Impact locations and concussion outcomes in high school football player-to-player collisions

Comparison of Kinematics for Head Impacts Initiated by Helmets and Shoulder Pads Among High School American Football Athletes

Helmets and shoulder pads are required equipment intended to protect American football athletes by attenuating collision forces during participation. Surprisingly, research differentiating kinematics from head impacts initiated by helmets from those initiated by shoulder pads among adolescent athletes has not been completed. The current study's purpose was to determine the effects of equipment on head impact kinematics. Sixty-nine male American football athletes from three high schools wore helmets equipped with Head Impact Telemetry (HIT) System instrumentation to quantify peak linear (g) and rotational (rad/s2) accelerations. Data were extracted for video-confirmed impacts during two competitions. Separate multivariable linear regressions using ordinary least squares were conducted to determine if equipment type (helmet vs. shoulder pad) was associated with log-transformed linear and rotational accelerations. In total, 1150 video-confirmed impacts involved helmet (N = 960) or shoulder pad (N = 190) initiated contact. Linear (p = 0.809) and rotational (p = 0.351) acceleration were not associated with equipment type. Head impact kinematics were similar between impacts initiated by either helmets or shoulder pads and suggests an opponent's shoulder pads and helmet can deliver comparable forces to the struck player. Equipment manufacturers may need to consider the unintended role shoulder pads may contribute to head injury risk.

Longitudinal, prospective study of head impacts in male high school football players

INTRODUCTION

Repetitive, subconcussive events may adversely affect the brain and cognition during sensitive periods of development. Prevention of neurocognitive consequences of concussion in high school football is therefore an important public health priority. We aimed to identify the player positions and demographic, behavioral, cognitive, and impact characteristics that predict the frequency and acceleration of head impacts in high school football players.

METHODS

In this prospective study, three cohorts of adolescent male athletes (N = 53, 28.3% Hispanic) were recruited over three successive seasons in a high school American football program. Demographic and cognitive functioning were assessed at baseline prior to participating in football. Helmet sensors recorded impact frequency and acceleration. Each head impact was captured on film from five different angles. Research staff verified and characterized on-field impacts. Player-level Poisson regressions and year-level and impact-level linear mixed-effect models were used to determine demographic, behavioral, cognitive, and impact characteristics as predictors of impact frequency and acceleration.

RESULTS

4,678 valid impacts were recorded. Impact frequency positively associated with baseline symptoms of hyperactivity-impulsivity [β(SE) = 1.05 impacts per year per unit of symptom severity (1.00), p = 0.01] and inattentiveness [β(SE) = 1.003 impacts per year per T-score unit (1.001), p = 0.01]. Compared to quarterbacks, the highest acceleration impacts were sustained by kickers/punters [β(SE) = 21.5 g's higher (7.1), p = 0.002], kick/punt returners [β(SE) = 9.3 g's higher (4.4), p = 0.03], and defensive backs [β(SE) = 4.9 g's higher (2.5), p = 0.05]. Impacts were more frequent in the second [β(SE) = 33.4 impacts (14.2), p = 0.02)] and third [β(SE) = 50.9 impacts (20.1), p = 0.01] year of play. Acceleration was highest in top-of-the-head impacts [β(SE) = 4.4 g's higher (0.8), p<0.001].

CONCLUSION

Including screening questions for Attention-Deficit/Hyperactivity Disorder in pre-participation evaluations can help identify a subset of prospective football players who may be at risk for increased head impacts. Position-specific strategies to modify kickoffs and correct tackling and blocking may also reduce impact burden.

Youth Tackle Football Head-Impact Estimation by Players and Parents: Is the Perception the Reality?

CONTEXT

With growing concerns surrounding exposure to head impacts in youth tackle football, players and parents must understand the exposure level when assenting and consenting to participate.

OBJECTIVE

To determine whether youth football players and parents could estimate on-field head-impact frequency, severity, and location.

DESIGN

Prospective cohort study.

SETTING

Football field.

PATIENTS OR OTHER PARTICIPANTS

We administered a 10-question head-impact estimation tool to parents (n = 23; mean age = 36.5 years [95% CI = 31.7, 37.3 years]) and players (n = 16 boys; mean age = 11.1 years [95% CI = 10.3, 11.8 years]).

MAIN OUTCOME MEASURE(S)

Player on-field head-impact exposure was captured using the Triax SIM-G system. We determined the accuracy between player and parent estimates relative to on-field head-impact exposures using κ and weighted κ values.

RESULTS

Youth tackle football players and parents did not accurately estimate on-field head-impact frequency (κ range = -0.09 to 0.40), severity (κ range = -0.05 to 0.34), or location (κ range = -0.30 to 0.13). Players and parents overestimated head-impact frequency in practices but underestimated the frequency in games. Both groups overestimated head-impact severity, particularly in games. Most players and parents underestimated the number of head impacts to the top of the head, particularly during practices.

CONCLUSIONS

Underestimations of head-impact frequency in games and to the top of the head suggest that informed consent processes aimed at educating players and parents should be improved. Overestimations of head-impact frequency in practices and severity may explain declining rates of youth tackle football participation.

Head Impact Exposure in Youth and Collegiate American Football

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.

