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Introduction The purpose of this study was to compare the rotational blunt impact performance of an anthropomorphic test device (ATD: male 50% Hybrid III head and neck) headform donning an Advanced Combat Helmet (ACH) between conditions in which the coefficient of static friction (μs) at the head-to-helmet pad interface varied. Materials and Methods Two ACHs (size large) were used in this study and friction was varied using polytetrafluoroethylene (PTFE), human hair, skullcap, and the native vinyl skin of the ATD. A condition in which hook and loop material adhered the headform to the liner system was also tested, resulting in a total of five conditions: PTFE, Human Hair, Skullcap, Vinyl, and Hook. Blunt impact tests with each helmet in each of the five conditions were conducted on a pneumatic linear impactor at 4.3 m/s. The ATD donning the ACH was impacted in seven locations (Crown, Front, Rear, Left Side, Right Side, Left Nape, and Right Nape). The peak resultant angular acceleration (PAA), velocity (PAV), and the Diffuse Axonal Multi-Axis, General Evaluation (DAMAGE) metric were compared between conditions. Results No pairwise differences were observed between conditions for PAA. A positive correlation was observed between mean μs and PAA at the Front (τ = 0.28; P = .044) and Rear (τ = 0.31; P = .024) impact locations. The Hook condition had a mean PAV value that was often less than the other conditions (P ≤ .024). A positive correlation was observed between mean μs and PAV at the Front (τ = 0.32; P = .019) and Right Side (τ = 0.57; P Conclusions The results of this study indicate that at some impact locations kinematic responses can vary as a function of the friction at the head-to-helmet pad interface. However, a reduction in the coupling of the head-helmet pad interface did not consistently reduce head angular kinematics or measures of brain strain across impact locations. Thus, for the ACH during collision-type impacts, impact location as opposed to μs seems to have a greater influence on head kinematics and rotational-based measures of brain strain.

In the effort to reduce concussions in American football, helmet manufacturers are seeking new technologies to reduce peak head impact kinematics. However, the efficacy of these new helmet technologies is unknown. Therefore, the purpose of this study was to evaluate the influence of an intermediary liner on the blunt impact kinematic performance of an American football helmet using a custom test similar to the NOCSAE (ND-081) and NFL linear impactor test methods. Twelve Schutt F7 football helmets with the Radian Diffusion System technology were evaluated under three conditions: with the system (hypothesized to function as a slip plane), without the system, and with a modified system using cloth to cover the hook and loop attachment that, by design, mechanically adheres the system to the comfort liner of the helmet. Helmets were impacted three times at 6 m/s (281 J) at six locations [side, rear boss non-centroidal, rear boss centroidal, rear, front boss, and a random location used for all helmets] using a pneumatic ram. While an effect was found for linear accelerations at the Rear, Rear Boss Center of Gravity, Rear Boss Non-Centroidal, and Random locations, no overall differences between liner conditions were observed for peak resultant linear (p = 0.310) and angular accelerations (p = 0.231), or peak resultant angular velocity (p = 0.127).

Compliant foams can be used to mitigate ground reaction forces. However, it is unknown how foam surfaces influence the modulation of leg muscle activity. Thus, the current study aimed to investigate how the neuromuscular system managed changes in expected loading due to various thickness of foam placed on the landing surface during a step down task. The surface electromyographic signal (sEMG) pre-activation duration and the root mean square (RMS) amplitude of tibialis anterior (TA), lateral gastrocnemius (LG), and vastus medialis (VM) of 10 active females were measured as they stepped-down with a single leg onto polyurethane foam slabs of varying thickness (0–50 mm). Pre-activation duration was not affected by the thickness of the foam padding. LG RMS amplitude was less in the foam conditions than the control (no– foam) condition, with the greatest reduction observed for the 50 mm foam condition. In some trials, the muscles remained active throughout the step-down task. In such instances, a sEMG onset time and thus a pre-activation duration could not be determined. All foam conditions significantly increased the odds of continuous muscle activity above that of the no-foam condition. The results indicate that foam surfaces may alter the modulation of muscle activity during step-down tasks.

