- A recent study co-authored by the NFL’s chief medical officer found the benefits of Guardian Caps in reducing concussions are ‘uncertain.’
- The study concluded there was no significant difference in concussion rates from direct helmet shell impacts between players who wore the caps and those who did not.
- The NFL continues to mandate Guardian Caps during practices and touts their effectiveness in reducing concussions.
- Sales for Guardian Caps have surged since the NFL’s mandate, with over 500,000 athletes now wearing the product.
The NFL has been a powerful champion of Guardian Caps, the padded football helmet covers the league touts as an effective way to reduce concussions. And NFL commissioner Roger Goodell has made some of the boldest claims.
“It’s actually reduced concussions by 50%,’ Goodell said in 2023 during an appearance on the Stephen A. Smith Show.
At the annual league meetings in 2024, according to ESPN, Goodell said the Guardian Caps have been “very effective and reduced concussions by 52%.’’
But a study involving the NFL’s top medical official suggests otherwise.
A peer-reviewed paper published online in July provides analysis of the study of the concussion rate at NFL preseason practices from 2018 to 2023. It concluded that, when considering concussions caused by blows to the helmet shell, there was no significant difference in the rate of concussions between players who did and did not wear the Guardian Caps, according to a paper published by the American Journal of Sports Medicine.
The study also found the degree of benefits of Guardian Caps “uncertain.’’
The NFL has not publicly addressed the study, but it has continued to tout the benefits of the Guardian Caps beyond what the study suggests.
An article published on the NFL’s website in August states Guardian Caps “have driven” a significant reduction in concussions in practices – about 50% over the past two preseasons.
In September, Sills said at a webinar that the NFL found a “very striking effect’’ when players were required to wear the Guardian Caps and that concussions dropped 50% during preseason practices in 2022 and 2023.
The NFL requires its 1,700 players to wear Guardian Caps during practices unless they wear one of 10 helmets the league says offer equal or better protection. They caps are optional during games, and about a dozen players have worn them this year, according to manufacturer Guardian Sports.
Some players have complained the Guardian Caps, which weigh 11.9 ounces to 14 ounces depending on the size of the cap, are heavy and hot. It’s unclear what NFL players know about the study.
But as the league has promoted Guardian Caps, product sales have soared, according to Guardian Sports, a family-owned company in Georgia that invented the helmet covers.
The company said that more than 500,000 athletes wear Guardian Caps and that the number has surged by about 200,000 since the NFL in 2024 required all players to wear the helmet covers during practices. The official website for Guardian Sports features quotes attributed to NFL officials, including Goodell, citing the benefits of Guardian Caps.
Rise of the Guardian Caps
Once widely derided for their bulky design, Guardian Caps have gone from the ugly duckling to mini-celebrity. They’re featured in Madden 26, the most recent version of the popular football video game.
“Isn’t it crazy?’’ Erin Hanson, CEO of Guardian Sports, said in an interview with USA TODAY Sports.
It was 15 years ago when she cofounded the company with her husband, Lee. They were focused on protecting the young developing brain, Hanson said.
“Our son was playing football,’’ she said. “That’s how we started this whole business, and we really didn’t gain traction and acceptance until the NFL took an interest and the NCAA teams took an interest.’’
In 2017, the NFL held its first HeadHealthTECH Challenge, designed to encourage the development of protective equipment in areas such as head protection.
Guardian Caps won.
At that time, the caps were worn by about 70,000 athletes, about 15% of the total worn by athletes today, according to Guardian Sports figures.
After lab studies and experimentation, the NFL required Guardian Caps to be worn by certain position groups during the 2022 preseason. Later that year, the NFL announced a 50% drop in concussions for players who wore the caps in preseason practices. The league reported the same results in 2023.
Soon the NFL embraced what has become one of its most visible efforts to reduce concussions, and that simultaneously generated publicity for Guardian Caps.
Retail pricing is $70 to $85 per helmet, but average team pricing is $53 to $65 per helmet, according to Guardian Sports. Guardian Caps specially made for NFL players are not available to the general public.
Erin Hanson said sales surged in 2024 after the NFL ordered that all players wear the helmet covers during practices.
“Now that it’s become normalized,’ she said, “we’ll hear youth players say: ‘Oh, man. I want one of those. Those are so cool.’ ‘
Potential ‘reverberations’ of study
Caplan, the medical ethicist from NYU, said he believes the study’s findings transcend the NFL.
“This has a much bigger footprint, given obvious parental worries about high school and younger kids playing tackle football,’ he said. ‘So the reverberations, in terms of how the NFL spins this, are going to be very big. And I hope they spin it in a responsible manner, not just leading with that headline of 50% reduction.’’
A study of 2,610 high school football players in Wisconsin showed Guardian Cap use was not associated with a decreased risk of sports-related concussions, according to its peer-reviewed findings published in January in the British Journal of Sports.
“My biggest concern is the downstream effect of the NFL being so firm in their conclusion that Guardian Caps work, because high schools don’t have a ton of money,’ said Erin Hammer, lead author of the study and a primary-care sports physician at UW Health medicine at the University of Wisconsin. “And if they’re spending money on Guardian Caps, they’re not spending it on resources that actually do keep kids safe, like hiring athletic trainers. So that is my biggest concern with any of these devices is that you’re allowing parents, athletes, school administrators to have faith in a device that may or may not work and purchase those in lieu of investing in resources that actually do keep kids safe.’