National Athletic Trainers' Association Position Statement: Reducing Intentional Head-First Contact Behavior in American Football Players

OBJECTIVE

To provide evidence-based recommendations for reducing the prevalence of head-first contact behavior in American football players with the aim of reducing the risk of head and neck injuries.

BACKGROUND

In American football, using the head as the point of contact is a persistent, well-documented, and direct cause of catastrophic head and cervical spine injury. Equally concerning is that repeated head-impact exposures are likely to result from head-first contact behavior and may be associated with long-term neurocognitive conditions such as dementia, depression, and chronic traumatic encephalopathy.

CONCLUSIONS

The National Athletic Trainers' Association proposes 14 recommendations to help the certified athletic trainer, allied health care provider, coach, player, parent, and broader community implement strategies for reducing the prevalence of head-first contact in American football.

Association of Pediatric Hearing Quality and Sports Participation: A Population-Based Study

Sports-related injuries, such as concussion, during childhood may result in considerable morbidity, including a range of negative developmental consequences. Auditory dysfunction is generally recognized to be a possible sequela of sports-related concussion; however, few epidemiologic studies have quantified the association between hearing quality and sports-related activity in the pediatric population. The National Health and Nutrition Examination Survey for the 2015-2016 cycle was utilized to determine the association of sports activities and hearing quality. Subjective abnormal hearing quality was more frequent among children who played football than those that did not (36.5% vs 26.8%; odds ratio, 1.56 [95% CI, 1.23-2.00]; P = .001). Other sports, such as basketball and soccer, did not have this association with hearing quality (P = .496 and P = .852, respectively). Our findings suggest a notable association between practice of a potentially high concussion sport and hearing quality. Children practicing football are 1.56 times more likely to report abnormal hearing quality.Level of Evidence: 4.

Head Games: A Systematic Review and Meta-analysis Examining Concussion and Head Impact Incidence Rates, Modifiable Risk Factors, and Prevention Strategies in Youth Tackle Football

OBJECTIVES

The aims were to (1) examine the rates and mechanisms of concussion and head impact in youth football (high school level or younger); (2) identify modifiable risk factors for concussion and head impact; and (3) evaluate the effectiveness of prevention strategies in tackle football at any level.

METHODS

Nine databases (CINAHL Plus with Full Text; Cochrane Central Register of Controlled Trials; EMBASE; ERIC; Ovid MEDLINE(R) and Epub Ahead of Print, In-Process & Other Non-Indexed Citations and Daily; ProQuest Dissertations & Theses Global Database; PsycINFO; Scopus; and SPORTDiscus with Full Text) were searched using the search strategy focusing on four main concepts: concussion/head impact, tackle football, modifiable risk factors, and primary prevention. Two reviewers completed title, abstract, and full-text screening as well as risk of bias assessment (using the Downs and Black checklist), with a third author available to resolve any disagreements.

MAIN RESULTS

After removing duplicates, 1911 articles were returned. Fifty-eight articles were included in the review and 20 in the meta-analysis. The overall combined rates of concussion (including game and practice-related concussion) based on the meta-analysis were 0.78 concussions/1000 athlete exposures [95% confidence interval (CI) 0.67-0.89] for high school football (ages 13-19) and 1.15 concussions/1000 athlete exposures (95% CI 0.89-1.41) for minor football players (ages 5-15). There is evidence that contact training and practice contact restrictions have reduced the rate of head impacts and concussion. Heads Up Football (an intervention focused on coach education and contact training) has been shown to reduce the rate of concussion by 32% and head impacts by 38% amongst high school football players. Limiting contact practices in high schools to 2 days per week reduced practice head impacts per player-season by 42%, and limiting full contact in practice to 75 min per week in the second week of the season and 60 min in week 3 and beyond resulted in a 54% decrease in the practice-related concussion rate (p = 0.003).

CONCLUSIONS

This review identified a critical need for interventions to address the high rates of concussion and head impact in youth football. To date, contact training and contact restrictions have the strongest evidence supporting their effectiveness at reducing these rates. Future research should use consistent concussion definitions and validated injury surveillance systems, and ensure complete reporting of participant characteristics and sampling details. Prospero ID CRD42020193775.

Data-Driven Risk Classification of Concussion Rates: A Systematic Review and Meta-Analysis

BACKGROUND

Concussion is a growing public health concern and generating concussion prevention programs depends on identifying high-risk sports and characteristics. Identifying the roles of sport, sex, and participation level (e.g., high school versus collegiate athletics) in concussion risk would facilitate more informed decision-making regarding sports participation and generate better targeted prevention strategies.

OBJECTIVES

The current study's objectives were to: (1) determine the magnitude and hierarchy of sports-related concussion (SRC) risk across an array of events and (2) evaluate the modifying roles of sex, participation level, and session type on SRC rates.

METHODS

A literature search was conducted on PubMed, searching concussion studies published between 2001 and December 2019. Inclusion criteria for studies required: (1) concussion occurred during sport, (2) that the SRC was clinically diagnosed, and (3) athlete exposures and concussions could be extracted or estimated. A study was excluded if it: (1) was not an original research article, (2) was not written in English language, (3) was an animal study, (4) did not have enough data to calculate SRC rates, (5) included professional or youth sample, and/or (6) contained data collected prior to 2001. The meta-analysis and meta-regression analyses were fit using a random effects model.