Reproduction of anthropomorphic test device (ATD) head impact test methods is a critical element needed to develop guidance and technologies that reduce the risk for brain injury in sport. However, there does not appear to be a consensus for reporting ATD pose and impact location for industry and researchers to follow. Thus, the purpose of this article is to explore the various methods used to report impact location and ATD head pose for sport-related head impact testing and provide recommendations for standardizing these descriptions. A database search and exclusion process identified 137 articles that met the review criteria. Only 4 of the 137 articles provided a description similar to the method we propose to describe ATD pose and impact location. We thus propose a method to unambiguously convey the impact location and pose of the ATD based on the sequence, quantifiable design, and articulation of ATD mount joints. This reporting method has been used to a limited extent in the literature, but we assert that adoption of this method will help to standardize the reporting of ATD headform pose and impact location as well as aid in the replication of impact test protocols across laboratories.

The physical, cognitive, emotional, and financial costs associated with head injuries in sport can be great. Head injuries in sport can take different forms that range from obvious structural damage of the skull, mandible, and soft tissue to the subtler mild traumatic brain injury (mTBI). Regardless of injury type, most head injuries in sport typically result from biomechanical forces generated from either a head-to-object collision (e.g., playing surface or another player) or projectile-to-head collision (e.g., ball or stick). Over the modern era severe sport-related head injuries (e.g., skull fracture) have declined, but sport-related mTBIs—also referred to as sport-related concussions (SRCs)—have increased. This trend is highly problematic because of the serious nature of SRC’s symptoms, inherent sequelae (e.g., postconcussion syndrome and second impact syndrome), and potential for long-term cognitive decline (e.g., chronic traumatic encephalopathy). Since 2001 the International Symposium on Concussion in Sport has defined concussion as a “complex pathophysiological process affecting the brain, induced by traumatic biomechanical forces.” The definition continues to include several features that can be used to define the nature of concussion. The most recent definition of SRC developed at the 5th International Symposium on Concussion in Sport held in Berlin in 2016 defines SRC as “a traumatic brain injury induced by biomechanical forces.” The definition goes on to include several common features that could be used to define the nature of a concussion. These biomechanical forces can be generated via direct insult to the head or neck region or by forces encountered elsewhere on the body that are transmitted to the head. Unfortunately, uncertainty still exists for healthcare medical providers regarding the recognition of concussion, particularly for on-field providers and the best methods to prevent SRC. The primary objective of this chapter is to provide a broad overview of protective helmets in sport, their composition, and manufacturing processes.

Simple manipulation of force–time input is a potential strategy to increase the biofidelity of running footwear mechanical ageing. The purpose of this study was to compare a Dwell protocol, which i...

Mechanical stress exerted upon impact-modified polycarbonate (PC) and poly(ethylene terephthalate) (PET) blends has been reported to generate microscopic voids via rubber-toughener (RT) particle cavitation which can macroscopically manifest to visibly whiten the material. Previous work has revealed a whitening phenomenon in collegiate American football helmet outer shells after a single season and in helmet-grade plaques following linear impact testing. The purpose of this research was to quantify the effects of repetitive linear drop exposures on the (i) impact performance; (ii) physical and thermal properties; and (iii) surface and tensile mechanical properties of a stress-whitened American football helmet outer shell material. Statistically significant changes in plaque impact performance corresponded to substantial stress-whitening that penetrated up to 40–45% into the plaque thickness and elicited shifts in surface and tensile mechanical properties. Nanoscale microscopy revealed elongation of the PC/PET matrix and delamination at the RT-matrix interface. Thermal property analysis suggested the concomitant occurrence of RT cavitation and strain-induced PET crystallization. Overall, the research identified a battery of diagnostic tools to characterize material property changes of stress-whitening in rubber-toughened helmet outer shell materials.

