WSAW (Madison, WI)
February 12, 2025
A study of 2,610 Wisconsin high school football players found that wearing soft-shell helmet covers, marketed as Guardian Cap helmet devices, during practice had no effect on the rates of sports-related concussions.
The University of Wisconsin School of Medicine and Public Health says a very important note is this study cannot be generalized to the NFL, because pro and college players wear a different, thicker model of Guardian Cap, and its results only look at high school football players. Additionally, this is one of very few studies to evaluate how the caps perform in real-world conditions.
“Unfortunately, we found that using these devices may provide false reassurance to players and their parents who are hoping to reduce their kids’ risk of concussion,” Dr. Erin Hammer, the study’s lead author and assistant professor of orthopedics and rehabilitation at the University of Wisconsin School of Medicine and Public Health, said.
The British Journal of Sports Medicine published the study last week.
The research team followed players from 41 Wisconsin high school teams during the 2023 football season. Individual teams decided who would wear the caps. Some of the players wore the Football Guardian Cap XT during practice and some never wore them. The caps were not worn during games.
Upon comparing concussion rates between the 1,188 players who did not wear Guardian Caps during practice and the 1,451 players who did, researchers found no statistical difference between the groups.
Of the 64 concussions sustained during practice, 33 happened to players wearing Guardian Caps, and 31 to those in the group without caps.
Head injuries were assessed by the team’s athletic trainers, who also kept track of helmet models, cap use, and the number of times a player practiced or played in a football game.
Data analysis showed other factors had no bearing on concussion risk during the study, such as whether the players had experienced previous concussions, the brand of helmet they wore, years of tackle football experience, or whether the playing surface was artificial turf or grass.
Researchers observed nearly eight times more sports-related concussions during practices among female football players than male, but noted that the small number of female players in the study–three total–limited generalizing the finding.
Previous lab tests suggested the extra padding in Guardian Caps could reduce force to the head during impact.
Using a large sample size, Hammer’s study assessed real-world concussion rate differences between groups of players using the caps and not using the caps. She cautioned that the study cannot be generalized to collegiate and professional league levels of football, however, because those players wear a different, thicker model of the device.
The researchers advise that high school teams implement data-backed interventions to reduce sports-related head injury rates, such as employing athletic trainers and supporting rule changes to limit contact during practice. These interventions have been shown to reduce sports-related concussions by 64 percent.
Additional risk reduction measures include training coaches in football safety, which cut concussion rates in half, and adding extra jaw padding to the helmets, which lowered rates by 31 percent.
“Given the size of our study, it seems that if Guardian Caps did protect against sports-related concussions in high school players, we would have seen that result,” Hammer stated.
The study was funded by a pilot award program at the Department of Orthopedics and Rehabilitation.