RESULTS

Search results returned 2695 unique research articles, with 83 studies included in analyses. Sport, sex, participation level, and session type all significantly influenced SRC rates. Overall, rugby had the highest concussion rate and was classified as the highest risk sport (28.25 concussions per 10,000 athlete exposures). Overall, females had a higher concussion rate than males. Only lacrosse demonstrated a higher concussion rate for males compared to females. Collegiate athletes had higher concussion rates than high school athletes. Games were associated with 2.01 more concussions per 10,000 AEs than practices.

CONCLUSIONS

This meta-analysis demonstrated rugby has the highest concussion risk, followed by American Football, ice hockey, and wrestling. Concussion risk was influenced by sport, sex, participation, and session. Identifying the factors and environments that influence concussion risk can facilitate risk reduction and prevention strategies.

Network Analysis of Sport-Related Concussion Research During the Past Decade (2010-2019)

CONTEXT

Research into sport-related concussion (SRC) has grown substantially over the past decade, yet no authors to date have synthesized developments over this critical time period.

OBJECTIVE

To apply a network-analysis approach in evaluating trends in the SRC literature using a comprehensive search of original, peer-reviewed research articles involving human participants published between January 1, 2010, and December 15, 2019.

DESIGN

Narrative review.

MAIN OUTCOME MEASURE(S)

Bibliometric maps were derived from a comprehensive search of all published, peer-reviewed SRC articles in the Web of Science database. A clustering algorithm was used to evaluate associations among journals, organizations or institutions, authors, and key words. The online search yielded 6130 articles, 528 journals, 7598 authors, 1966 organizations, and 3293 key words.

RESULTS

The analysis supported 5 thematic clusters of journals: (1) biomechanics/sports medicine (n = 15), (2) pediatrics/rehabilitation (n = 15), (3) neurotrauma/neurology/neurosurgery (n = 11), (4) general sports medicine (n = 11), and (5) neuropsychology (n = 7). The analysis identified 4 organizational clusters of hub institutions: (1) University of North Carolina (n = 19), (2) University of Toronto (n = 19), (3) University of Michigan (n = 11), and (4) University of Pittsburgh (n = 10). Network analysis revealed 8 clusters for SRC key words, each with a central topic area: (1) epidemiology (n = 14), (2) rehabilitation (n = 12), (3) biomechanics (n = 11), (4) imaging (n = 10), (5) assessment (n = 9), (6) mental health/chronic traumatic encephalopathy (n = 9), (7) neurocognition (n = 8), and (8) symptoms/impairments (n = 5).

CONCLUSIONS

The findings suggest that during the past decade SRC research has (1) been published primarily in sports medicine, pediatric, and neuro-focused journals, (2) involved a select group of researchers from several key institutions, and (3) concentrated on new topical areas, including treatment or rehabilitation and mental health.

Post-concussion symptoms in sports-related mild traumatic brain injury compared to non-sports-related mild traumatic brain injury

OBJECTIVES

To compare post-concussion symptoms in patients who sustained a sports-related mild traumatic brain injury (TBI) to those with non-sports-related mild TBI at 7 and 90 days post-injury.

METHODS

This prospective multicentre cohort study took place in seven Canadian Emergency Departments (ED). Non-hospitalized patients aged ≥ 14 years with a documented mild TBI that occurred ≤ 24 h of ED visit and a Glasgow Coma Scale score ≥ 13 were included. Main outcome measure was the presence of ≥ 3 symptoms on the Rivermead Post-concussion Questionnaire at 90 days post-injury. Secondary outcomes were the prevalence of (1) individual Rivermead Post-concussion Questionnaire symptom, (2) total Rivermead Post-concussion Questionnaire score ≥ 21 and (3) return to normal daily activities. Adjusted risk ratios (RR) were calculated.

RESULTS

1727 patients were included, 363 (21.0%) sustained a sports-related mild TBI. Similar proportions of patients with ≥ 3 symptoms, a Rivermead Post-concussion Questionnaire score ≥ 21 and those who returned to their normal daily activities were observed at 7 and 90 days post-injury. Sports-related mild TBI patients were at higher risk of poor concentration [RR: 1.3 (95% CI 1.05-1.54)] and non-return to sports activities [RR: 2.2 (95% CI 1.69-2.94)] at 7 days post-injury. At 90 days, sports-relate -mild TBI patients reported less fatigue [RR: 0.7 (95% CI 0.51-0.98)] and feeling of dizziness [RR: 0.6 (95% CI 0.35-0.99)].

CONCLUSION

Patients who sustained sports-related mild TBI could be at lower risk of experiencing symptoms such as fatigue and dizziness 90 days post-injury. Clinicians should be mindful that non-sports-related mild TBI patients may experience more post-concussion symptoms and that the level of physical activity may influence the patient's rehabilitation.

Development of an Eco-Friendly Head Impact Protection Device

Nowadays, the number of people practising contact sports has increased. In many of them, using head protective equipment is not mandatory, even if the use of headbands could increase the level of safety regarding several types of traumatic brain injuries. Many commercial solutions are currently available, based on plastic-based foams providing a decent level of protection and comfort to the user. This work introduces the use of agglomerated cork as an eco-friendly alternative to synthetic foams but at least keeping safety levels. Cork is a natural cellular material that has been showing excellent crashworthiness properties. In this study, cork agglomerate density is carefully chosen to be incorporated into a protective headband. Results are compared against three other commercial headbands. For each one, the risk of brain injury was analysed for different injury thresholds and impact energies. The results clearly demonstrate that the cork-based apparel may provide comparable, and in some cases, better performances, outlasting the commercial ones.