The aim of this study was to obtain a fundamental understanding of how running shoe midsole foam thickness contributes to footwear degradation using the heel and forefoot regions of traditional (TS) and minimalist (MS) running shoes. We hypothesized that ethylene vinyl acetate (EVA) foam midsole material properties and footwear degradation performance under a biofidelic mechanical ageing protocol would differ as a function of shoe type and thickness. Attenuated total reflectance Fourier transform infrared spectra indicated that the foam chemical compositions were similar and confirmed that all midsoles were composed of EVA copolymer. Differences in density and cell size were detected between shoes and thicknesses. MS foam was uniformly high density (ρMS = 240 kg/m3), while TS foam consisted of two co-molded layers with forefoot density (ρTS-FF = 250 kg/m3) greater than heel (ρTS-H = 160 kg/m3). Relative density and cell size values were generally proportional and inversely proportional to density, respect...

American football helmets are subjected seasonally to a myriad of environmental conditions from expected use and storage and yet are reused without a relational understanding between service life degradation and changes in impact performance. Comprehensive investigations could link rates and degrees of material degradation to scientifically and clinically meaningful changes in helmet performance. Therefore, the purpose of this research was to preliminarily quantify the effects of accelerated weathering on (1) colorimetric, chemical, fluorescent, and thermal properties; (2) surface and bulk mechanical properties; and (3) impact performance of an American football helmet outer shell material. Helmet-grade plaques were exposed to 480 h of accelerated weathering. Surface-specific shifts ( p < 0.05) in colorimetric, chemical, fluorescent, thermal, and mechanical properties were observed at the plaque surface. Plaque-derived tensile specimens underwent monotonic tensile testing, and the photodegraded ∼1% of the Weathered plaque surface thickness led to 10%, 12%, and 9% increases ( p < 0.05) in Young’s modulus, yield stress, and ultimate tensile stress, respectively. Impact performance was analyzed with a protocol attempting to employ expected on-field impact conditions. Weathered and Non-weathered helmet surrogate systems managed impact energy progressively less effectively across five repetitive trials ( p < 0.05); yet the absence of significant Weathered differences demonstrated that the plaque–foam systems performed similarly. Results identified a battery of diagnostic tools to characterize the degradation of outer shell material exposed to accelerated weathering. Thus, the comprehensive approach herein may be used toward the evaluation of additional service life exposures, as well as examine on-field deterioration of full helmet outer shells.

Objective: To provide athletic trainers, health care professionals, and all those responsible for the care of athletes with clinical recommendations for preventing and managing sport-related dental and oral injuries.Background: Participation in competitive sports continues to grow at both the interscholastic and intercollegiate levels. Therefore, exposure to, and the incidence of athletic-related injury, including orofacial injury, will also likely increase. At the time of this writing, the leading governing agencies for interscholastic (National Federation of State High School Associations) and intercollegiate (National Collegiate Athletic Association) sports require only protective orofacial equipment (eg, mouthguards) for 5 and 4, respectively, of their sanctioned sports. Although orofacial injuries represent a small percentage of all sport-related injuries, the financial burden associated with these injuries (eg, tooth avulsion) can exceed $15 000 over an adult life. Therefore, effective management of sport-related dental injuries is critical to the long-term financial, physical, and emotional health of people who have experienced dental trauma.Recommendations: Based upon the current evidence regarding sport-related orofacial injury, we provide recommendations related to planning considerations, education, and mouthguard efficacy, material, fabrication, and care considerations. Additionally, suggested best practices for managing sport-related dental injury are also given for athletic trainers and other health care professionals.

The pursuit to abate sport-related concussion necessitates thorough evaluation of protective technologies and product claims. Therefore, the purpose of this investigation was to: (i) define the linear impulse and compression behavior of the Aware-Flow shock absorber (the primary energy managing component of Xenith X1 football helmet); (ii) characterize resultant force–time curves utilizing compressive loading behavior of foam materials; and (iii) verify and define published findings and product claims. Absorbers (N = 24) from three adult X1 football helmets were impacted at predefined velocities of 1.3, 2.3, 3.0, 4.0, and 4.7 m·s− 1. Linear impulsive forces were ideally managed up to 3.0 m·s− 1 (25.4 J). The foam-filled pad improved impact energy attenuation and increased velocity-specific durability. The leptokurtic region of the 4.0 and 4.7 m·s− 1 impulse curves substantiated a third phase, defined as densification, as demonstrated by the maximum compression height approaching 90%. The adoption of elast...

