RESUMEN
The relationship between head impact and subsequent brain injury for American football players is not well-defined, especially for youth. The objective of this study is to quantify and assess Head Impact Exposure (HIE) metrics among youth and collegiate football players. This multi-season study enrolled 639 unique athletes (354 collegiate; 285 youth, ages 9-14), recording 476,209 head impacts (367,337 collegiate; 108,872 youth) over 971 sessions (480 collegiate; 491 youth). Youth players experienced 43 and 65% fewer impacts per competition and practice, respectively, and lower impact magnitudes compared to collegiate players (95th percentile peak linear acceleration (PLA, g) competition: 45.6 vs 61.9; 95th percentile PLA practice: 42.6 vs 58.8; 95th percentile peak rotational acceleration (PRA, rad·s-2) competition: 2262 vs 4422; 95th percentile PRA practice: 2081 vs 4052; 95th percentile HITsp competition: 25.4 vs 32.8; 95th percentile HITsp practice: 23.9 vs 30.2). Impacts during competition were more frequent and of greater magnitude than during practice at both levels. Quantified comparisons of head impact frequency and magnitude between youth and collegiate athletes reveal HIE differences as a function of age, and expanded insight better informs the development of age-appropriate guidelines for helmet design, prevention measures, standardized testing, brain injury diagnosis, and recovery management.
Asunto(s)
Conmoción Encefálica , Lesiones Encefálicas , Fútbol Americano , Adolescente , Humanos , Niño , Fútbol Americano/lesiones , Dispositivos de Protección de la Cabeza , Aceleración , Cabeza , Poliésteres , Fenómenos BiomecánicosRESUMEN
OBJECTIVES: The Ice Hockey Summit III provided updated scientific evidence on concussions in hockey to inform these 5 objectives: (1) describe sport related concussion (SRC) epidemiology; (2) classify prevention strategies; (3) define objective, diagnostic tests; (4) identify treatment; and (5) integrate science and clinical care into prioritized action plans and policy. METHODS: Our action plan evolved from 40 scientific presentations. The 155 attendees (physicians, athletic trainers, physical therapists, nurses, neuropsychologists, scientists, engineers, coaches, and officials) voted to prioritize these action items in the final Summit session. RESULTS: To (1) establish a national and international hockey database for SRCs at all levels; (2) eliminate body checking in Bantam youth hockey games; (3) expand a behavior modification program (Fair Play) to all youth hockey levels; (4) enforce game ejection penalties for fighting in Junior A and professional hockey leagues; (5) establish objective tests to diagnose concussion at point of care; and (6) mandate baseline testing to improve concussion diagnosis for all age groups. CONCLUSIONS: Expedient implementation of the Summit III prioritized action items is necessary to reduce the risk, severity, and consequences of concussion in the sport of ice hockey.
Asunto(s)
Traumatismos en Atletas , Conmoción Encefálica , Hockey , Traumatismos en Atletas/diagnóstico , Traumatismos en Atletas/epidemiología , Traumatismos en Atletas/prevención & control , Conmoción Encefálica/diagnóstico , Conmoción Encefálica/epidemiología , Conmoción Encefálica/prevención & control , Congresos como Asunto , Hockey/lesiones , Humanos , IncidenciaRESUMEN
The objective of this study was to determine the psychometrics (reliability, validity) of the original Standardized Assessment of Concussion (SAC) in a youth sample (ages 11 to 13). Demographic factors of race, level of vocabulary knowledge, mother's level of education were also considered. Over 150 youth football athletes completed the SAC and a brief battery of NIH Toolbox cognitive tests as part of a larger study on biomechanical factors in youth sport concussion. This was a within-subjects design (pre-season, post-season assessments), and correlational analysis of convergent and discriminant validity. Between groups analysis based on demographic differences was also employed. The pre-season SAC scores were not different by age; however, SAC scores were statistically different by race: t(155) = 3.162, p = .002, d = .519. Maternal level of education and participant vocabulary scores were related to racial group membership. Convergent and discriminant validity were established compared to NIH Toolbox tests of memory and speed. Pre-post-season tests for 108 participants established marginally acceptable test-retest reliability (ICC = .692). These data support the use of the original SAC in youth football although clinicians must be aware of racial differences in scores.
