The NFL regular season has kicked off, and loyal viewers might notice a new addition to some players’ helmets: a layer of padding.
Players first started wearing a protective cover on their helmets, known as a Guardian Cap, during training camps in the 2022 season. However, in 2023, the NFL mandated that most players wear them during practice and, more recently, has given players permission to wear them during games.
The idea is that the extra cushioning can absorb some of the impact of a collision, reducing head injuries.
Indianapolis Colts tight end Kylen Granson plans to wear a Guardian Cap this season, as he explained in a TikTok video that has racked up nearly 700,000 likes.
“For me, it was a no-brainer; I just said, ‘Yes, I want to wear it the whole season,’” he said. “Why would I not add a safety measure to a helmet?”
Here’s what to know about Guardian Caps, including what research suggests about their effectiveness.
What Is a Guardian Cap?
Guardian Caps are manufactured by Guardian Sports, one of many companies developing products with extra padding added atop or inside helmets.
The Guardian Cap NXT model, which NFL players use, is made of closed-cell foam and covered by spandex fabric, according to the company’s website.
Guardian Sports says the product “reduces the impact of constant hits in practice,” though it does not claim that Guardian Caps can conclusively lower the risk of a concussion.
Football, like other high-contact sports such as hockey and soccer, “involves high-impact repetitive trauma, which increases the risk for sub-concussive blows and concussion,” Seth Jenny, PhD, an associate professor of exercise science at Slippery Rock University of Pennsylvania, told Health.
A 2017 study that looked at 202 brains from professional football players post-mortem found that 87% had signs of the brain disorder chronic traumatic encephalopathy, or CTE, which can cause cognitive issues, learning problems, depression, anxiety, suicidal ideation, and eventual dementia.
According to the manufacturer, Guardian Caps are worn by players from thousands of high schools and hundreds of colleges and youth programs, in addition to NFL players.
What the Research Suggests About Guardian Caps
It’s unclear whether Guardian Caps really “reduce harm” on the field, as Guardian Sports suggests.
The NFL asserts that players wearing Guardian Caps during practice in the last two seasons have seen a 52% decrease in concussions, but CNN reported that the research hasn’t been published or shared with outside researchers.
Erik Swartz, PhD, vice dean and professor at Adelphi University’s Ruth S. Ammon College of Education and Health Sciences, told Health that the NFL’s statistic is “potentially misleading” because any shifts in concussion rates between seasons could be due to other changes the league has implemented.
Swartz was the first author of a National Athletic Trainers’ Association 2022 position statement that cautioned against helmet add-ons, saying that they could instill a false sense of security and lead to riskier behavior on the field. “The current evidence describes no benefit” of helmet add-ons, the authors wrote.
As for Guardian Caps, “the evidence is mixed on the effectiveness of using” them “to reduce the force of impact in football to increase player safety,” Jenny said.
In 2017, he and other researchers surveyed 380 youth and high school football coaches, athletic directors, and presidents about using Guardian Caps. The team found that, on average, the 37 people who completed the survey reported a 40.5% decrease in yearly concussions after transitioning to using Guardian Caps.
Another study out of the Virginia Tech Helmet Lab, which hasn’t been published in a peer-reviewed journal, found that Guardian Caps reduce the force of a helmet-to-helmet impact, especially with thicker models used by the NFL and when both players wear them.
But Swartz said you can’t assume that results from a lab would translate on the field. “I know that sounds like it would be logical, but it’s not really that simple,” he said. “If you take an impact to your head from a force, what you sustain from the impact is related to the velocity of the impact, the mass that impacted you, and the physics of it.”
Studies that have examined Guardian Caps’ effectiveness in real-world situations suggest that the helmet shells have little effect.
One study from 2023, for example, looked at 25 Division I college players across six practices, where players wore Guardian Caps during three sessions. “We compared practices where athletes use Guardian caps and practices where they didn’t,” Kristen G. Quigley, lead author and a PhD student at the University of Nevada, Reno, told Health. Ultimately, “there was no difference in head impact kinematic data,” she said.
Another study from that year found no differences in protective effects for college players who wore and didn’t wear Guardian caps.
When it comes down to it, we simply need more information about Guardian Caps to know whether they will truly protect players, Steven Broglio, PhD, director of the University of Michigan Concussion Center and an author of the NATA statement, told Health. “I want it to work,” he said, “but I want to see the data before I say for sure it’s working.”