Context: Self-reported symptoms (SRS) scales comprise one aspect of a multifaceted assessment of sport-related concussion. Obtaining SRS assessments before a concussion occurs assists in determining when the injury is resolved. However, athletes may present with concussion-related symptoms at baseline. Thus, it is important to evaluate such reports to determine if the variables that are common to many athletic environments are influencing them. Objective: To evaluate the influence of a history of concussion, sex, acute fatigue, physical illness, and orthopaedic injury on baseline responses to 2 summative symptom scales; to investigate the psychometric properties of all responses; and to assess the factorial validity of responses to both scales in the absence of influential variables. Design: Cross-sectional study. Setting: Athletic training facilities of 6 National Collegiate Athletic Association institutions. Patients or Other Participants: The sample of 1065 was predominately male (n = 805) collegiate athletes with a mean age of 19.81 ± 1.53 years. Main Outcome Measure(s): Participants completed baseline measures for duration and severity of concussion-related SRS and a brief health questionnaire. Results: At baseline, respondents reporting a previous concussion had higher composite scores on both scales (P ≤ .01), but no sex differences were found for concussion-related symptoms. Acute fatigue, physical illness, and orthopaedic injury increased composite SRS scores on both duration and severity measures (P ≤ .01). Responses to both scales were stable and internally consistent. Confirmatory factor analysis provided strong evidence for the factorial validity of the responses of participants reporting no fatigue, physical illness, or orthopaedic injury on each instrument. Conclusions: A history of concussion, acute fatigue, physical illness, and orthopaedic injury increased baseline SRS scores. These conditions need to be thoroughly investigated and controlled by clinicians before baseline SRS measures are collected.

Objectives Several mechanisms have been purported to describe how mouthguards protect the orofacial complex against injury. As the properties needed for these mechanisms to be effective are temperature and frequency dependent, the specific aim of this study was to provide a comprehensive thermal characterization of commercial mouthguard materials. Methods Five commercially representative thermoplastic mouthguard materials (Essix™ Resin, Erkoflex™, Proform™-regular, Proform™-laminate, and Polyshok™) were tested. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) techniques were implemented to measure thermal transitions and mechanical properties. Measurements were conducted three times per sample. One-way ANOVA and one-sample t-tests were used to test for differences between commercial products on selected mean thermal property values. Results The DSC measurements indicated no differences between commercial materials for mean glass transition (p = 0.053), onset melt (p = 0.973), or peak melt (p = 0.436) temperatures. Likewise, DMA measurements revealed no differences between commercial materials for the mean glass transition (p = 0.093), storage modulus (p = 0.257), or loss modulus (p = 0.172) properties, respectively. The one-sample t-tests revealed that glass transition temperatures were different from intra-oral temperature (p Significance Commercialized mouthguard materials are sensitive to repetitive heating and cooling cycles, prolonged thermal treatment, and have glass transitions well below their end-use intra-oral temperature. As such, these materials are functioning as elastomers and not optimal mechanical damping materials. Dental clinicians, healthcare practitioners, or end-users should be aware that these materials are at best problematic with respect to this protective mechanism.