Injury Rate in TackleBar Football

Background:

As football comes under greater scrutiny because of concussions and other injuries, many people are searching for safer alternatives, especially for youth athletes. The injury rate in TackleBar football, one such alternative, is not currently known.

Purpose:

To describe TackleBar football and calculate its injury rate over a single season to compare it with both traditional tackle and flag football.

Study Design:

Descriptive epidemiology study.

Methods:

TackleBar football was described, and injuries of male athletes (age range, 9-14 years) participating in TackleBar football were tracked over the course of a season (August 5 through October 27, 2018) and compared with published injury rates for traditional tackle and flag football.

Results:

The overall injury rate of TackleBar football was found to be 0.31 per 1000 athlete-exposures (AEs), which is lower than youth tackle (2.25-2.60/1000 AEs) and flag (5.77/1000 AEs) football.

Conclusion:

TackleBar football may represent a reasonable alternative to tackle and flag football with regard to injuries.

Evaluation of Benign Paroxysmal Positional Vertigo in American Football Players

OBJECTIVES

The aim of this investigation was to evaluate the association between posterior channel benign paroxysmal positional vertigo (BPPV) and trauma that is frequently experienced by American football players.

MATERIALS AND METHODS

Participants were classified into the following two groups: (1) a study group consisting of 63 male participants aged 18-30 years who had been playing American football for more than 2 years and (2) a control group consisting of 49 male participants aged 18-27 years with no history of otologic/vestibular disease or acute/chronic trauma. Trauma, age, total duration of playing American football, and weekly training hours of subjects in the study group were analyzed to determine any relationship with BPPV occurrence. We performed otologic, audiologic, and vestibular assessments of pure sound audiometry, tympanometry, tandem walking test with eyes open and eyes closed, Romberg, head shaking, roll, and Dix-Hallpike tests to all participants.

RESULTS

A positive correlation between the total years of American football played and posterior channel BPPV frequency was observed in the study group. In addition, increasing weekly hours of training was shown to further increase the risk of BPPV. A total of 16 out of 63 athletes experienced BPPV, whereas none of the participants in the control group experienced BPPV. All participants completed the Vertigo Symptom Scale, which revealed that vertigo did not cause any significant negative impact on their training routine and activities of daily living.

CONCLUSION

Our results indicate that the weekly training hours and total years of training with American football increase posterior channel BPPV frequency.

A helmetless-tackling intervention in American football for decreasing head impact exposure: A randomized controlled trial

OBJECTIVES

To evaluate a behavioral intervention to reduce head impact exposure in youth playing American football.

DESIGN

Nested randomized controlled trial.

METHODS

Participants, ages 14-17 years, wore head impact sensors (SIM-G™) during two seasons of play. Those randomized to the intervention group underwent weekly tackling/blocking drills performed without helmets (WoH) and shoulder pads while the control group trained as normal, matching frequency and duration. Research personnel provided daily oversight to maintain fidelity. Head impact frequency (≥10g) per athlete exposure (ImpAE) was analyzed over time (two 11-week seasons) using mixed effect models or ANCOVA. Secondary outcomes included exposure-type (training, game) and participation level (entry-level versus upper-level secondary education).

RESULTS

One-hundred fifteen participants (59 WoH, 56 control) met compliance criteria, contributing 47,382 head impacts and 10,751 athlete exposures for analysis. WoH had fewer ImpAE during games compared to control participants at weeks 4 (p=0.0001 season 1, p=0.0005 season 2) and 7 (p=0.0001 both seasons). Upper-level WoH participants had less ImpAE during games than their matched controls at weeks 4 (p=0.017 and p=0.026) and 7 (p=0.037 and p=0.014) in both seasons, respectively. Upper-level WoH also had fewer ImpAE during training at week 7 (p=0.015) in season one.

CONCLUSIONS

Tackling and blocking drills performed without a helmet during training reduced the frequency of head impacts during play, especially during games. However, these differences disappeared by the end of the season. Future research should explore the frequency of behavioral intervention and a dose-response relationship considering years of player experience.

TRIAL REGISTRATION

ClinicalTrials.gov # NCT02519478.

Head Impact Locations in U.S. High School Boys' and Girls' Soccer Concussions, 2012/13-2015/16

