February 7, 2025
Imagine wrapping a fragile glass in bubble wrap before placing it inside a box. If the box is dropped, the bubble wrap absorbs some of the impact.
That’s essentially how Guardian Caps, the padded helmet coverings that have dominated football fields as one of the most recognizable safety measures in the sport, are designed to work. The soft shell absorbs some of the initial force from helmet-to-helmet contact, reducing the direct shock transferred to a player’s helmet. And because the cap moves slightly upon impact, it helps dissipate the rotational forces that contribute to brain injuries.
But while Guardian Caps aim to address the immediate impact of these hits, they also serve as a symbol of a broader response to a much larger concern: chronic traumatic encephalopathy, also known as CTE. The neurodegenerative disease is linked to repetitive hits to the head, including those known as subconcussive hits.
Some of the life-altering symptoms of CTE include memory loss, mood swings and cognitive decline. Research has shown that years of repetitive head impacts can cause significant neurological deterioration, even in players without ever having a single diagnosed concussion.
The dangers of the disease have fueled a race to find preventive solutions across all levels of the sport. Guardian Caps have emerged as a centerpiece of this effort, which the company claims can reduce head impacts by up to 30%.
But as their popularity grows, so do questions over whether Guardian Caps offer genuine protection or are only a Band-Aid fix to a much larger issue.
Guardian Caps first gained traction at the collegiate level, with South Carolina being the first to adopt them in 2012. All SEC schools have ordered Guardian Caps for their football teams to use since then. Missouri football gives its players the option to wear Guardian Caps in practices or games, a program spokesperson said. Missouri declined to share if any players have worn the caps in games, citing HIPAA.
Some NFL teams began to follow suit in 2022. A mix of the product’s rising popularity and increasing scrutiny over the dangers of the game led to the NFL mandating that players at certain positions wear Guardian Caps during contact practices in 2023. In spring 2024, the league expanded the requirement to include all positions with the option for quarterbacks, kickers and punters.
The padded coverings have quickly gained traction. In addition to the practice mandate, NFL players can elect to wear Guardian Caps during games. Sixteen players have done so this season, averaging six players per week, according to Guardian Sports.
The NFL had previously reported a 50% reduction in concussion rates among players that were required to wear them during practices.
The league reported 182 concussions during games and practices in both the preseason and regular 2024 season, a 17% drop from 2023. It’s the fewest number of concussions the NFL has reported since it began tracking them in 2015.
The protective gear isn’t just popular at the professional level. According to Guardian Sports’ website, Guardian Caps are also worn by players at over 500 colleges, 5,000 high schools and 1,000 youth programs. Adoption rates have soared, with over 500,000 caps having been distributed so far to players across all program levels: NFL, CFL, college, high school and youth. Locally, 65 high schools in Missouri have ordered Guardian Caps for their programs in the past two years, according to Guardian Sports records. In Columbia, the caps are not provided to players but some use them at Rock Bridge and Hickman high schools.
But not everyone agrees that Guardian Caps can serve as a solution to the long-term consequences that the sport can bring. Some researchers, neurologists and physical therapists argue that Guardian Caps cannot address the actual causes of CTE.
Becky Bliss, a neurological physical therapist at MU Health Care, said she doubts the effectiveness of Guardian Caps because, while they may soften external impacts, they cannot prevent the brain from shifting inside the skull upon contact.
“If I put a cap on the outside, that isn’t changing the brain sloshing in the skull. There is no piece of equipment that will prevent a concussion,” Bliss said.
In a 2025 study published in the British Journal of Sports Medicine, researchers analyzed data from over 2,600 athletes across 41 Wisconsin schools, comparing concussion rates between players who wore Guardian Caps during practices and those who did not. The study found that Guardian Cap use was not associated with a lower risk of sport-related concussions during practices or games.
While Guardian Caps have become a symbol of football’s push for safety, CEO Erin Hanson said the company has not overstated its role.
“We do not claim that we prevent concussions. We reduce the impact of all nonconcussive hits over the course of a player’s career,” Hanson said.
As Guardian Caps become more common on the field, the disagreement over their true effectiveness brings about bigger questions about how football is addressing, and sometimes avoiding, its long-standing issues with head traumas.