Contemporary mouthguard materials need to perform consistently over a wide range of possible temperatures (-20 to 40 degrees C). Therefore the specific aim of this study was to characterize commercialized mouthguard materials' properties and investigate the effect of temperature on these properties.Five commercially representative thermoplastic mouthguard materials (Essix Resin, Erkoflex, Proform-regular, Proform-laminate, and Polyshok) were tested. The durometer hardness, water absorption, tear strength, and impact attenuation of the mouthguard materials were measured according to ASTM D2240-05, D570-98 (2005), D624-00, and ASTM D6110-06f (modified) guidelines. Tests were conducted on five separate specimens at both room 23+/-2 degrees C and intra-oral 37+/-2 degrees C temperatures. Independent t-tests (alpha=0.05) were used to test for differences between room and intra-oral temperatures.Material hardness decreased (p0.05) from room to intra-oral temperatures for all mouthguard materials. Water absorption increased (p0.05) from room to intra-oral temperatures for all mouthguard materials. Tear strength decreased (p0.05) from room to intra-oral temperatures for all mouthguard materials. Impact attenuation between room and intra-oral temperatures was different (p0.05) for the Erkoflex, Proform-laminate, and Polyshok material respectfully. However, there was no difference between temperatures for the Essix Resin (p=.058) or Proform-regular (p=.275) materials.Temperature measureably affects the physical and mechanical properties of mouthguard materials. It is particularly noteworthy that none of the commercialized products met current ANSI and SAI standards for impact attenuation.

Model ternary thiol−ene/acrylate photopolymerization involving acrylate homopolymerization and copolymerization of thiol−ene and thiol−acrylate monomers were monitored by real-time FTIR. In all ternary mixtures, including those prepared with different acrylate concentrations, acrylate conversion was 100%. However, thiol−ene conversions were found to be controlled by their initial concentrations. The influence of acrylate monomer chemical structure on the thermophysical properties of ternary thiol−ene/acrylate systems was studied with DMA, DSC, and the absorbance of a nondestructive impact energy. The addition of acrylate to the thiol−ene system increased the rubbery modulus while the tan δmax shifted to higher temperatures. Densely cross-linked, heterogeneous matrix formation was observed with the broadening of tan δ peaks at high acrylate concentrations. The high impact absorption of these ternary thermoset photopolymers was correlated with the dynamic mechanical damping ability of the networks. Acrylate...

Participation in contact sports across all levels carries a risk of sustaining a head injury through an impact event. As part of the protective “garment,” sports headgear serves to mitigate the deleterious effects of these head collisions. However, performance requirements for sports headgear vary due to a myriad of expected service-life conditions. As such, polymeric materials must provide the essential properties for processing, construction, and management of the cumulative degradative exposures of helmet material storage and use. Sectors of the sport headgear industry have implemented reconditioning and recertification processes for helmets due to deterioration in an effort to maintain initial performance standards. Analytical polymer science techniques can assist sport engineers to monitor changes in functional properties throughout the helmet life span as well as aid in product development processes. Additional efforts to mitigate sport-related head trauma include development of novel pneumatic liner systems, composite outer shells, and aftermarket additive helmet technologies.

Background: The long term effects of self reported concussion on neurocognitive functioning have been found to be variable. Objectives: To evaluate cognitive performance on the Headminder concussion resolution index (CRI) and ImPACT assessment tests of subjects with and without a history of self reported concussion. Methods: A retrospective analysis was completed on 235 Headminder CRI baseline assessments and 264 ImPACT baseline assessments. Participants were divided into four groups on the basis of reported number of concussions (zero, one, two, or three). Multivariate analysis of variance was used to evaluate differences between the concussion history groups on the two computer based concussion assessment programs. Results: Multivariate analysis of variance indicated no significant difference between those with and without a history of concussion on the CRI (Λ = 0.963, F (15, 627.05) = 0.57, p = 0.898). It also revealed no significant differences between groups on the ImPACT test (Λ = 0.951, F (12, 672.31) = 1.07, p = 0.381). Conclusions: The results suggest that either long term cognitive decrements may not be associated with a history of concussion or the decrements may be subtle and undetectable by these computer programs.

This study evaluated the factorial validity of a self-report measure of concussion-related symptom severity among a large sample of male, high-school athletes.Participants (N = 1089) were nonconcussed, male, high-school football players. All participants completed a single baseline self-report measure of concussion-related symptom severity, namely the graded symptom checklist (GSC). We tested the factorial validity of the measure with confirmatory factor analysis using LISREL 8.50.The analysis indicated that a theoretically derived, three-factor model provided a good, but not excellent, fit for the 16-item GSC. Excellent model-data fit was demonstrated for the three-factor model for a 9-item version of the GSC. In both instances, the three factors were best described by a single second-order factor, namely concussion symptomatology.This study provides additional evidence for the factorial validity of a summative self-reported measure of concussion-related symptoms. The factor structure represents a cohesive group of nine symptoms that can be explained by three underlying latent variables, namely somatic symptoms, neurobehavioral symptoms, and "cognitive" symptoms, subsumed under a single higher-order factor, namely concussion symptoms.