Asunto(s)
Conmoción Encefálica , Fútbol Americano , Adolescente , Conmoción Encefálica/diagnóstico , Niño , Demografía , Humanos , Psicometría , Reproducibilidad de los ResultadosRESUMEN
OBJECTIVES: Head impact exposure (HIE) in youth football is a public health concern. The objective of this study was to determine if one season of HIE in youth football was related to cognitive changes. METHOD: Over 200 participants (ages 9-13) wore instrumented helmets for practices and games to measure the amount of HIE sustained over one season. Pre- and post-season neuropsychological tests were completed. Test score changes were calculated adjusting for practice effects and regression to the mean and used as the dependent variables. Regression models were calculated with HIE variables predicting neuropsychological test score changes. RESULTS: For the full sample, a small effect was found with season average rotational values predicting changes in list-learning such that HIE was related to negative score change: standardized beta (ß) = -.147, t(205) = -2.12, and p = .035. When analyzed by age clusters (9-10, 11-13) and adding participant weight to models, the R2 values increased. Splitting groups by weight (median split), found heavier members of the 9-10 cohort with significantly greater change than lighter members. Additionaly, significantly more participants had clinically meaningful negative changes: X2 = 10.343, p = .001. CONCLUSION: These findings suggest that in the 9-10 age cluster, the average seasonal level of HIE had inverse, negative relationships with cognitive change over one season that was not found in the older group. The mediation effects of age and weight have not been explored previously and appear to contribute to the effects of HIE on cognition in youth football players.
Asunto(s)
Conmoción Encefálica , Fútbol Americano , Fútbol , Adolescente , Conmoción Encefálica/epidemiología , Conmoción Encefálica/etiología , Niño , Dispositivos de Protección de la Cabeza , Humanos , Pruebas Neuropsicológicas , Estaciones del AñoRESUMEN
The long-term neurologic consequences of exposure to repetitive head impacts (RHI) are not well understood. This study used magnetic resonance spectroscopy (MRS) to examine later-life neurochemistry and its association with RHI and clinical function in former National Football League (NFL) players. The sample included 77 symptomatic former NFL players and 23 asymptomatic individuals without a head trauma history. Participants completed cognitive, behavior, and mood measures. N-acetyl aspartate, glutamate/glutamine, choline, myo-inositol, creatine, and glutathione were measured in the posterior (PCG) and anterior (ACG) cingulate gyrus, and parietal white matter (PWM). A cumulative head impact index (CHII) estimated RHI. In former NFL players, a higher CHII correlated with lower PWM creatine (r = -0.23, p = 0.02). Multivariate mixed-effect models examined neurochemical differences between the former NFL players and asymptomatic individuals without a history of head trauma. PWM N-acetyl aspartate was lower among the former NFL players (mean diff. = 1.02, p = 0.03). Between-group analyses are preliminary as groups were recruited based on symptomatic status. The ACG was the only region associated with clinical function, including positive correlations between glutamate (r = 0.32, p = 0.004), glutathione (r = 0.29, p = 0.02), and myo-inositol (r = 0.26, p = 0.01) with behavioral/mood symptoms. Other positive correlations between ACG neurochemistry and clinical function emerged (i.e., behavioral/mood symptoms, cognition), but the positive directionality was unexpected. All analyses controlled for age, body mass index, and education (for analyses examining clinical function). In this sample of symptomatic former NFL players, there was a direct effect between RHI and reduced cellular energy metabolism (i.e., lower creatine). MRS neurochemicals associated with neuroinflammation also correlated with behavioral/mood symptoms.
Asunto(s)
Fútbol Americano , Fútbol , Sustancia Blanca , Humanos , Imagen por Resonancia Magnética , Espectroscopía de Resonancia MagnéticaRESUMEN
Physical differences between youth and adults, which include incomplete myelination, limited neck muscle development, and a higher head-body ratio in the youth population, likely contribute towards the increased susceptibility of youth to concussion. Previous research efforts have considered the biomechanics of concussion for adult populations, but these known age-related differences highlight the necessity of quantifying the risk of concussion for a youth population. This study adapted the previously developed Generalized Acceleration Model for Brian Injury Threshold (GAMBIT) that combines linear and rotational head acceleration to model the risk of concussion for a youth population with the Generalized Acceleration Model for Concussion in Youth (GAM-CY). Survival analysis was used in conjunction with head impact data collected during participation in youth football to model risk between individuals who sustained medically-diagnosed concussions (n = 15). Receiver operator characteristic curves were generated for peak linear acceleration, peak rotational acceleration, and GAM-CY, all of which were observed to be better injury predictors than random guessing. GAM-CY was associated with an area under the curve of 0.89 (95% confidence interval: 0.82-0.95) when all head impacts experienced by the concussed players were considered. Concussion tolerance was observed to be lower for youth athletes, with average peak linear head acceleration of 62.4 ± 29.7 g compared to 102.5 ± 32.7 g for adults and average peak rotational head acceleration of 2609 ± 1591 rad/s2 compared to 4412 ± 2326 rad/s2. These data provide further evidence of age-related differences in concussion tolerance and may be used for the development of youth-specific protective designs.
