 25 to 78°C, while grass stayed between 23 and 41°C. These temperatures are hot enough to cause skin burns on contact and significantly increase the risk of heat-related illness for athletes, particularly in outdoor stadiums during warm-weather months.
Air temperature above synthetic fields also rises measurably, typically 0.5 to 1.2°C higher than over grass. That small difference compounds with the radiant heat coming off the surface, creating a microclimate that makes the field feel substantially hotter than conditions in the stands or on the sidelines.
How the Surface Gets Worse With Age
Slit film fibers degrade with use, and there’s no way to prevent it entirely. Every interaction between a cleat and the surface causes microscopic damage. Over time, fibers elongate, split further, and eventually break. Research from the Norwegian University of Science and Technology found that higher strain rates from aggressive athletic movements accelerate this process, and that the combination of UV exposure, temperature swings, and heavy use hours compounds the deterioration.
As fibers break down, the playing surface becomes uneven. Ball roll and bounce become inconsistent, and the safety characteristics of the field change in ways that aren’t always visible. Infill levels shift as broken fiber fragments mix with the rubber granules, altering the cushioning and rotational resistance properties the field was designed to provide. Proper maintenance slows but doesn’t stop this process, and notably, researchers found no published studies on the long-term safety effects of fiber degradation, meaning fields may become progressively more dangerous in ways that aren’t being tracked.
The Push to Ban Slit Film in the NFL
As of the NFLPA’s public statement, seven NFL teams were still using slit film in their stadiums: the New York Giants, New York Jets, Detroit Lions, Minnesota Vikings, New Orleans Saints, Indianapolis Colts, and Cincinnati Bengals. Player leadership sent a letter to the league demanding immediate removal of all slit film surfaces and a permanent ban on future installations, both in stadiums and at practice facilities.
The league’s response was not what players hoped for. The NFL refused to mandate an immediate change and also declined to commit to any future timeline for phasing out slit film. The NFLPA framed this as a fundamental workplace safety issue, arguing that the injury data is clear enough to act on now.
Replacing a turf surface isn’t cheap. For a standard football field, swapping just the turf carpet and infill typically costs $350,000 to $700,000 or more when the existing base layer is still in good condition. A full new installation runs $500,000 to over $1.5 million. For NFL franchises valued in the billions, though, these numbers are modest relative to the cost of losing players to preventable injuries.
How Slit Film Compares to Other Synthetics
Not all artificial turf carries the same risk. Newer systems using monofilament or dual-fiber designs have thinner, more flexible blades that release cleats more readily during rotation. The NFL injury data consistently shows slit film at the top of the risk scale, with other artificial surfaces falling between slit film and natural grass. This distinction matters because the conversation isn’t simply “turf versus grass.” Slit film is a specific, older technology that performs measurably worse than the synthetic alternatives that have replaced it in many venues.
FIFA’s Quality Programme for football turf requires laboratory and field testing before any surface earns certification, though their standards focus on third-generation systems with both sand and rubber infill rather than singling out fiber types by name. The broader trend in sports facility management is moving toward surfaces that can be tested and certified for specific rotational resistance ranges, rather than relying on older designs that were built primarily for durability rather than player safety.