Influence of Friction at the Head-Helmet Interface on Advanced Combat Helmet (ACH) Blunt Impact Kinematic Performance.

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 < .001) locations. The Hook condition tended to have the lowest DAMAGE value compared to the other conditions (P ≤ .032). A positive correlation was observed between the mean µs and DAMAGE at the Rear (τ = 0.60; P < .001) location. A negative correlation was observed at the Left Side (τ = -0.28; P = .040), Right Side (τ = -0.58; P < .001) and Left Nape (τ = -0.56; P < .001) locations. 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.

Influence of foam thickness on the control of EMG activity during a step-down task in females.

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.

Describing headform pose and impact location for blunt impact testing.

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.

Laboratory Performance Evaluation of Pristine and Used Headgear for Girls' Lacrosse.

Girls' lacrosse participation and head injury rates have increased within the past decade. In response, optional headgear was implemented following the recently developed ASTM International (ASTM) lacrosse headgear performance standards. It remains unknown how lacrosse headgear responds to blunt impacts after use. Our purpose was to compare the peak linear acceleration (PLA) between girls' lacrosse headgear conditions (pristine and used) during blunt impacts. Pristine headgear (n=10) were tested in their original condition and used headgear (n=10) were worn for an entire competitive season. A Cadex Monorail Impactor impacted all headgear following ASTM standards (F1446-15b, F2220-15, and F3137-15) in the required testing locations. A 2 x 7 repeated measures ANOVA compared PLA among headgear conditions and impact locations with a simple effects analysis planned comparison. There was no difference between headgear conditions for PLA (Pristine: 47.12 ± 13.92g; Used: 46.62 ± 14.84g; F = 2.11, p > 0.05). A main effect for impact location (F = 983.52, p < 0.01), and an interaction effect of condition and impact location (F = 12.79, p < 0.01) were observed. All headgear, regardless of condition, met the ASTM performance standard. This suggests that headgear performance may not degrade subsequent to a single season of high school girl's lacrosse.

National Athletic Trainers' Association Position Statement: Preventing and Managing Sport-Related Dental and Oral Injuries.

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.

Impact properties of thiol-ene networks.

In this study, a series of thiol-ene networks having glass transition temperatures ranging from -30 to 60 °C were synthesized utilizing several multifunctional thiols and two trifunctional alkenes. Thermomechanical properties were determined using dynamic mechanical analysis, and impact properties were determined using pendulum impact and drop impact testing protocols. The impact behavior was found to directly correlate to the glass transition temperature, except when the temperature at which the impact event occurs overlaps with the range of temperatures corresponding to the viscoelastic dissipation regime of the polymer. Additionally, we discuss insight into the spatial limitations of energy dissipation for thiol-ene network polymers and establish a platform for predictability in similar systems.

Characterizations of a quality certified athletic trainer.

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.

Investigation of baseline self-report concussion symptom scores.

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

Characterization of mouthguard materials: thermal properties of commercialized products.

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<0.005) for all materials. 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.

Antecedents of ethical decision-making: intercollegiate sporting environments as clinical education and practice settings.

Unique among allied health care professions, athletic training is predominately practiced amid competitive intercollegiate sports. Competitive sporting environments have been suggested to adversely impact morality, ethical decision-making (EDM), and behavior. The purposes of this study were to (1) investigate the effect of institutional National Collegiate Athletic Association (NCAA) participation level on preferred ethical ideologies and EDM, (2) determine the relationship between professional status (athletic training student [ATS] or certified athletic trainer [ATC]) and ethical ideology preferences and EDM, and (3) examine whether preferred ethical ideology is related to differences in EDM. A nationally representative sample of 610 ATSs and ATCs from 30 athletic training education programs, stratified by NCAA division level, participated in the study. All participants completed a demographic survey, the Ethics Position Questionnaire, and the Dilemmas in Athletic Training Questionnaire. No significant relationships were noted between NCAA participation level and respondents' ethical ideology preferences. However, ATSs and ATCs demonstrated significant preferences for specific ethical ideologies, with students adopting the subjectivist ideology more than expected and the exceptionist ideology less than expected and ATCs adopting the exceptionist ideology more than expected and the situationist ideology less than expected. In contrast to some previous research, our results suggest that competitive sporting environments do not affect ATSs' and ATCs' ethical ideology and EDM abilities at the collegiate level. These findings serve as a baseline for future research examining the ethical ideologies and ethical decision-making levels of athletic training practitioners and other allied health professionals across clinical settings.