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Aceleración , Conmoción Encefálica/fisiopatología , Cabeza/fisiología , Modelos Teóricos , Rotación , Acelerometría , Adolescente , Niño , Fútbol Americano/fisiología , Humanos , RiesgoRESUMEN
BACKGROUND: Concern for head injuries is widespread and has been reported by the media to be the number one cause of decreased participation in football among the American youth population. Identifying player mechanisms associated with intentional, or purposeful, head impacts should provide critical data for rule modifications, educational programs, and equipment design. PURPOSE: To investigate the frequency of intentional and unintentional head impacts and to examine the player mechanisms associated with intentional high-magnitude head impacts by comparing the impact mechanism distributions among session type, player position, and ball possession. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Head impact sensors and video footage of 68 players were used to analyze and classify 1319 high-magnitude impacts recorded over 1 season of youth football. RESULTS: In total, 80% of the high-magnitude head impacts were classified as being caused by intentional use of the head. Head-to-head impact was the primary impact mechanism (n = 868; 82.7%) within the 1050 intentional high-magnitude impacts, with classifiable mechanisms, followed by head-to-body (n = 139; 13.2%), head-to-ground (n = 34; 3.2%), and head-to-equipment (n = 9; 0.9%). Head-to-head impacts also accounted for a greater proportion of impacts during practices (n = 625; 88.9%) than games, for linemen (n = 585; 90.3%) than perimeters and backs, and for ball carriers (n = 72; 79.1%) than tacklers. CONCLUSION: Overall, the majority of high-magnitude head impacts were intentional and resulted from head-to-head contact. The proportion of head-to-head contact was significantly higher for practices than games, linemen than backs and perimeter players, and ball carriers than tacklers.
Asunto(s)
Aceleración , Traumatismos Craneocerebrales/epidemiología , Fútbol Americano/lesiones , Adolescente , Conmoción Encefálica/epidemiología , Estudios Transversales , Diseño de Equipo , Movimientos de la Cabeza , Dispositivos de Protección de la Cabeza , Humanos , Masculino , Medición de Riesgo , Estados UnidosRESUMEN
The Ice Hockey Summit III provided updated scientific evidence on concussions in hockey to inform these five objectives: 1) describe sport-related concussion (SRC) epidemiology, 2) classify prevention strategies, 3) define objective, diagnostic tests, 4) identify treatment, and 5) integrate science and clinical care into prioritized action plans and policy. Our action plan evolved from 40 scientific presentations. The 155 attendees (physicians, athletic trainers, physical therapists, nurses, neuropsychologists, scientists, engineers, coaches, and officials) voted to prioritize these action items in the final Summit session. 1) Establish a national and international hockey data base for SRC at all levels, 2) eliminate body checking in Bantam youth hockey games, 3) expand a behavior modification program (Fair Play) to all youth hockey levels, 4) enforce game ejection penalties for fighting in Junior A and professional hockey leagues, 5) establish objective tests to diagnose concussion at point of care (POC), and 6) mandate baseline testing to improve concussion diagnosis for all age groups. Expedient implementation of the Summit III prioritized action items is necessary to reduce the risk, severity, and consequences of concussion in the sport of ice hockey.