Sills stresses that the NFL uses an advanced model of the Guardian Cap that shows the clearest benefits and offered a strong endorsment of the cap in general.
“If I had a child who was currently playing football at the youth, high school, college or pro level, I would want him to wear a Guardian Cap as well,’’ Sills said, adding, “We’ve not seen any downside.’’
Next step for Guardian Caps study?
In 2023, at an NFL media briefing on health and safety, Sills, the NFL’s top medical officer, said the following: Concussions among players required to wear Guardian Caps during the 2022 and 2023 preseason practices dropped by about 50% compared with the preseason average from the previous three years.
He called the benefit “substantial.’’ The study published in July that lists Sills among its authors indicates otherwise.
Yet in September, Sills said during a webinar that the NFL found a “very striking effect’ when players were required to wear the Guardian Caps and concussions dropped 50% during preseason practices in 2022 and 2023.
Sills, a neurosurgeon, did not explain why the league has failed to address the analysis publicly. He reasserted his belief in the Guardian Caps and traced it back to lab studies he said revealed that the caps, when added to a standard NFL helmet, reduce the force by 10% to 15% anytime the helmet is contacted and by 20% to 30% if two players wearing Guardian Caps collide.
But Daniel Daneshvar, chief of the Division of Brain Injury Rehabilitation at Harvard Medical School, said it has never been safer to play football in the NFL based on head health. He cited improved helmets and the league’s new kickoff rules as ways the NFL has addressed head impact.
Regarding the Guardian Caps, Daneshvar questioned the reliability of lab studies, which used helmeted test dummies as opposed to real football players.
He said the lab tests rely on linear forces, measured when a helmet directly hits a hard object. What’s just as important, Daneshvar added, are rotational forces, measured by objects ‘glancing and bouncing and hitting indirectly off one another. Those are all factors that matter.”
“A football game is not a lab test,’’ said Daneshvar, a member of the Mackey-White Health and Safety Committee established by the NFL Players Association. “There’s a lot of ways that the lab data doesn’t translate necessarily to the real world.’’
He suggested taking the study out of the lab and onto the football field.
“If they really think the Guardian Caps are reducing the force of these impacts, then prove it,” Daneshvar said. ‘The forces transmitted past the helmet can be measured with mouth sensors or helmet sensors. The force of collisions can be estimated based on videos. So they could show data that there’s actually a reduction in forces to the head in response to similar impacts in the real world. It wouldn’t be that difficult.’’
But Sills said there’s already reason for optimism because the study shows concussion rates from preseason practices from 2018 to 2023 decreased from 23.3 concussions a year to 11.0 a year.
‘If we change something about your diet or your daily habit and there’s a 50% improvement in your blood pressure, elevated blood pressure, and that was across a large population, that’s a pretty dramatic effect,’’ Sills told USA TODAY Sports. “As a doctor, you would endorse that.
“So that’s kind of the policy side of it in the NFL and why we have continued to recommend the Guardian Caps. And … what I’ve said publicly is it’s been an unqualified success for us because we’ve not seen any downside.’
‘Personal choice’
At times, Guardian Caps have changed the narrative around concussions.
In 2022, Miami Dolphins quarterback Tua Tagovailoa suffered three concussions in three weeks. The NFL faced scrutiny about how the league managed players after they’ve been concussed.
In 2024, Tagovailoa suffered yet another concussion. Now he faced scrutiny.
Will you wear a Guardian Cap? a reporter asked.
“Nope,’ he replied.
Why?
“Personal choice,’’ Tagovailoa said.
Debate ensued.
‘Give Tua Tagovailoa a break on the Guardian Cap,’ Chris Nowinski, cofounder of the Concussion Legacy Foundation, posted on X. “All 3 of his 2022 concussions were from falling back & his head striking the ground. Adding 14 ounces to his helmet would make head-to-ground impacts even more likely. Better off never hitting the ground vs. hitting it with a pad.’
At the time, there was no peer-reviewed data from a field-based study assessing the benefits of the Guardian Cap.
Now there is.
Kristy Aborgast, a biomechanical engineer and member of the NFL Engineering Committee designed to advance the development of protective equipment, helped lead the study that showed preseason practice concussion counts dropped 53% for players required to wear Guardian Caps.
“But if you then limit the data to only those concussions where the impact was to the (Guardian Cap) shell, that statistical significance goes away,’ she said.
The study helped spotlight the importance of smarter players who have better technique and overall awareness of reducing head impacts.
“There’s all kinds of other levers that are at play here beyond just putting a padding over a helmet,’ she said. “But we estimated that about half the drop was due to the Guardian Cap itself.’
Still, adoption of the helmet covers isn’t widespread in the NFL’s main weekly showcase. Tagovailoa still isn’t wearing a Guardian Cap during games.
Neither are more than 99% of the NFL’s other players.
(This story has a correction: Allen Sills, the NFL’s chief medical officer, is a neurosurgeon.)