Guardian Caps — Do They Work?

[Bobref]

Not surprisingly, after the NFL declared that their experiment with Guardian caps showed a significant reduction in concussions, some real scientists decided to employ some real scientific testing to check the accuracy of the claims. Turns out that large scale studies have shown no reduction in concussion rates through the use of Guardian Caps. In addition to the study cited below, other large studies at the University of Wisconsin, and at Ball State, reached the same conclusion.

https://www.concussionalliance.org/blog/guardian-caps-do-not-reduce-the-risk-of-srcs-in-high-school-football-players

XT Guardian Caps do not reduce the risk of sport-related concussions in high school football players

By Anni Yurcisin. This article was initially published in the 11/6/25 edition of our Concussion Update newsletter; please consider subscribing.

In the East Bay in California, several high school football players sustained a concussion in one Friday night game, with one player having to be wheeled off on a stretcher, according to an NBC Bay Area article by Pete Suratos. Parents struggled with watching their kids get injured, looked for a lifeline to prevent concussions, and decided on Guardian Caps. Although they haven’t been proven to reduce concussions in high school football players, parents have been raising money to buy one for every player.

A recent study in the British Journal of Sports Medicine found that Guardian Caps (GCs), an add-on padded “shell device” that goes atop a helmet, do not reduce the risk of sport-related concussions (SRCs) in high school football players. Across more than 2600 high school football players, GC use during practice was not associated with decreased SRC risk in practices or in games, including when accounting for the increased risk factor of having sustained an SRC in the past. While laboratory experiments have shown that extra padding, such as GCs, can limit simulated head impact forces, and previous data from the NFL have shown a decrease in preseason concussions with GC use, no previous studies have looked at the real-world efficacy of high school GCs, which, notably, are a different model from those used in the NFL. The GCs worn in the NFL (the NXT model) weigh approximately 357 grams and are approximately 2.5 cm thick, while those worn by high schoolers (the XT model) weigh approximately 220 grams and are approximately 1.5 cm thick. Because of this difference, NFL studies cannot be extrapolated to high school athletes. This study illustrates that there is no evidence to suggest that the XT model GCs used by high school athletes reduce SRCs. Importantly, as Dr. Erin Hammer told the UW-Madison School of Medicine and Public Health, “... using these devices may provide false reassurance to players and their parents who are hoping to reduce their kids’ risk of concussion.”

Of the 180 SRCs recorded throughout the year by athletic trainers, 64 occurred during practice and 116 occurred during games. The number of SRCs occurring in practice was remarkably similar between GC-wearing and non-GC-wearing athletes; 33 of the practice-related concussions were in athletes wearing GCs, while 31 practice-related concussions were in athletes not wearing GCs. In what is standard practice among football players who wear GCs, athletes who wore GCs during practices did not wear them during games. Of the 116 game-related concussions, 68 occurred in athletes who wear GCs at practice, and 48 occurred in those who do not.

The authors urge sport-related institutions to implement evidence-based changes to reduce SRCs rather than pursuing new technologies that haven’t been proven to reduce SRCs in non-laboratory settings, such as GCs. They highlight three changes that have been connected to a reduction in SRCs: policies aimed at limiting contact in football practices (which reduced the rate of practice-related SRCs by 64%), coach participation in a comprehensive football safety training program (which reduced the rate of practice and game-related SRCs by 50%), and modifications to helmets with increased padding in targeted areas (which were associated with a 31% lower rate of SRC). These changes, while less flashy than technologies like GCs, have been proven to decrease the risk of SRC and should be the targets for high school leagues to improve the cognitive health of their athletes

[Impartial_Observer]

So predictably these devices don’t pad the brain from the skull?

[Bobref]

8 hours ago, Impartial_Observer said:

So predictably these devices don’t pad the brain from the skull?

The laboratory data show a reduction in certain impact forces with the use of the caps. However, the studies show that, in the real world, that doesn’t translate to fewer concussions.

[Daniel_Bragg]

Is it not possible that both could be true?  NFL players collide A LOT harder and faster than high school players.  I could believe that they would cut down on concussions in the NFL, while having very little effect in the high school ranks.