Asunto(s)
Traumatismos en Atletas/epidemiología , Traumatismos en Atletas/prevención & control , Conmoción Encefálica/epidemiología , Conmoción Encefálica/prevención & control , Hockey/lesiones , Traumatismos en Atletas/diagnóstico , Traumatismos en Atletas/terapia , Conmoción Encefálica/diagnóstico , Conmoción Encefálica/terapia , Bases de Datos Factuales , Humanos , Medicina Deportiva/normas , Deportes Juveniles/normasRESUMEN
This study aimed to compare head impact exposures between practices and games in football players ages 9 to 14 years, who account for approximately 70% of all football players in the United States. Over a period of 2 seasons, 136 players were enrolled from 3 youth programs, and 49,847 head impacts were recorded from 345 practices and 137 games. During the study, individual players sustained a median of 211 impacts per season, with a maximum of 1226 impacts. Players sustained 50th (95th) percentile peak linear acceleration of 18.3 (46.9) g, peak rotational acceleration of 1305.4 (3316.6) rad·s-2, and Head Impact Technology Severity Profile of 13.7 (24.3), respectively. Overall, players with a higher frequency of head impacts at practices recorded a higher frequency of head impacts at games (P < .001, r2 = .52), and players who sustained a greater average magnitude of head impacts during practice also recorded a greater average magnitude of head impacts during games (P < .001). The youth football head impact data quantified in this study provide valuable insight into the player exposure profile, which should serve as a key baseline in efforts to reduce injury.
Asunto(s)
Traumatismos Craneocerebrales/prevención & control , Fútbol Americano/lesiones , Dispositivos de Protección de la Cabeza , Aceleración , Adolescente , Fenómenos Biomecánicos , Niño , Traumatismos Craneocerebrales/fisiopatología , Movimientos de la Cabeza/fisiología , Humanos , Masculino , Estados UnidosRESUMEN
Kinematic measurements of head impacts are sensitive to sports concussion, but not highly specific. One potential reason is these measures reflect input conditions only and may have varying degrees of correlation to regional brain tissue deformation. In this study, previously reported head impact data recorded in the field from high school and collegiate football players were analyzed using two finite element head models (FEHM). Forty-five impacts associated with immediately diagnosed concussion were simulated along with 532 control impacts without identified concussion obtained from the same players. For each simulation, intracranial response measures (max principal strain, strain rate, von Mises stress, and pressure) were obtained for the whole brain and within four regions of interest (ROI; cerebrum, cerebellum, brain stem, corpus callosum). All response measures were sensitive to diagnosed concussion; however, large inter-athlete variability was observed and sensitivity strength depended on measure, ROI, and FEHM. Interestingly, peak linear acceleration was more sensitive to diagnosed concussion than all intracranial response measures except pressure. These findings suggest FEHM may provide unique and potentially important information on brain injury mechanisms, but estimations of concussion risk based on individual intracranial response measures evaluated in this study did not improve upon those derived from input kinematics alone.
Asunto(s)
Conmoción Encefálica , Encéfalo , Fútbol Americano , Estrés Mecánico , Adolescente , Adulto , Encéfalo/patología , Encéfalo/fisiopatología , Conmoción Encefálica/diagnóstico , Conmoción Encefálica/parasitología , Conmoción Encefálica/patología , Humanos , MasculinoRESUMEN
CONTEXT: Despite the growing popularity of ice hockey among female youth and interest in the biomechanics of head impacts in sport, the head impacts sustained by this population have yet to be characterized. OBJECTIVES: To describe the number of, biomechanical characteristics of, and exposure to head impacts of female youth ice hockey players during competition and to investigate the influences of player and game characteristics on head impacts. DESIGN: Cohort study. METHODS: Twenty-seven female youth ice hockey players (mean age = 12.5 ± 0.52 years) wore instrumented ice hockey helmets during 66 ice hockey games over a 3-year period. Data specific to player, game, and biomechanical head impact characteristics were recorded. A multiple regression analysis identified factors most associated with head impacts of greater frequency and severity. RESULTS: A total of 436 total head impacts were sustained during 6924 minutes of active ice hockey participation (0.9 ± 0.6 impacts per player per game; range, 0-2.1). A higher body mass index (BMI) significantly predicted a higher number of head impacts sustained per game (P = .008). Linear acceleration of head impacts was greater in older players and those who played the forward position, had a greater BMI, and spent more time on the ice (P = .008), whereas greater rotational acceleration was present in older players who had a greater BMI and played the forward position (P = .008). During tournament games, increased ice time predicted increased severity of head impacts (P = .03). CONCLUSIONS: This study reveals for the first time that head impacts are occurring in female youth ice hockey players, albeit at a lower rate and severity than in male youth ice hockey players, despite the lack of intentional body checking.