This study describes concussions and concussion-related outcomes sustained by high school soccer players by head impact location, sex, and injury mechanism. Data were obtained for the 2012/13-2015/16 school years from the National High School Sports-Related Injury Surveillance System, High School RIO™. This Internet-based sports injury surveillance system captures data reported by athletic trainers from an annual average of 162 U.S. high schools. Data were analyzed to describe circumstances of soccer concussion (e.g., symptomology, symptom resolution, and return-to-play time) by impact location (i.e., front- [face included], back-, side-, and top-of-the-head) and sex. Most concussions were from front-of-the-head impacts (boys, 30.5%; girls, 34.0%). Overall, 4.1 ± 2.2 and 4.6 ± 2.3 symptoms were reported in boys and girls, respectively. In boys, symptom frequency was not associated with head impact location (p = 0.66); an association was found in girls (p = 0.02), with the highest symptom frequency reported in top-of-the-head impacts (5.4 ± 2.2). Head impact location was not associated with symptom resolution time (boys, p = 0.21; girls, p = 0.19) or return-to-play time (boys, p = 0.18; girls, p = 0.07). Heading was associated with 28.0% and 26.5% of concussions in boys and girls, respectively. Most player-player contact concussions during heading occurred from side-of-the-head impacts (boys, 49.4%; girls, 43.2%); most heading-related ball contact concussions occurred from front-of-the-head (boys, 41.4%; girls, 42.6%) and top-of-the-head (boys, 34.5%; girls, 36.9%) impacts. Head impact location was generally independent of symptom resolution time, return-to-play time, and recurrence among high school soccer concussions. However, impact location may be associated with reported symptom frequency. Further, many of these clinical concussion descriptors were associated with sex.

What the research says about concussion risk factors and prevention strategies for youth sports: A scoping review of six commonly played sports

INTRODUCTION

Given the growing research on potential adverse outcomes related to concussion and other serious brain injuries and the increased susceptibility for concussion among youth athletes, primary prevention is vital to protect the health and safety of this population. The purpose of this study is to summarize the current research on risk factors and primary concussion prevention strategies focused on specific youth sports, and to identify research gaps.

METHODS

A literature search was conducted using six electronic databases. A scoping review method was used to identify studies that addressed risk factors or primary concussion prevention strategies focused on youth athletes (ages 5-18 years) in six sports (football, ice hockey, soccer, lacrosse, basketball, and wrestling).

RESULTS

Of the 18 publications identified, the publications focused on risk factors (N = 11), policy (N = 1), rule changes (N = 3), education (N = 2), equipment (N = 2), and playing technique (N = 0). Some articles had information related to multiple topics.

CONCLUSIONS

Current research on concussion prevention has primarily been focused on risk factors. There are a dearth of studies that examine primary concussion prevention in sports. When studies do exist, most focus on football and ice hockey. Only a small number of studies focus solely on risk factors or primary prevention in soccer, lacrosse, basketball, and wrestling-all sports in which concussions are common. Practical applications: This scoping review summarizes current research on concussion risk factors and primary prevention strategies in specific sports focused on youth athletes and identifies research gaps to help inform future efforts.

Video Analysis of Reported Concussion Events in the National Football League During the 2015-2016 and 2016-2017 Seasons

BACKGROUND

Concussions in American football remain a high priority of sports injury prevention programs. Detailed video review provides important information on causation, the outcomes of rule changes, and guidance on future injury prevention strategies.

PURPOSE

Documentation of concussions sustained in National Football League games played during the 2015-2016 and 2016-2017 seasons, including consideration of video views unavailable to the public.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

All reported concussions were reviewed with all available video footage. Standardized terminology and associated definitions were developed to describe and categorize the details of each concussion.

RESULTS

Cornerbacks sustained the most concussions, followed by wide receivers, then linebackers and offensive linemen. Half (50%) of concussions occurred during a passing play, 28% during a rushing play, and 21% on a punt or kickoff. Tackling was found to be the most common activity of concussed players, with the side of the helmet the most common helmet impact location. The distribution of helmet impact source-the object that contacted the concussed player's helmet-differed from studies of earlier seasons, with a higher proportion of helmet-to-body impacts (particularly shoulder) and helmet-to-ground impacts and with a lower proportion of helmet-to-helmet impacts. Helmet-to-ground concussive impacts were notable for the high prevalence of impacts to the back of the helmet and their frequency during passing plays.

CONCLUSION

Concussion causation scenarios in the National Football League have changed over time.

CLINICAL RELEVANCE

The results of this study suggest the need for expanded evaluation of concussion countermeasures beyond solely helmet-to-helmet test systems, including consideration of impacts with the ground and with the body of the opposing player. It also suggests the possibility of position-specific countermeasures as part of an ongoing effort to improve safety.

Effect of Impact Mechanism on Head Accelerations in Men's Lacrosse Athletes

Quantifying head impacts is a vital component to understanding and preventing head trauma in sport. Our objective was to establish the frequency and magnitude of head impact mechanisms in men's lacrosse athletes. Eleven male lacrosse athletes wore xPatch sensors during activity. Video footage of practices and games was analyzed to verify impacts and code them with impact mechanisms. The authors calculated incidence rates (IRs) per 1000 exposures with corresponding 95% confidence intervals (CIs) and used multivariate analysis of variances to compare the linear (g) and rotational (rad/s²) accelerations between mechanisms. A total of 167 head impacts were successfully verified and coded with a mechanism using video footage during 542 total exposures. The highest IR was head to body (IR = 118.08; 95% CI, 89.15-147.01), and the lowest was head to ball (IR = 3.69; 95% CI, 0-8.80) (incidence rate ratio = 32.00; 95% CI, 67.83-130.73). Analysis indicated that impact mechanism failed to significantly alter the combined dependent variables (multivariate F_10,306 = 1.79, P = .06, η² = .06, 1-β = 0.83). While head to head, body to head, and stick to head mechanisms are penalty-inducing offenses in men's lacrosse, head to ground, head to ball, and combination impacts have similar head accelerations. If penalties and rules are created to protect players from traumatic head injury, the authors recommend stricter enforcement.