[Bobref]

17 minutes ago, Daniel_Bragg said:

Is it not possible that both could be true?  NFL players collide A LOT harder and faster than high school players.  I could believe that they would cut down on concussions in the NFL, while having very little effect in the high school ranks.

The physics say the reverse should be true if NFL players wear the same Guardian caps as high school players. But they don’t. As the article points out, the differences in the caps prevent you from extrapolating NFL results to the high school situation.

I’m not a neurologist, but I speculate that it is also possible a teenager’s brain is not able to protect itself from impact as well as a fully mature adult brain. Just a guess.

Edited December 21, 2025 by Bobref

[Impartial_Observer]

56 minutes ago, Bobref said:

The physics say the reverse should be true if NFL players wear the same Guardian caps as high school players. But they don’t. As the article points out, the differences in the caps prevent you from extrapolating NFL results to the high school situation.

I’m not a neurologist, but I speculate that it is also possible a teenager’s brain is not able to protect itself from impact as well as a fully mature adult brain. Just a guess.

Or dare I state the obvious…..the NFL got the results they paid for?

[wabashalwaysfights]

11 hours ago, Impartial_Observer said:

Or dare I state the obvious…..the NFL got the results they paid for?

[First_Backer_Inside]

Just speaking from my experience with them at our high school, we have worn the guardian caps for practice only the last 2 years. Before this, a lot of our concussions were occuring during practice time and not games. The last two years, we haven't had a kid complain about their head hurting or anything like that during practice. We have still had kids get them from games. Usually if a kid complains about more than one happening, we tell the player they have to wear one during games as well. In my experience they work, or they at least give the players a sense of security they didn't have previous to them wearing one. Whatever the case, I will stand by the idea that they are helping more than I will stand by the idea that they are doing nothing.

[foxbat]

1 hour ago, First_Backer_Inside said:

Just speaking from my experience with them at our high school, we have worn the guardian caps for practice only the last 2 years. Before this, a lot of our concussions were occuring during practice time and not games. The last two years, we haven't had a kid complain about their head hurting or anything like that during practice. We have still had kids get them from games. Usually if a kid complains about more than one happening, we tell the player they have to wear one during games as well. In my experience they work, or they at least give the players a sense of security they didn't have previous to them wearing one. Whatever the case, I will stand by the idea that they are helping more than I will stand by the idea that they are doing nothing.

This is the part that worries me most with young kids.  It is incumbent on coaches to really drill home that these don't make you invincible or completely protect you; even if they do provide a layer of protection.  Good tackling technique as well as safe tackling technique needs to be drilled home again and again and again with kids.  And I would say this is particularly important at younger ages where sometimes you get what's available for youth coaches and sometimes something like this might be used as a substitute for safe procedure education and adherence. 

[Coach Nowlin]

Same Genre:  Equipment:

 

Perhaps our officials out here like @Bobref and @JustRules can help.  In the NFL/College game, is it still required to physically attach a mouth guard to helmets?    Its clear that this is not a forcible infractions of the NCAA/NFL, so is there a way to just say, they are in or not in, but no more fashion statements on these thing??  

While I am at and we are discussing this equipment and protections:  Good time to remind folks that the Knee injuries that have been occurring in the NCAA and NFL to players have had ZERO to do with a "pad" not being worn the size of a coaster for your Pepsi's .......     Be nice to see that get out of the Officials things they are constantly complained to by their suits to fix at the HS level

Seems like the state of Texas has survived last few years not regulating the length of the ones football pant

[Bobref]

16 hours ago, Coach Nowlin said:

Perhaps our officials out here like @Bobref and @JustRules can help.  In the NFL/College game, is it still required to physically attach a mouth guard to helmets?    Its clear that this is not a forcible infractions of the NCAA/NFL, so is there a way to just say, they are in or not in, but no more fashion statements on these thing??

Don’t know what the NFL rule is. And as far as college football, seems to me like pretty much anything goes. They take care of it quite easily under the IHSAA. If you don’t have one in your mouth, you don’t play. If you have one in your mouth and one dangling from your facemask, it’s considered an illegal uniform adornment, and it comes off or you are sent off the field.

[Coach Nowlin]

8 hours ago, Bobref said:

Don’t know what the NFL rule is. And as far as college football, seems to me like pretty much anything goes. They take care of it quite easily under the IHSAA. If you don’t have one in your mouth, you don’t play. If you have one in your mouth and one dangling from your facemask, it’s considered an illegal uniform adornment, and it comes off or you are sent off the field.

