Guardian Caps at Every Position: What the Data Shows 

When the NFL began requiring certain positions to wear Guardian Caps during preseason practices in 2022, it created a large-scale, real-world test of Guardian Caps' effectiveness. The results – along with independent laboratory research – definitively show the reduction in impact and concussions amongst the players in these positions.  

But the research also demonstrates that the increased protection clearly extends to every additional player wearing a Cap – even those in positions not required to wear them.  

The NFL data: 54–62% fewer concussions 

A 2025 study published in The American Journal of Sports Medicine analyzed concussion data from more than 213,000 NFL preseason player practices between 2018 and 2023.¹ Among players in required positions, the concussion rate fell 54% after the requirement took effect, and 62% after controlling for position, year, and practice intensity. 

When running backs and fullbacks were added to the requirement in 2023, their preseason concussions fell as well, from an average of 2.75 concussions per year down to one. 

Over the same period, players in positions not covered by the requirement saw no improvement. The covered group improved substantially; the uncovered group did not, experiencing no reduction in concussions. 

Protection Compounds When Both Players Wear Caps 

Laboratory testing points to a dimension of Guardian Cap performance that position-based mandates don’t fully capture: Caps protect both sides of a collision. 

In 2024, Virginia Tech ran 240 impact tests on Guardian Caps using its established varsity helmet testing protocol.² With one player wearing a Guardian Cap, measured concussion risk dropped 15.5% with the XT and 34.1% with the NXT. When both players in a collision wore one, those reductions became 21.8% and 62.8% – nearly double.  

The NFL study’s authors noted the same principle. Citing Newton’s third law, they wrote that the Guardian Cap should benefit not only the player wearing it, but also the player who strikes it.¹ Their pilot testing likewise showed that a second cap roughly doubled the reduction in head impact severity. 

A player’s protection in any collision depends partly on what the other player is wearing. The more players wearing caps, the more collisions occur between two padded surfaces rather than one. 

The Bottom Line 

The strongest field data available shows a 54–62% reduction in practice concussions among players required to wear Guardian Caps. Laboratory testing shows the protection roughly doubles when both players in a collision wear one.  

Concussions occur at every position – and every additional player wearing a cap makes every collision they're part of more protected, for both players involved. 

Sources 

1. Funk JR, Cormier JM, Lessley DJ, et al. An Analysis of Guardian Cap Use and Changes in the Concussion Rate in National Football League Preseason Practices From 2018 to 2023. Am J Sports Med. 2025. doi:10.1177/03635465251351288 

2. Virginia Tech Helmet Lab. Football Helmet Shell Add-On Testing. 2024. https://www.helmet.beam.vt.edu/football-helmet-addons.html 

*The NFL's conclusion is based on a qualified study that evaluated Guardian Caps NXT alongside additional protective measures, which collectively contributed to a reduction in concussions. 

About Guardian Sports

Founded in 2010, Guardian Sports is on a mission to better protect athletes at every level of play. Its flagship product, the Guardian Cap, was originally developed to reduce head impacts during football practice and has since expanded into game-day use across all levels of play. Guardian Sports also created the LOOP flag football headband, PEARL lacrosse balls, FLEX chinstrap, and bio-based turf INFILL. Trusted by athletes nationwide, Guardian continues to lead in safety-driven innovation.