Frequency of head-impact-related outcomes by position in NCAA division I collegiate football players

Pediatric Concussions in Contact Sports: A 10-Year Retrospective Analysis of Mechanisms and Associated Symptoms

Background

Concussions make up a significant proportion of sports injuries. This study aimed to describe the mechanisms of injury and associated symptoms of pediatric patients diagnosed with concussions (age range, 4-17 years) from contact sports.

Hypothesis

Mechanisms of injury would differ based on sex and age, with female athletes and younger athletes aged 4 to 11 years sustaining fewer concussions from player-to-player contact.

Study Design

Descriptive epidemiology study.

Methods

The National Electronic Injury Surveillance System was queried for all contact sport concussions presented to United States emergency departments. The sports analyzed included basketball, football, soccer, hockey, rugby, and lacrosse. Descriptive data, mechanisms of injury, and associated symptoms were analyzed for each sport. Differences in the number of concussions sustained by year and sport, the severity of the injury, and associated symptoms were compared using chi-square test, and differences in proportion were calculated for mechanisms of injury stratified by sex and age.

Results

A total of 12,602 youth athletes sustained concussions between 2012 and 2021. Most patients were male (78.5%), with a mean age of 13.48 years. Football concussions were the most common, with 45.32% of the concussions. The mechanism of injury was largely sport-specific, with player-to-player contact the most common overall. Older male athletes were more likely to have concussions from player-to-player contact, whereas younger athletes were more impacted by head-to-ground mechanisms. Symptom presentation was not sport-specific, and headache and dizziness were the most common presentation at 41.2% and 26.2%, respectively.

Conclusion

The most important overall mechanism of injury was player-to-player contact, especially in older male youth athletes, whereas younger athletes were more likely to be concussed due to head-to-ground injuries.

Position comparison of sport-related concussions in female youth soccer players

OBJECTIVES

Youth soccer participation, particularly among females, continues to grow worldwide. With the high incidence of sport-related concussion (SRC) in soccer, it is important to investigate if SRC occurs disproportionally by positions. Our hypothesis was to see no positional differences in SRCs, SRC-related characteristics, and outcomes among in female youth soccer athletes.

METHODS

Data were prospectively collected from participants at a single sports medicine institution between August 2015-April 2021. Female participants aged 8-18 diagnosed with SRC sustained during an organized soccer practice, scrimmage, or game were separated into 4 groups based on position: Forward, Midfielder, Defender, and Goalkeeper. Demographics, medical history, injury-related details, and outcomes were reviewed. A chi-square test or Fisher's exact test was used for categorical variables. Continuous variables were compared with Mann-Whitney or Kruskal-Wallis test.

RESULTS

Two hundred fourteen participants were included: 52 Forwards, 65 Midfielders, 63 Defenders, and 34 Goalkeepers. There were no significant differences between the groups in age, race, ethnicity, or previous concussion history. Differences in mechanism existed with Goalkeepers most commonly reporting Head to Body Part. Goalkeepers, which make up 1/11 of the total positions on the field, had a significantly higher proportion of SRCs compared to Field Positions. (9.1% vs 15.9%)At 3-month post-enrollment, there were no significant differences in reported symptoms or return-to-play between the different positions.

CONCLUSION

In youth female soccer players, goalkeepers sustained a higher proportion of sport-related concussions compared to field players based upon the composition of a soccer team. The mechanism of injury also differed among the different soccer positions. However, no differences in concussion characteristics, outcomes, or RTP were seen across the different soccer positions.

Analysis of Concussions Reported in American Professional Football Injury Reports in the 2019 Through 2023 Regular Seasons

OBJECTIVE

The National Football League (NFL) has seen increasing scrutiny regarding its management of concussions, especially following an on-field incident involving the Miami Dolphins' quarterback Tua Tagovailoa in the 2022 season. We hope to elucidate the recent trends in the diagnosis and management of concussions during the course of 5 NFL seasons from 2019 to 2023.

METHODS

We queried the NFL injury reports from the 2019 through 2023 database recording players listed with concussions. The weeks missed were calculated using the NFL game logs. Players' concussions that did not occur in the games, those complicated by other injuries, and those affected by roster status were excluded.