Characterization of mouthguard materials: physical and mechanical properties of commercialized products.

OBJECTIVES: 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. METHODS: 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. RESULTS: Material hardness decreased (p<0.05) from room to intra-oral temperatures for all mouthguard materials. Water absorption increased (p<0.05) from room to intra-oral temperatures for all mouthguard materials. Tear strength decreased (p<0.05) from room to intra-oral temperatures for all mouthguard materials. Impact attenuation between room and intra-oral temperatures was different (p<0.05) 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. SIGNIFICANCE: 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.

Individual moral philosophies and ethical decision making of undergraduate athletic training students and educators.

CONTEXT: Ethics research in athletic training is lacking. Teaching students technical skills is important, but teaching them how to reason and to behave in a manner that befits responsible health care professionals is equally important. OBJECTIVE: To expand ethics research in athletic training by (1) describing undergraduate athletic training students' and educators' individual moral philosophies and ethical decision-making abilities and (2) investigating the effects of sex and level of education on mean composite individual moral philosophies and ethical decision-making scores. DESIGN: Stratified, multistage, cluster-sample correlational study. SETTING: Mailed survey instruments were distributed in classroom settings at 30 institutions having Commission on Accreditation of Allied Health Education Programs (CAAHEP)-accredited athletic training programs. PATIENTS OR OTHER PARTICIPANTS: Undergraduate students and educators (n = 598: 373 women, 225 men; mean age = 23.5 +/- 6.3 years) from 25 CAAHEP-accredited athletic training programs. MAIN OUTCOME MEASURE(S): We used the Ethics Position Questionnaire and the Dilemmas in Athletic Training Questionnaire to compute participants' mean composite individual moral philosophies (idealism and relativism) and ethical decision-making scores, respectively. Three separate 2 (sex: male, female) x 3 (education level: underclass, upper class, educator) between-subjects factorial analyses of variance using idealism, relativism, and ethical decision-making scores as dependent measures were performed. RESULTS: Respondents reported higher idealism scores (37.57 +/- 4.91) than relativism scores (31.70 +/- 4.80) (response rate = 83%). The mean ethical decision-making score for all respondents was 80.76 +/- 7.88. No significant interactions were revealed. The main effect for sex illustrated that men reported significantly higher relativism scores ( P = .0014, eta (2) = .015) than did women. The main effect for education level revealed significant differences between students' and educators' idealism ( P = .0190, eta (2) = .013), relativism ( P < .001, eta (2) = .050), and ethical decision-making scores ( P < .001, eta (2) = .027). Tukey honestly significant difference post hoc analysis indicated that educators possessed lower idealism scores (36.90 +/- 5.70) and relativism scores (29.92 +/- 4.86) and higher ethical decision-making scores (82.98 +/- 7.62) than did students. CONCLUSIONS: Our findings do not support changes in athletic training ethics education practices to address sex-specific needs. However, when opportunities occur for students to reason using different ethical perspectives, educators should be aware of their students' and their own moral philosophies in order to optimally facilitate professional growth.

Stylistic learning differences between undergraduate athletic training students and educators: Gregorc mind styles.

