New research from the Department of Kinesiology and Sport Sciences (KSS) challenges the effectiveness of a common football helmet add-on. Assistant Professor of Athletic Training Aaron Sinnott, Ph.D., ATC, and his team published their findings in the November 2025 issue of Medicine & Science in Sports & Exercise.
The study investigated whether the Guardian Cap mitigates head impact severity in college football players, contributing to emerging evidence that questions the device's protective benefits.
The team tracked 54 college football players from two institutions over one season using instrumented mouthguards, analyzing over 7,500 head impacts from practices and games.
The research concluded that the Guardian Cap had no significant effect on head impact magnitude (severity) or overall impact frequency.
“The Guardian Cap had no on-field effect on head impact magnitude or frequency,” the authors state. “However, the differing impact location patterns between wearers and non-wearers suggest the cap could influence how players use their heads during collisions.”
Although the cap did not reduce severity, the data revealed a significant shift in where impacts occurred. Players wearing the Guardian Cap experienced 36.2% lower odds of a facemask impact and 151.6% greater odds of an impact to the rear of the head.
Dr. Sinnott's team theorizes that the cap's design, which covers the shell but not the facemask, might subconsciously encourage players to make contact with the padded areas.
These findings underscore the urgent need for more randomized clinical trials to accurately inform football equipment policies and ensure player safety remains the top priority.