Well , yes, of course, however, one can ask a simple question, for all those athletes who are playing an incredible pace / speed/ strength.   I am just SHOCKED I do not see teeth just getting spit out left and right on the football field on Saturday and Sundays.    Crazy I tell ya 

[Bobref]

1 hour ago, Coach Nowlin said:

Well , yes, of course, however, one can ask a simple question, for all those athletes who are playing an incredible pace / speed/ strength.   I am just SHOCKED I do not see teeth just getting spit out left and right on the football field on Saturday and Sundays.    Crazy I tell ya 

There are studies which suggest properly fitted mouthguards reduce the incidence and/or severity of concussions, in addition to protecting teeth and jaws. Facemask sand visors have gotten pretty good at that.

[Coach Nowlin]

SO why is it required for some leagues and not others? 

Why is it not an issue in Texas but it is elsewhere? 

 

[JustRules]

6 hours ago, Coach Nowlin said:

SO why is it required for some leagues and not others? 

Why is it not an issue in Texas but it is elsewhere? 

 

It's supposed to be required in NCAA as well (and I assume NFL), but the latest fad is definitely having the dangling mouth piece. It used to be players who had a second one in their mouth and one either stuck in their face mask or dangling, but they gave up no the one in the mouth. Unfortunately the D1 guys are told to not be uniform police, so they rarely enforce anything uniform related. Nobody wants to see you send out Mendoza on a key 3rd down play because he failed to put in his mouthpiece before the previous snap. I don't agree with this, but we see it all the time. And small college and high school players are copy cats. The mouth piece is an easy one that should be enforced at all levels.

[Coach Nowlin]

and now you see the quagmire 

where is the leaders and stewards of the game......   

 

Mouthpiece I support, yes,   the pant police......yea.....   let focus on illegal formations and other things of that nature as I know the feedback I get from many guys is the same, wish they could worry more about more important stuff in the 48 min game then knee pads.  

 

[Impartial_Observer]

3 hours ago, Coach Nowlin said:

and now you see the quagmire 

where is the leaders and stewards of the game......   

 

Mouthpiece I support, yes,   the pant police......yea.....   let focus on illegal formations and other things of that nature as I know the feedback I get from many guys is the same, wish they could worry more about more important stuff in the 48 min game then knee pads.  

 

I’d be willing to bet the farm, you will not find an official in the state of Indiana who doesn’t agree 100% with that. 

[Bobref]

4 hours ago, Impartial_Observer said:

I’d be willing to bet the farm, you will not find an official in the state of Indiana who doesn’t agree 100% with that. 

The funny thing is, most of the people with the power to change that feel the same way. The IHSAA is a member institution. If the IFCA feels that strongly about it, go to the IHSAA’s Executive Committee and have them lean on the Commissioner. He works for them, after all. That no one has done that tells me it’s not really a big concern for most coaches.

[Sparty]

4 hours ago, Bobref said:

The funny thing is, most of the people with the power to change that feel the same way. The IHSAA is a member institution. If the IFCA feels that strongly about it, go to the IHSAA’s Executive Committee and have them lean on the Commissioner. He works for them, after all. That no one has done that tells me it’s not really a big concern for most coaches.

I wonder if they could do a zoom/remote meeting for all coaches to attend?   Not all coaches live in the donut area of Indy.  Drives can be long which adds on to all the other demands coaches have.  Now we can say, have the meeting on a Sunday.  Well that is usually the only day off most coaches have entirely with their families.  I think this would be the best way to get this done.  
And before you thank me for my contribution to this topic/thread, you are welcome @Bobref

Edited January 8 by Sparty

[Bobref]

37 minutes ago, Sparty said:

I wonder if they could do a zoom/remote meeting for all coaches to attend?   Not all coaches live in the donut area of Indy.  Drives can be long which adds on to all the other demands coaches have.  Now we can say, have the meeting on a Sunday.  Well that is usually the only day off most coaches have entirely with their families.  I think this would be the best way to get this done.  
And before you thank me for my contribution to this topic/thread, you are welcome @Bobref

The IFCA meeting in the Spring would be the place to start.