RESULTS

Searches of the NFL injury reports resulted in the identification of 664 of 692 concussions (96%) that occurred in regular season games across the 2019-2023 seasons. During the course of these 5 seasons, 31% of the players returned without missing a game, 39% of the players missed 1 game, and 30% of the players missed ≥2 games. No significant difference in the number of concussions per game or weeks missed was observed across the seasons observed. Players with concussions on teams that made the playoffs saw fewer weeks missed than those on non-playoff teams (0.86 vs. 1.37; P = 0.002).

CONCLUSIONS

Since the start of the 2021 NFL season, an increasing incidence of concussions has been noted; however, there was no change observed in the number of weeks missed after the concussions. Trends in the rates of concussions across the seasons remain largely stable, despite increased scrutiny over concussions in the sport.

Cumulative Blast Exposure During a Military Career Negatively Impacts Recovery from Traumatic Brain Injury

Sub-concussive injuries have emerged as an important factor in the long-term brain health of athletes and military personnel. The objective of this study was to explore the relationship between service member and veterans (SMVs) lifetime blast exposure and recovery from a traumatic brain injury (TBI). A total of 558 SMVs with a history of TBI were examined. Lifetime blast exposure (LBE) was based on self-report (M = 79.4, standard deviation = 392.6; range = 0-7500) categorized into three groups: Blast Naive (n = 121), Low LBE (n = 223; LBE range 1-9), and High LBE (n = 214; LBE >10). Dependent variables were the Neurobehavioral Symptom Inventory (NSI) and Post-traumatic Stress Disorder Checklist-Civilian (PCL-C) and the Traumatic Brain Injury Quality of Life (TBI-QOL). Analyses controlled for demographic factors (age, gender, and race) as well as TBI factors (months since index TBI, index TBI severity, and total number lifetime TBIs). The Blast Naive group had significantly lower NSI and PCL-C scores compared with the Low LBE group and High LBE group, with small to medium effect sizes. On the TBI-QOL, the Blast Naïve group had better quality life on 10 of the 14 scales examined. The Low LBE did not differ from the High LBE group on the PCL-C, NSI, or TBI-QOL. Blast exposure over an SMV's career was associated with increased neurobehavioral and post-traumatic stress symptoms following a TBI. The influence of psychological trauma associated with blasts may be an important factor influencing symptoms as well as the accuracy of self-reported estimates of LBE.

Effect of Hearing Status on Concussion Knowledge and Attitudes of Collegiate Athletes

CONTEXT

Collegiate athletes who are deaf or hard-of-hearing (D/HoH) are diagnosed with concussions at a similar rate as athletes who are hearing; however, little evidence exists on knowledge and attitudes of athletes who are D/HoH toward concussions. This study aimed to examine differences in knowledge of and attitudes toward concussions between athletes who are D/HoH and athletes who are hearing.

DESIGN

Cross-sectional research design.

METHODS

Of the 310 athletes who are D/HoH and 430 athletes who are hearing that were invited to participate, 90 athletes who are D/HoH, and 72 athletes who are hearing completed the survey. The Rosenbaum Concussion Knowledge and Attitudes Survey was used to quantify knowledge of and attitude toward concussions. The Rosenbaum Concussion Knowledge and Attitudes Survey consists of the concussion knowledge index (CKI) and the concussion attitudes index (CAI) subscales. Linear regressions were run to test the association of hearing status with CKI and CAI scores. Pearson correlations were performed to determine relationships between CKI and CAI for athletes who are D/HoH and athletes who are hearing. Alpha level was set a priori at P ≤ .05.

RESULTS

Athletes who are hearing demonstrated a higher CKI component score (19.58 [2.19]) compared to athletes who are D/HoH (16.14 [3.31]; P < .001). There were no statistical differences in CAI between hearing groups (hearing: 57.18 [8.73], D/HoH: 55.97 [9.92]; P = .41). There was a moderate positive correlation between CKI and CAI (r = .58) for athletes who are D/HoH, while a weak positive correlation (r = .30) for athletes who are hearing was observed.

CONCLUSIONS

Athletes who are D/HoH have poorer knowledge of concussions but similar attitudes toward concussion as that of athletes who are hearing. Current concussion educational interventions are in written or spoken form which may not be inclusive to athletes who are D/HoH. Health care professionals should consider an athlete's preferred communication mode to improve the efficiency and effectiveness of education.