Motion analysis evaluation of adolescent athletes during dual-task walking following a concussion: A multicenter study

BACKGROUND

Research suggests that dynamic balance in adolescents is compromised following concussion and may worsen if patients return to sport (RTS) too soon. Understanding if there are ongoing dynamic balance deficits in adolescents at the time of RTS clearance would determine if more complex motor tasks are necessary to facilitate safe RTS decisions.

RESEARCH QUESTION

The purpose of this study was to determine if there were remaining dynamic balance deficits in concussed adolescents at the time of clearance for RTS.

METHODS

Sixteen concussed adolescent athletes (age 14.6 ± 1.8 years; 9 males; 57 ± 46 days post injury) performed a simple walking task as well as two split attention gait tasks (reciting months backwards and audio Stroop). The center of mass (COM) movement and walking velocity during these tasks was compared to a control group of 15 healthy non-concussed adolescent athletes (age 13.8 ± 1.4 years; 9 male).

RESULTS

The results indicated that there were no statistically significant differences between the two groups for any of the tasks. Height-normalized walking speed did not differ between groups during walking alone (control: 0.757 ± 0.119, concussed: 0.739 ± 0.108, p = 0.34), with the recitation task (control: 0.555 ± 0.095, concussed: 0.557 ± 0.143, p = 0.72), or with the Stroop task (control: 0.589 ± 0.129, concussed: 0.567 ± 0.141, p = 0.43). Similarly, height-normalized medial-lateral COM displacement did not differ between groups during walking alone (control: 0.027 ± 0.007, concussed: 0.028 ± 0.007, p = 0.98, with the recitation task (control: 0.037 ± 0.012, concussed: 0.0.037 ± 0.016, p = 0.82), or with the Stroop task (control: 0.032 ± 0.014, concussed: 0.033 ± 0.009, p = 0.891).

SIGNIFICANCE

These findings indicate that the patients were returned to sport when their dynamic balance was similar to controls suggesting that this cohort had recovered from their concussion. However, large variability in dynamic balance measures in both the patient and control groups may reflect ongoing neuromuscular development and requires further exploration.

Acute concussion: making the diagnosis and state of the art management

PURPOSE OF REVIEW

Concussion is an increasingly common injury in children. We aim to review the basic epidemiology and management of acute concussion and highlight recent studies that have contributed to our understanding of care for this injury.

RECENT FINDINGS

While concussion is considered a 'mild' form of traumatic brain injury, recent evidence suggests that as many as 30% of children are still symptomatic 1 month after injury. Although there is increasing interest in finding objective measures of injury and recovery, emerging imaging and serum biomarkers are not ready for routine clinical use. Identification of children at risk for prolonged symptoms is vital. Prolonged rest after injury may worsen outcomes.

SUMMARY

Concussion is a common injury in children. Objective measures of injury and recovery are needed, as are targeted therapies to mitigate the risk of prolonged recovery after injury.

The Influence of Heavier Football Helmet Faceguards on Head Impact Location and Severity

OBJECTIVE

To determine whether players with heavier faceguards have increased odds of sustaining top of the head impacts and head impacts of higher severity.

DESIGN

Cohort study.

SETTING

On-field.

PARTICIPANTS

Thirty-five division I collegiate football players.

INTERVENTIONS

Faceguard mass was measured. Head impact location and severity (linear acceleration [gravity], rotational acceleration [radian per square second], and Head Impact Technology severity profile [unitless]) were captured for 19 379 total head impacts at practices using the Head Impact Telemetry System.

MAIN OUTCOME MEASURES

Players' faceguards were categorized as either heavier (>480 g) or lighter (≤480 g) using a median split. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed for sustaining top of the head impacts between faceguard groups using a random intercepts generalized logit model. We compared head impact severity between groups using random intercepts general linear models (α = 0.05). Player position was included in all models.

RESULTS

Overall, the 4 head impact locations were equally distributed across faceguard groups (F(3,26) = 2.16, P = 0.117). Football players with heavier faceguards sustained a higher proportion impacts to the top of the head (24.7% vs 17.5%) and had slightly increased odds of sustaining top (OR, 1.72; 95% CI, 1.01-2.94) head impacts rather than front of the head impacts.

CONCLUSIONS

Football players wearing heavier faceguards might be slightly more prone to sustaining a higher proportion of top of the head impacts, suggesting that greater faceguard mass may make players more likely to lower their head before collision. Individuals involved with equipment selection should consider the potential influence of faceguard design on head impact biomechanics when recommending the use of a heavier faceguard.

Descriptive Characteristics of Concussions in National Football League Games, 2010-2011 to 2013-2014

BACKGROUND

Despite a high reported incidence rate of concussion, little is known about the on-field characteristics of injurious head impacts in National Football League (NFL) games.

PURPOSE

To characterize on-field features (location, player position, and time during game) and biomechanical features (anticipation status, closing distance, impact location and type) associated with concussions in NFL games over a 4-season period (2010-2011 to 2013-2014).

STUDY DESIGN

Descriptive epidemiology study.

