Efficacy of Guardian Cap Soft-Shell Padding on Head Impact Kinematics in American Football: Pilot Findings

Sinnott, A.M.; Chandler, M.C.; Van Dyke, C.; Mincberg, D.L.; Pinapaka, H.; Lauck, B.J.; Mihalik, J.P. Efficacy of Guardian Cap Soft-Shell Padding on Head Impact Kinematics in American Football: Pilot Findings.
Int. J. Environ. Res. Public Health 2023, 20, 6991.
DOI: https://doi.org/10.3390/ijerph20216991
Academic Editor: Britton W. Brewer.
Received: 6 September 2023
Revised: 23 October 2023
Accepted: 24 October 2023
Published: 28 October 2023
Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Aaron M. Sinnott
Madison C. Chandler
Charles Van Dyke
David L. Mincberg
Hari Pinapaka
Bradley J. Lauck
Jason P. Mihalik (Corresponding Author)
Affiliation: Matthew Gfeller Center, Department of Exercise and Sport Science, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA

Research Focus: Sport-related concussion prevention strategies in collision sports.
The study explores the effectiveness of after-market soft-shell padding, specifically the Guardian Cap, in reducing head impact severity during American football.

Compared head impact kinematics between athletes wearing Guardian Cap soft-shell padding (SHELL) and those without (CONTROL).
Participants: 10 Division I college football players
- SHELL group: 5 players (4 defensive linemen, 1 tight end)
- CONTROL group: 5 players (2 offensive linemen, 2 defensive linemen, 1 tight end)
Measurement of head impacts quantified linear (PLA) and rotational acceleration (PRA) during 14 practices.
Analysis of 968 video-confirmed head impacts (SHELL: 421; CONTROL: 547).

Observed no significant effect of the Guardian Cap on reducing head impact kinematic outcomes among athletes.

Concerns around short- and long-term risks associated with sport-related concussions and repetitive head impact exposure (RHIE) in contact sports.
Increased awareness has driven strategies to mitigate concussion risk and burdens from RHIE.
Equipment, particularly soft-shell padding, has been championed for its potential to lessen head impact severity across various sports, including rugby and soccer.

The Guardian Cap is added to a standard football helmet to reduce forces transmitted to the helmet.
The NFL mandated usage of the Guardian Cap during the 2022 preseason for specific position groups due to their higher RHIE.
Prior evidence suggested greater incidence of concussions and RHIE during the preseason, highlighting the need for preventive strategies.
A previous NFL report indicated a 50% reduction in concussion incidence post-mandate but largely from laboratory investigations.
Contrasting findings in the laboratory showed mixed results concerning impact severity reduction.

Prospective observational study during the 2022 competitive season focusing on full-contact practices.
A total of 10 Division I players (5 SHELL, 5 CONTROL) were studied.

SHELL Group:
- 4 defensive linemen, 1 tight end
- Average height: 195.4 ± 2.2 cm, mass: 125.6 ± 13.3 kg
CONTROL Group:
- 2 offensive linemen, 2 defensive linemen, 1 tight end
- Average height: 189.5 ± 5.5 cm, mass: 120.2 ± 8.3 kg

The Guardian Cap NXT consists of a dual-layer foam pad and can be secured to a standard helmet using buttons and Velcro for a snug fit.
Riddell Speed Flex helmets equipped with the Head Impact Telemetry (HIT) System, which includes accelerometers for capturing head impacts.

Timing of impacts recorded via sensors triggered upon detection of linear acceleration exceeding 9.6g.
Data sampled at 1000 Hz for subsequent analyses.
Video cameras recorded practice sessions for further analysis of head impacts.
Data processed included the category of the sustained impacts in tables for final analysis.

2,653 total impacts recorded, with 1,225 confirmed via video review.
Excluded specific events (helments-only practices, statistical outliers, etc.), leading to a final sample of 968 impacts for analyses.

No significant differences discovered between SHELL and CONTROL groups across various categories of metrics (helmets, direction, stances).

ANOVAs revealed both main effects and interactions regarding impact locations, showing various patterns between different stances, directions, and impact closures.

Notable findings indicated that, on average, the protective soft-shell padding did not lead to reduced head impacts in collegiate players.
Factors contributing to head impacts included gameplay characteristics, which should be considered in future investigations.
Emphasized the necessity for further exploration into various protective equipment and contextual factors influencing head impact severity.
Supported by previous findings and literature suggesting inconsistent conclusions about the effectiveness of soft-shell padding in mitigating head impacts.

Study findings highlight importance in developing effective concussion prevention strategies in practice settings, given that the majority occur during practice.
Reflects on costs versus benefits regarding soft-shell padding deployment in football.

Findings are based on a small sample and may not be generalizable to all football populations.
Only one helmet type was study focus, restricting broader applicability.
Sampling omitted some impactful events due to video limitations and non-confirmed hits.

Preliminary findings suggest that soft-shell padding does not reduce head impact kinematics among chosen college football players.
Unfavorable findings provoke considerations on broader injury prevention methodologies in collision sports and call for cohesion in player behavior versus protective equipment efficacy.

Supporting material including the Consensus Head Acceleration Measurement Practices (CHAMP) checklist available at the provided site.

All authors contributed to the different stages of conceptualizing, conducting, and analyzing the study.
This study was partially funded by Football Research Inc.
Ethics approval by The University of North Carolina’s Institutional Review Board.
Informed consent obtained from participants.
There were no conflicts of interest reported by authors.