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Atletas/psicología , Traumatismos en Atletas , Fenómenos Biomecánicos/fisiología , Conmoción Encefálica , Cabeza/fisiología , Hockey , Adolescente , Traumatismos en Atletas/epidemiología , Traumatismos en Atletas/etiología , Traumatismos en Atletas/prevención & control , Conmoción Encefálica/epidemiología , Conmoción Encefálica/etiología , Conmoción Encefálica/prevención & control , Canadá/epidemiología , Niño , Estudios de Cohortes , Femenino , Dispositivos de Protección de la Cabeza , Hockey/fisiología , Hockey/psicología , Humanos , Factores de RiesgoRESUMEN
Epidemiological evidence suggests that female athletes may be at a greater risk of concussion than their male counterparts. The purpose of this study was to examine the biomechanics of head impacts associated with diagnosed concussions in a cohort of female collegiate ice hockey players. Instrumented helmets were worn by 58 female ice hockey players from 2 NCAA programs over a three year period. Kinematic measures of single impacts associated with diagnosed concussion and head impact exposure on days with and without diagnosed concussion were evaluated. Nine concussions were diagnosed. Head impact exposure was greater in frequency and magnitude on days of diagnosed concussions than on days without diagnosed concussion for individual athletes. Peak linear accelerations of head impacts associated with diagnosed concussion in this study are substantially lower than those previously reported in male athletes, while peak rotational accelerations are comparable. Further research is warranted to determine the extent to which female athletes' biomechanical tolerance to concussion injuries differs from males.
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Traumatismos en Atletas/fisiopatología , Conmoción Encefálica/fisiopatología , Atletas , Fenómenos Biomecánicos , Femenino , Dispositivos de Protección de la Cabeza , Hockey , Humanos , UniversidadesRESUMEN
This study aimed to present currently known basic science and on-ice influences of sport-related concussion (SRC) in hockey, building upon the Ice Hockey Summit I action plan (2011) to reduce SRC. The prior summit proceedings included an action plan intended to reduce SRC. As such, the proceedings from Summit I served as a point of departure for the science and discussion held during Summit II (Mayo Clinic, Rochester, MN, October 2013). Summit II focused on (1) Basic Science of Concussions in Ice Hockey: Taking Science Forward, (2) Acute and Chronic Concussion Care: Making a Difference, (3) Preventing Concussions via Behavior, Rules, Education, and Measuring Effectiveness, (4) Updates in Equipment: Their Relationship to Industry Standards, and (5) Policies and Plans at State, National, and Federal Levels To Reduce SRC. Action strategies derived from the presentations and discussion described in these sectors were voted on subsequently for purposes of prioritization. The following proceedings include the knowledge and research shared by invited faculty, many of whom are health care providers and clinical investigators. The Summit II evidence-based action plan emphasizes the rapidly evolving scientific content of hockey SRC. It includes the most highly prioritized strategies voted on for implementation to decrease concussion. The highest-priority action items identified from the Summit include the following: (1) eliminate head hits from all levels of ice hockey, (2) change body checking policies, and (3) eliminate fighting in all amateur and professional hockey.
Asunto(s)
Agresión , Conmoción Encefálica/prevención & control , Hockey/lesiones , Hockey/legislación & jurisprudencia , Traumatismos en Atletas/etiología , Traumatismos en Atletas/prevención & control , Hockey/normas , Humanos , MinnesotaRESUMEN
OBJECTIVE: To present currently known basic science and on-ice influences of sport related concussion (SRC) in hockey, building upon the Ice Hockey Summit I action plan (2011) to reduce SRC. METHODS: The prior summit proceedings included an action plan intended to reduce SRC. As such, the proceedings from Summit I served as a point of departure, for the science and discussion held during Summit II (Mayo Clinic, Rochester MN, October, 2013). Summit II focused on Basic Science of Concussions in Ice Hockey: Taking Science Forward; (2) Acute and Chronic Concussion Care: Making a Difference; (3) Preventing Concussions via Behavior, Rules, Education and Measuring Effectiveness; (4) Updates in Equipment: their Relationship to Industry Standards and (5) Policies and Plans at State, National and Federal Levels to reduce SRC. Action strategies derived from the presentations and discussion described in these sectors were subsequently voted on for purposes of prioritization. The following proceedings include the knowledge and research shared by invited faculty, many of whom are health care providers and clinical investigators. RESULTS: The Summit II evidence based action plan emphasizes the rapidly evolving scientific content of hockey SRC. It includes the most highly prioritized strategies voted on for implementation to decrease concussion. CONCLUSIONS: The highest priority action items identified from the Summit include: 1) eliminate head hits from all levels of ice hockey, 2) change body checking policies, and 3) eliminate fighting in all amateur and professional hockey.