METHODS

We analyzed video of a subset of reported, in-game concussions for the 2010-2011 to 2013-2014 seasons. These videos represented a sample of injuries that were diagnosed and reported on the same day and that could be clearly associated with an in-game collision as captured on video. We determined anticipation status, closing distance, impact location on the injured player's helmet, and impact type (helmet-to-helmet, helmet-to-body, or helmet-to-ground). Associations between these variables were analyzed by use of descriptive statistics and tests of association.

RESULTS

A total of 871 diagnosed concussions were reported as occurring during NFL preseason, regular season, and postseason games for the 2010-2011, 2011-2012, 2012-2013, and 2013-2014 seasons. A total of 1324 games were played during this period, giving a concussion incidence rate of 0.658 per game (95% CI, 0.61-0.70). From the video-reviewed subset (n = 429; 49.3%), the majority of injurious impacts occurred with good anticipation (57.3%) and <10 yards of closing distance (59.0%). An association was found between anticipation status and play type ([Formula: see text] = 27.398, P < .001), largely because injuries occurring on pass plays were more likely to be poorly anticipated than injuries during run plays (43.0% vs 21.4%; [Formula: see text] = 14.78, P < .001). Kick returns had the greatest proportion of well-anticipated impacts (78%) and the greatest proportion of impacts with ≥10 yards of closing distance (80%). The type of impact was approximately equally divided between helmet-to-helmet, helmet-to-body, and helmet-to-ground types. The impact location was broadly distributed over the helmet of the injured player.

CONCLUSION

In-game concussions in the NFL occurred through a diverse variety of mechanisms, surprisingly tended to be well-anticipated, and, also surprisingly, occurred with <10 yards of closing distance. The impacts causing concussion were broadly distributed over the helmet. More concussions occurred during the second half of game play, but we do not have evidence to explain this finding.

Olfactory Function and Associated Clinical Correlates in Former National Football League Players

Professional American football players incur thousands of repetitive head impacts (RHIs) throughout their lifetime. The long-term consequences of RHI are not well characterized, but may include olfactory dysfunction. RHI has been associated with changes to brain regions involved in olfaction, and olfactory impairment is common after traumatic brain injury. Olfactory dysfunction is a frequent early sequelae of neurodegenerative diseases (e.g., Alzheimer's disease), and RHI is associated with the neurodegenerative disease, chronic traumatic encephalopathy (CTE). We examined olfaction, and its association with clinical measures, in former National Football League (NFL) players. Ninety-five former NFL players (ages 40-69) and 28 same-age controls completed a neuropsychological and neuropsychiatric evaluation as part of a National Institutes of Health-funded study. The Brief Smell Identification Test (B-SIT) assessed olfaction. Principal component analysis generated a four-factor structure of the clinical measures: behavioral/mood, psychomotor speed/executive function, and verbal and visual memory. Former NFL players had worse B-SIT scores relative to controls (p = 0.0096). A B-SIT cutoff of 11 had the greatest accuracy (c-statistic = 0.61) and specificity (79%) for discriminating former NFL players from controls. In the former NFL players, lower B-SIT scores correlated with greater behavioral/mood impairment (p = 0.0254) and worse psychomotor speed/executive functioning (p = 0.0464) after controlling for age and education. Former NFL players exhibited lower olfactory test scores relative to controls, and poorer olfactory test performance was associated with worse neuropsychological and neuropsychiatric functioning. Future work that uses more-comprehensive tests of olfaction and structural and functioning neuroimaging may improve understanding on the association between RHI and olfaction.

Update on the Epidemiology of Concussion/Mild Traumatic Brain Injury

Mild traumatic injuries to the brain (e.g., concussion) are common and have been recognized since antiquity, although definitions have varied historically. Nonetheless, studying the epidemiology of concussion helps clarify the overall importance, risk factors, and at-risk populations for this injury. The present review will focus on recent findings related to the epidemiology of concussion including definition controversies, incidence, and patterns in the population overall and in the military and athlete populations specifically. Finally, as this is an area of active research, we will discuss how future epidemiologic observations hold promise for gaining greater clarity about concussion and mild traumatic brain injury.

Neurologic Care in Concussion and Post-Concussive Encephalopathy

Concussion has become a more recent "medical fad" with a lot of media coverage and hence an increasing incidence. According to the Center for Disease Control (CDC) and Prevention there are estimates of as many as 3.8 million sport-related traumatic brain injuries occurring annually (Centers for Disease Control and Prevention, 2007). Given these numbers, concussion care will require that both primary and specialist physicians feel comfortable in its management. This article will discuss the pathophysiology, epidemiology, clinical evaluation, therapies and prognosis in patients with concussion. The complex and chronic symptoms after a concussion and their management will be highlighted. Appropriate concussion care is essential for improving both the long and short term outcomes in adolescent athletes. There is an important role for the neurologist in improving the outcome in these athletes.

Epidemiology of Sports-Related Concussions in National Collegiate Athletic Association Athletes From 2009-2010 to 2013-2014: Symptom Prevalence, Symptom Resolution Time, and Return-to-Play Time

BACKGROUND

Limited data exist among collegiate student-athletes on the epidemiology of sports-related concussion (SRC) outcomes, such as symptoms, symptom resolution time, and return-to-play time.