The goal of this study is to compare the thermal and mechanical properties of a commercial mouthguard material with a novel class of thermoset polymers based on thiolene “click” chemistry. Ternary thiolene systems modified with urethane or acrylate [urethane-modified thiolene network (UMTEN) and acrylate-modified thiolene network (AMTEN), respectively] were synthesized and their properties compared with commercially available Polyshok™. Durometer hardness (ASTM D2240-05), water absorption [ASTM D570-98 (2005)], tear strength (ASTM D624-00), and impact attenuation [ASTM D6110-06f (modified)] were measured for physical property comparison. Differential scanning calorimetry and dynamic mechanical analysis were used as a means to compare thermal properties. One-way analysis of variance and independent t tests were used to test for differences between Polyshok™, AMTEN and UMTEN samples. It was found that the novel thiolene networks exhibit higher impact attenuation at intraoral temperature compared with Polyshok™, although Polyshok™ demonstrates lower water absorption and hardness, as well as higher tear strength. With further modification, this family of thiolene materials may provide a platform for developing next-generation mouthguard materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40402.

Context: Didactic proficiency does not ensure clinical aptitude. Quality athletic health care requires clinical knowledge and affective traits. Objective: To develop a grounded theory explaining the constructs of a quality certified athletic trainer (AT). Design: Delphi study. Setting: Interviews in conference rooms or business offices and by telephone. Patients or Other Participants: Thirteen ATs (men = 8, women = 5) stratified across the largest employment settings (high school, college, clinical) in the 4 largest districts of the National Athletic Trainers' Association (2, 3, 4, 9). Data Collection and Analysis: Open-ended interview questions were audio recorded, transcribed, and reviewed before condensing. Two member checks ensured trustworthiness. Open coding reduced text to descriptive adjectives. Results: We grouped adjectives into 5 constructs (care, communication, commitment, integrity, knowledge) and grouped these constructs into 2 higher-order constructs (affective traits, effective traits). Conclusions: According to participants, ATs who demonstrate the ability to care, show commitment and integrity, value professional knowledge, and communicate effectively with others can be identified as quality ATs. These abilities facilitate the creation of positive relationships. These relationships allow the quality AT to interact with patients and other health care professionals on a knowledgeable basis that ultimately improves health care delivery. Our resulting theory supported the examination of characteristics not traditionally assessed in an athletic training education program. If researchers can show that these characteristics develop ATs into quality ATs (eg, those who work better with others, relate meaningfully with patients, and improve the standard of health care), they must be cultivated in the educational setting.

Participation in sports across all age-groups plays an important role in the overall health of nations with cohort studies suggesting a 20%–40% reduction in all-cause mortality among active participants compared to nonparticipants. Further, global participation in sport is at an all-time high as global inactivity rates have been shown to be as low as 17% in Southeast Asia to 43% in the Americas. Around the world, participation increases have served to elevate sports such as soccer, basketball, gymnastics, and running which represent the most popular global sporting disciplines. It is logical to infer that an increase in athlete participation creates a concomitant increase in athlete exposure to risk of injury (including orofacial injuries). Potential orofacial maladies include fractures to bones of the face and jaw. Likewise, teeth can be chipped, fractured, dislocated, concussed, and/or avulsed. The direct mechanisms that cause these injuries may also be associated with brain concussion or sports-related mild traumatic brain injury. It has been suggested, although not scientifically proven, that impact forces to the jaw may be transmitted to the base of the brain via the mandibular condyles resulting in concussive insult. Regardless of mechanism, dental trauma is a serious and global public health problem that mostly affects the youth and participants in organized sport. In addition, dental trauma carries with it both significant short-term and long-term injury sequelae (e.g., root resorption). In the United States, estimates of dental rehabilitation costs because of sports-related orofacial injuries have been estimated at US$15,000 per tooth over the span of a lifetime for athletes who lose a tooth. These types of injuries carry with them physical, emotional, and financial costs.