Asunto(s)
Conmoción Encefálica/prevención & control , Prioridades en Salud , Hockey/lesiones , Formulación de Políticas , Seguridad , Adolescente , Adulto , Factores de Edad , Agresión , Niño , Femenino , Dispositivos de Protección de la Cabeza , Humanos , Masculino , Volver al Deporte , Factores SexualesRESUMEN
Sports-related concussion is a major public health problem in the United States and yet its biomechanical mechanisms remain unclear. In vitro studies demonstrate axonal elongation as a potential injury mechanism; however, current response-based injury predictors (e.g., maximum principal strain, ε(ep)) typically do not incorporate axonal orientations. We investigated the significance of white matter (WM) fiber orientation in strain estimation and compared fiber strain (ε(n)) with ε(ep) for 11 athletes with a clinical diagnosis of concussion. Geometrically accurate subject-specific head models with high mesh quality were created based on the Dartmouth Head Injury Model (DHIM), which was successfully validated (performance categorized as "good" to "excellent"). For WM regions estimated to be exposed to high strains using a range of injury thresholds (0.09-0.28), substantial differences existed between ε(n) and ε(ep) in both distribution (Dice coefficient of 0.13-0.33) and extent (⼠5-10-fold differences), especially at higher threshold levels and higher rotational acceleration magnitudes. For example, an average of 3.2% vs. 29.8% of WM was predicted above an optimal threshold of 0.18 established from an in vivo animal study using ε(n) and ε(ep), respectively, with an average Dice coefficient of 0.14. The distribution of WM regions with high ε(n) was consistent with typical heterogeneous patterns of WM disruptions in diffuse axonal injury, and the group-wise extent at the optimal threshold matched well with the percentage of WM voxels experiencing significant longitudinal changes of fractional anisotropy and mean diffusivity (3.2% and 3.44%, respectively) found from a separate independent study. These results suggest the significance of incorporating WM microstructural anisotropy in future brain injury studies.
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Traumatismos en Atletas/patología , Conmoción Encefálica/patología , Lesión Axonal Difusa/patología , Fibras Nerviosas Mielínicas/patología , Sustancia Blanca/patología , Adolescente , Traumatismos en Atletas/complicaciones , Conmoción Encefálica/etiología , Lesión Axonal Difusa/etiología , Imagen de Difusión Tensora , Femenino , Humanos , Masculino , Adulto JovenRESUMEN
CONTEXT: Concussion injury rates in men's and women's ice hockey are reported to be among the highest of all collegiate sports. Quantification of the frequency of head impacts and the magnitude of head acceleration as a function of the different impact mechanisms (eg, head contact with the ice) that occur in ice hockey could provide a better understanding of this high injury rate. OBJECTIVE: To quantify and compare the per-game frequency and magnitude of head impacts associated with various impact mechanisms in men's and women's collegiate ice hockey players. DESIGN: Cohort study. SETTING: Collegiate ice hockey rink. PATIENTS OR OTHER PARTICIPANTS: Twenty-three men and 31 women from 2 National Collegiate Athletic Association Division I ice hockey teams. MAIN OUTCOME MEASURE(S): We analyzed magnitude and frequency (per game) of head impacts per player among impact mechanisms and between sexes using generalized mixed linear models and generalized estimating equations to account for repeated measures within players. INTERVENTION(S): Participants wore helmets instrumented with accelerometers to allow us to collect biomechanical measures of head impacts sustained during play. Video footage from 53 games was synchronized with the biomechanical data. Head impacts were classified into 8 categories: contact with another player; the ice, boards or glass, stick, puck, or goal; indirect contact; and contact from celebrating. RESULTS: For men and women, contact with another player was the most frequent impact mechanism, and contact with the ice generated the greatest-magnitude head accelerations. The men had higher per-game frequencies of head impacts from contact with another player and contact with the boards than did the women (P < .001), and these impacts were greater in peak rotational acceleration (P = .027). CONCLUSIONS: Identifying the impact mechanisms in collegiate ice hockey that result in frequent and high-magnitude head impacts will provide us with data that may improve our understanding of the high rate of concussion in the sport and inform injury-prevention strategies.