A fix or a false sense of security?
Despite their growth in popularity, research on the effectiveness of Guardian Caps is mixed. The long-term impact of subconcussive hits is still being studied, and the effectiveness of protective gear in preventing CTE remains uncertain.
Robert Stern, a neuropsychologist and co-founder and director of clinical research at the Boston University CTE Center, compares the brain to a bowl of jello. When the head gets hit, the brain shifts and shakes inside the skull, just like how jello does when a bowl is knocked. No external padding or helmet can fully prevent this internal movement, which is what can ultimately leads to repetitive brain trauma and later-life brain disease over time.
Stern said he is concerned that emphasizing solutions like Guardian Caps may divert attention from the broader issue at hand.
“The more we focus on concussions, the better it is for the life of the NFL, because concussions you can do something about,” Stern said. “What you can’t do in American football is remove tackling with the head being involved. … Even if it’s not direct, big hits, think of every play of every game and every practice. Most of the players are in some way rattling their brains.”
In laboratory testing, a Stanford study found that while Guardian Caps significantly reduce rotational forces, such as the twisting and spinning motions that contribute to brain injuries, their ability to reduce linear forces was not as statistically significant. In other words, the caps help limit the force of the hit by sliding around on the outside of the helmet, rather than through compression of the cap foam.
“It’s almost impossible for lab testing to replicate what’s happening during a game or practice, but teams using them year after year see the benefits,” Hanson said.
Bliss, who has worked in concussion rehabilitation for over 20 years, remains skeptical. She said that because Guardian Caps do not change how the brain moves inside the skull upon impact, they cannot be a reliable solution for CTE prevention.
“Everyone wants to find a solution, but we need to dive deep into the science to ensure these solutions actually work,” Bliss said.
The psychological impact of Guardian Caps is another growing concern among researchers. Some athletic trainers worry the protections players believe they offer could create a false sense of security, leading players to take greater risks on the field.
“Coaches tell us the caps act as a visual reminder to keep their heads up, improving technique rather than encouraging recklessness,” Hanson countered. She added that helmet damage in Guardian Caps can help coaches identify players who need technique adjustments, something that’s not as obvious with regular helmets.
“Some of the resistance against Guardian Caps is that people are hesitant to implement a safety device unless they know it’s 100% going to protect a player,” Hanson said. “Seatbelts don’t save 100% of lives, but if they can make an incremental difference, there’s value in it.”
Not a quick fix
Historically, football has struggled to balance safety with the nature of the game. Stern argues that the NFL’s focus on concussions has overshadowed the more significant issue: repetitive subconcussive hits.
“It’s not concussions that lead to CTE. It’s the repetitive hits, often unnoticed, that accumulate over time, causing long-term changes to the brain,” Stern said.
“Some linemen never had big hits or reported concussions, yet their brains showed significant evidence of CTE,” Stern added. “It’s the nature of the game, not the concussions, that’s the issue.”
Bliss emphasized that changing technique and culture rather than equipment is key to reducing head traumas, arguing that preventative measures beyond equipment should be getting more focus. Preseason neuromotor control exercises, neck strengthening drills and reaction time training are all practices that can help reduce concussion rates, she said.
“It’s about building resilience before injuries happen, not just responding after,” Bliss said.
A problem as old as the sport itself, the perfect solution to head traumas in football seems like it isn’t coming anytime soon. Some experts, including Stern and Bliss, agree that addressing the issue will require a combination of better research, cultural change and systemic reforms.
Stern said the ultimate change would be eliminating tackling from football altogether. For now, he calls for more longitudinal studies to fully understand the long-term effects of repetitive head impacts, a feat he is currently taking on himself. A major part of Stern’s research is developing methods of detecting and diagnosing CTE during life through various brain imaging techniques and blood tests.
Despite the skepticism, Hanson remains optimistic about Guardian Caps’ role in improving safety on the field.
“We’re committed to making the game safer while preserving what people love about it,” Hanson said.
Experts like Bliss and Stern believe no piece of equipment alone can solve football’s long-standing head injury crisis. Instead, a larger reform is needed.
“No piece of gear will ever eliminate risk,” Bliss said. “The question is, how do we make informed decisions that prioritize players’ health without losing the heart of the game?”