[Paper Review] Preliminary Examination of Guardian Cap Head Impact Data Using Instrumented Mouthguards

Kristen G. Quigley, Dustin Hopfe+5 more|arXiv (Cornell University)|Feb 21, 2023

Traumatic Brain Injury Research4 citations

TL;DR

This study evaluates the effectiveness of Guardian Caps (GCs) in reducing head impact severity among NCAA Division I football players using instrumented mouthguards (iMMs) during pre-season practices. Despite wearing GCs, no significant reduction was found in peak linear acceleration (16.3G vs. 17.2G), peak angular acceleration (992.1 vs. 1029.4 rad/s²), or total impacts (9.3 vs. 9.7), suggesting GCs do not mitigate head impact magnitude in this population.

ABSTRACT

Purpose The objective of this study is to present preliminary on-field head kinematics data for NCAA Division I American football players through closely matched pre-season workouts both with and without Guardian Caps (GCs). Methods 42 NCAA Division I American football players wore instrumented mouthguards (iMMs) for 6 closely matched workouts, 3 in traditional helmets (PRE) and 3 with GCs (POST) affixed to the exterior of their helmets. This includes 7 players who had consistent data through all workouts. Results There was no significant difference between the collapsed mean values for the entire sample between PRE and POST for peak linear acceleration (PLA) (PRE=16.3, POST=17.2Gs; p=0.20), Peak Angular Acceleration (PAA) (PRE=992.1, POST=1029.4rad/s2; p=0.51 and the total amount of impacts (PRE=9.3, POST=9.7; p=0.72). Similarly, no difference was observed between PRE and POST for PLA (PRE=16.1, POST=17.2Gs; p=0.32), PAA (PRE=951.2, POST=1038.0rad/s2; p=0.29 and total impacts (PRE=9.6, POST=9.7; p=0.32) between sessions for the 7 repeated players. Conclusion These data suggest no difference in head kinematics data (PLA, PAA and total impacts) when GCs are worn. This study suggests GCs are not effective in reducing the magnitude of head impacts experienced by NCAA Division I American football players.

Motivation & Objective

• To evaluate the effect of Guardian Caps (GCs) on head impact kinematics in NCAA Division I football players during on-field practice.
• To compare head impact metrics—peak linear acceleration (PLA), peak angular acceleration (PAA), and total impacts—between traditional helmets and GC-equipped helmets.
• To assess whether GCs reduce the magnitude or frequency of head impacts during closely matched pre-season workouts.
• To determine if GCs provide a measurable protective benefit in real-world collegiate football settings.

Proposed method

• 42 NCAA Division I football players wore instrumented mouthguards (iMMs) during six closely matched pre-season practices.
• Three practices were conducted with traditional helmets (PRE), and three with Guardian Caps affixed to the exterior of helmets (POST).
• Head impact data, including peak linear and angular accelerations and total impact counts, were collected and compared across conditions.
• Data were analyzed for the full cohort and for a subset of 7 players with consistent data across all sessions.
• Statistical comparisons (p-values) were used to assess significance between PRE and POST conditions for each metric.
• The study used a within-subjects design to control for individual variability and practice-specific factors.

Experimental results

Research questions

• RQ1 Does the use of Guardian Caps reduce peak linear acceleration during head impacts in NCAA Division I football players?
• RQ2 Does the use of Guardian Caps reduce peak angular acceleration during head impacts in NCAA Division I football players?
• RQ3 Is there a significant difference in the total number of head impacts between traditional helmets and Guardian Cap-equipped helmets?
• RQ4 Do individual players show consistent changes in impact metrics when switching from traditional helmets to Guardian Caps?

Key findings

• There was no significant difference in peak linear acceleration (PLA) between PRE (16.3G) and POST (17.2G) conditions (p = 0.20).
• No significant difference was observed in peak angular acceleration (PAA) between PRE (992.1 rad/s²) and POST (1029.4 rad/s²) (p = 0.51).
• The total number of impacts was nearly identical between PRE (9.3) and POST (9.7), with no significant difference (p = 0.72).
• For the 7 players with consistent data across all sessions, PLA (16.1G vs. 17.2G), PAA (951.2 rad/s² vs. 1038.0 rad/s²), and total impacts (9.6 vs. 9.7) showed no significant changes (p = 0.32, p = 0.29, p = 0.32 respectively).
• The study found no measurable reduction in head impact magnitude or frequency when Guardian Caps were used.
• These results suggest that Guardian Caps do not effectively reduce head impact severity in NCAA Division I football players under real-game-like training conditions.