CONTEXT: Learning theory and pedagogic research are unfamiliar to many educators trained in the sciences. Athletic training educators must learn to appreciate the theoretic and practical value of pedagogic research, including learning styles. OBJECTIVE: To extend the learning styles research in athletic training by introducing the Mind Styles model and Gregorc Style Delineator instrument to investigate students' and program directors' baseline style preferences and to study the effects of sex, education level, and academic role on mean composite Gregorc Style Delineator scores. DESIGN: Correlational research design. SETTING: Instruments were mailed to program directors and administered in classroom settings. PATIENTS OR OTHER PARTICIPANTS: Ten of 10 athletic training programs accredited by the Commission on Accreditation of Allied Health Education Programs formed sample 1, with 200 undergraduate athletic training students (68 men, 132 women, age = 20.12 +/- 2.02 years). A total of 43 program directors (22 men, 21 women, age = 40.05 +/- 9.30 years) created sample 2. MAIN OUTCOME MEASURE(S): We used the Gregorc Style Delineator to measure participants' perceptual and ordering abilities, combining them in a quaternary design to create mean composite scores for the Concrete Sequential (CS), Abstract Sequential (AS), Abstract Random (AR), and Concrete Random (CR) Mind Styles subscales. We also noted each subject's sex, education level, and academic role. RESULTS: We obtained a response rate of 100% of undergraduates and 43% of program directors. The CS style was preferred by 44.5% (n = 89) of students and 58.1% (n = 25) of program directors. Program directors preferred the CS style more (P < .001) and the AS and AR styles less (P < .001) than predicted by chi(2) testing. Students preferred the CS style more (P < .001) and the AS style less (P < .001) than expected also. Men students preferred the AS style more (P < .01) and the AR style less (P < .01) than women students. Students by chi2 testing were also less likely to prefer the CS style (P < .01) and more likely to prefer the AR style (P < .001) than program directors. No significant main effect was noted for education level (P = .310) or the interaction (P = .108). CONCLUSIONS: Our findings add 2 unique elements to the athletic training literature by extending the investigation of styles to an original model (Mind Styles) and the effect of academic role on style. Program directors should strongly consider sex and academic role style differences when designing and implementing pedagogic methods.

Preferred teaching and testing methods of athletic training students and program directors and the relationship to styles.

OBJECTIVE: The purpose of this study was (1) to investigate differences between athletic training students' and program directors' preferences for teaching and testing methods and (2) to investigate the relationship between style and preferred teaching and testing methods using the Gregorc Style Delineator (GSD) and the Preferred Teaching and Testing Method Inventory (PTTMI). PARTICIPANTS: We cluster sampled 200 undergraduate students (100% return; 68 men, 132 women; mean age, 20.12 +/- 2.02 yrs) and simple random sampled 100 program directors (43% return; 22 men, 21 women; mean age, 40.05 +/- 9.30 yrs) from Commission on Accreditation of Allied Health Education Programs-accredited athletic training education programs. DESIGN AND MEASUREMENT: We used a correlational research design to compare the preferred teaching and testing methods of undergraduate students and program directors. All subjects completed a demographic survey, the GSD, and the PTTMI. Our analyses included two separate 2 (role: student and program director) x 8 (method: teaching or testing techniques) and two separate 4 (style: concrete sequential, abstract sequential, abstract random, concrete random) x 8 (method: teaching and testing techniques) mixed-model analyses of variance. RESULTS: We found that athletic training students and program directors had significantly different preferences for teaching (p < 0.01) and testing (p < 0.01) methods, respectively. No significant relationships were revealed between athletic training students' and program directors' Mind Style typologies and their preferences for teaching or testing method. CONCLUSIONS: We recommend that athletic training and allied health educators consider implementing pedagogy that accentuates students' styles and consider self and students' preferences for preferred teaching and testing methods as time and topic permit.

Efficacy of Rugby Headgear in Attenuating Repetitive Linear Impact Forces.

OBJECTIVE: To determine the effectiveness of rugby headgear and the effect of impact site and headgear type on attenuating repetitive linear impact forces. DESIGN AND SETTING: We obtained 10 headgear of 2 different types (n = 20) from 2 popular manufacturers: type I was Honeycomb headgear and type II was Vanguard headgear. Both headgear types were approved by the International Rugby Board. Headgear were tested according to National Operating Committee on Standards for Athletic Equipment protocols with one modification. The headgear were dropped from a height of 30 cm according to the International Rugby Board standards. Headgear were tested at a National Athletic Equipment Reconditioners Association facility. MEASUREMENTS: We recorded peak acceleration of gravity (g) and Gadd Severity Index readings for each impact. The design of the study was 4 one-way, within-subjects, repeated-measures analyses of variance with alpha =.05. Descriptive statistics were calculated for all categoric variables. RESULTS: Peak g and Gadd Severity Index increased with repetitive impacts, resulting in a headgear's decreased ability to attenuate linear impact forces. Attenuation differed significantly between headgear type I and type II at both impact sites and between the parietal-lateral and occipital impact sites for both headgear types. CONCLUSIONS: The headgear initially attenuated impact forces from a drop height of 30 cm. However, over 10 drops, both headgear decreased in their ability to attenuate repetitive linear impact forces. Decreased attenuation in the occipital region as well as significant differences in attenuation abilities between headgear types support the need for further investigation to examine the efficacy of rugby headgear.