With increasing knowledge and research about concussion, there have been few objective studies that have used neuropsychological domain scores and postural stability to assess concussion.To evaluate the recovery curve of athletes who incur sport-related concussion from repeated serial testing of neuropsychological and posturography testing.A prospective epidemiological model was used for the course of the study.Division I intercollegiate athletics.Athletes participating in football, soccer, basketball, softball, and cheerleading.Neuropsychological scores and posturography measures were obtained preseason and serially at day 1, day 2, day 3, and day 10 postconcussion. Control participants were tested at the same intervals. Neuropsychological scores were converted to standards score and then into domains of attention, learning, speed of information processing, concentration, memory, and verbal fluency. Analysis of covariance with the baseline test as the covariate was used to analyze the data with univariate post hoc tests performed.Significant group differences were found for self reported symptoms (P = 0.001), speed of information processing (P = 0.005), mean stability (P = 0.002), and vestibular function (P = 0.003) between injured and control participants. A group, by day, planned comparison found that speed of information processing and composite balance measures demonstrated significant differences through day 10 postinjury, while symptoms and the vestibular ratio remained significant only through day 3.The concussion recovery curve demonstrated short-term neuropsychological and posturography deficits following injury. A comprehensive approach to concussion management should be used to assess the injury and make return-to-play decisions.

Expected service life of a football helmet involves a myriad of impact events and environmental conditions that lead to a variety of degradative processes. This study investigated the effect of accelerated outdoor weathering on the impact performance of a helmet outer shell material. Helmet-grade material plaques of 1/8“thickness (N=12) were assigned into two groups: weathered (n=6) and non-weathered (n=6). Weathered plaques were exposed to accelerated outdoor weathering following ASTM G-154 for 480hours and characterized with infrared spectroscopy (ATR-IR). Impact tests were performed with an instrumented drop tower at 5.5 m/sec with a 5.64kg drop weight upon plaque-foam systems using 1.5” VN600 foam across five trials. Impact results were analyzed via a 2 (condition: weathering, non-weathering) X 5 (trials: 1-5) mixed model repeated measures ANOVA. Exposed area of weathered plaques showed visible discoloration along with significant alkyl functional group consumption noted at 3000-2800cm-1 (t=14.779, p

Existing attempts to evaluate footwear via cyclic compression fail to sufficiently represent biofidelic force-time curves or provide the underlying mechanism of EVA foam fatigue. A uniaxial biofidelic waveform was compared to a sine wave of the same frequency to examine differences in (1) net displacement, (2) absorbed energy, and (3) peak force from ASTM F1614. A non-destructive molecular-level technique (ATR-FTIR) recorded differences in hydroxyl, ester, and unsaturated moieties due to EVA degradation. It was concluded that (1) biofidelic waveforms may better simulate human running, (2) material degradation is discernible, and (3) inferences regarding polymeric degradation and macroscopic performance require further investigation.

The pursuit to maintain the initial performance standard of American football helmets has prompted the implementation of a certified reconditioning and recertification process. Thus, the purpose of this study is to: (i) develop a method to replicate solvent exposure during the reconditioning painting process, (ii) compare selected solvent exposure intensities, and (iii) quantify shifts in material and impact properties of an American football helmet outer shell material. Spraying yielded uniformly exposed samples and was substantiated for investigation of solvent effects. Exposures of n-Butyl acetate to the helmet-grade material surface led to shifts in colorimetric, dimensional, thermal, and tensile properties. Impact performance of helmet surrogate systems performed equivalently. Overall, results substantiated spraying as representative of the reconditioning process and demonstrated shifts in material properties via solvent-induced degradation of helmet-grade outer shell materials.