PURPOSE

This study used the National Collegiate Athletic Association (NCAA) Injury Surveillance Program (ISP) to describe the epidemiology of SRC outcomes in 25 collegiate sports.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

SRC data from the NCAA ISP during the 2009-2010 to 2013-2014 academic years were analyzed regarding symptoms, time to resolution of symptoms, and time to return to play. Findings were also stratified by sex in sex-comparable sports (ie, ice hockey, soccer, basketball, lacrosse, baseball/softball) and whether SRCs were reported as recurrent.

RESULTS

Of the 1670 concussions reported during the 2009-2010 to 2013-2014 academic years, an average (±SD) of 5.29 ± 2.94 concussion symptoms were reported, with the most common being headache (92.2%) and dizziness (68.9%). Most concussions had symptoms resolve within 1 week (60.1%); however, 6.2% had a symptom resolution time of over 4 weeks. Additionally, 8.9% of concussions required over 4 weeks before return to play. The proportion of SRCs that required at least 1 week before return to play increased from 42.7% in 2009-2010 to 70.2% in 2013-2014 (linear trend, P < .001). Within sex-comparable sports analyses, the average number of symptoms and symptom resolution time did not differ by sex. However, a larger proportion of concussions in male athletes included amnesia and disorientation; a larger proportion of concussions in female athletes included headache, excess drowsiness, and nausea/vomiting. A total of 151 SRCs (9.0%) were reported as recurrent. The average number of symptoms reported with recurrent SRCs (5.99 ± 3.43) was greater than that of nonrecurrent SRCs (5.22 ± 2.88; P = .01). A greater proportion of recurrent SRCs also resulted in a long symptom resolution time (14.6% vs 5.4%, respectively; P < .001) and long return-to-play time (21.2% vs 7.7%, respectively; P < .001) compared with nonrecurrent SRCs.

CONCLUSION

Trends in return-to-play time may indicate changing concussion management practices in which team medical staff members withhold players from participation longer to ensure symptom resolution. Concussion symptoms may differ by sex and recurrence. Future research should continue to examine the trends and discrepancies in symptom resolution time and return-to-play time.

Association of equipment worn and concussion injury rates in National Collegiate Athletic Association football practices: 2004-2005 to 2008-2009 academic years

BACKGROUND

The epidemiology of football-related concussions has been extensively examined. However, although football players experience more at-risk exposure time during practices than competitions, there is a dearth of literature examining the nature of the activities or equipment worn during practice. In particular, varying levels of equipment worn during practices may place players at varying levels of risk for concussion.

PURPOSE

To describe the epidemiology of NCAA men's football concussions that occurred during practices from the 2004-2005 to 2008-2009 academic years by amount of equipment worn.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Men's collegiate football data from the National Collegiate Athletic Association Injury Surveillance System (NCAA ISS) during the 5-year study period were analyzed. Injury rates and injury rate ratios (RRs) were reported with 95% confidence intervals.

RESULTS

During the study period, 795 concussions were reported during practices, resulting in an injury rate of 0.39 per 1000 athlete-exposures (AEs) (95% CI, 0.36-0.42). Among NCAA divisions, Division III had the highest concussion rate (0.54/1000 AEs), followed by Division I (0.34/1000 AEs) and Division II (0.24/1000 AEs) (all P values for RRs comparing divisions<.001). Most concussions in practice occurred when players were fully padded (69.9%), followed by wearing shells (23.5%) and helmets only (1.9%). The practice concussion rate was higher in fully padded practices (0.66/1000 AEs) compared with practices when shells were worn (0.33/1000 AEs; RR=1.99 [95% CI, 1.69-2.35]; P<.001) and practices when only helmets were worn (0.03/1000 AEs; RR=22.39 [95% CI, 13.41-37.39]; P<.001). The practice concussion rate of the preseason (0.76/1000 AEs) was higher than that of the regular season (0.18/1000 AEs; RR=4.14 [95% CI, 3.55-4.83]; P<.001) and that of postseason (0.25/1000 AEs; RR=3.02 [95% CI, 1.95-4.67]; P<.001). The types of practice with the highest concussion rate were scrimmages (1.55/1000 AEs). Although only 3 concussions were sustained during scrimmage practices in which players wore shells, the concussion rate (2.84/1000 AEs) was higher than all other reported rates.

CONCLUSION

Practice concussion rates are highest during fully padded practices, preseason practices, and scrimmages, suggesting that the nature, focus, and intensity of football practices affect concussion risk. In addition, coaching staff should continue to closely monitor player safety during scrimmages. Meanwhile, future surveillance should examine whether removing scrimmages, particularly those that are not fully padded, will meaningfully reduce the incidence and rate of concussions.

Ethics of preparticipation cardiovascular screening for athletes

Preparticipation screening for unsuspected cardiovascular disease is a controversial topic in the medical and lay communities. Much attention has been directed towards young competitive athletes, particularly the proposed strategy of incorporating 12-lead electrocardiograms into the screening process, even on a national or worldwide basis. However, sudden deaths of young athletes owing to genetic or congenital heart diseases have a low incidence in the general population. Furthermore, young people not engaged in competitive sports can harbour the same conditions that cause sudden death in athletes, which has gone largely unrecognized. Notably, sudden deaths from these diseases are numerically far more common in the much larger population of nonathletes. In this Perspectives article, we propose that an ethical dilemma has emerged, raising the important public-health issue of whether young individuals should be arbitrarily excluded from potentially life-saving clinical screening evaluations because they do not engage in competitive sports programmes.