Blood and MRI biomarkers of mild traumatic brain injury in non-concussed collegiate football players

Football has one of the highest incidence rates of mild traumatic brain injury (mTBI) among contact sports; however, the effects of repeated sub-concussive head impacts on brain structure and function remain under-studied. We assessed the association between biomarkers of mTBI and structural and functional MRI scans over an entire season among non-concussed NCAA Division I linemen and non-linemen. Concentrations of S100B, GFAP, BDNF, NFL, and NSE were assessed in 48 collegiate football players (32 linemen; 16 non-linemen) before the start of pre-season training (pre-camp), at the end of pre-season training (pre-season), and at the end of the competitive season (post-season). Changes in brain structure and function were assessed in a sub-sample of 11 linemen and 6 non-linemen using structural and functional MRI during the execution of Stroop and attention network tasks. S100B, GFAP and BDNF concentrations were increased at post-season compared to pre-camp in linemen. White matter hyperintensities increased in linemen during pre-season camp training compared to pre-camp. This study showed that the effects of repeated head impacts are detectable in the blood of elite level non-concussed collegiate football players exposed to low-moderate impacts to the heads, which correlated with some neurological outcomes without translating to clinically-relevant changes in brain anatomy or function.

The association between playing professional American football and longevity

Recent research concludes that professional American football players (hereafter, "football players") live longer than American men in general, despite experiencing higher rates of chronic traumatic encephalopathy (CTE) and cardiovascular disease (CVD). This suggests that the longevity-enhancing benefits of playing football (e.g., physical fitness, money) outweigh the costs associated with CTE, CVD, and other longevity detriments of playing football. However, these surprising results may be the consequence of flawed research design. To investigate, we conducted two analyses. In analysis 1, we compared a) all professional American football players whose first season was 1986 or between 1988 and 1995 to b) a random sample of same-age American men observed as part of the National Health Interview Surveys in those same years selected on good health, at least 3 y of college, and not being poor. The exposure consists of playing one or more games of professional football; the outcome is risk of death within 25 y. In analysis 2, we use data on 1,365 men drafted to play in the (American) National Football League in the 1950s-906 of whom ultimately played professional football, and 459 of whom never played a game in any professional league. We estimate the association between playing football and survival through early 2023. In both analyses, we investigate differences between linemen and other position players. In contrast to most prior research, in both analyses, we find that linemen died earlier than otherwise similar men; men who played other positions died no earlier (or later).

Interaction of Surface Type, Temperature, and Week of Season on Concussion Risk in the National Football League: A Bayesian Analysis

BACKGROUND

Artificial turf fields and environmental conditions may influence sports concussion risk, but existing research is limited by uncontrolled confounding factors, limited sample size, and the assumption that risk factors are independent of one another. The purpose of this study was to examine how playing surface, time of season, and game temperature relate to diagnosed concussion risk in the National Football League (NFL).

METHODS

This retrospective cohort study examined data from the 2012 to the 2019 NFL regular season. We fit Bayesian negative binomial regression models to relate how playing surface, game temperature, and week of the season independently related to diagnosed concussion risk and any interactions among these factors.

RESULTS

We identified 1096 diagnosed concussions in 1830 games. There was a >99% probability that concussion risk was reduced on grass surface (median incidence rate ratio [IRR] = 0.78 [95% credible interval: 0.68, 0.89]), >99% probability that concussion risk was lower at higher temperatures (IRR = 0.85 [0.76,0.95] for each 7.9 °C), and >91% probability that concussion risk increased with each week of the season (IRR = 1.02 [1.00,1.04]). There was an >84% probability for a surface × temperature interaction (IRR = 1.01 [0.96, 1.28]) and >75% probability for a surface × week interaction (IRR = 1.02 [0.99, 1.05]).

CONCLUSIONS

Diagnosed concussion risk is increased on artificial turf compared with natural grass, and this is exacerbated in cold weather and, independently, later in the season. The complex interplay between these factors necessitates accounting for multiple factors and their interactions when investigating sports injury risk factors and devising mitigation methods.

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

Sport-related concussion prevention strategies in collision sports are a primary interest for sporting organizations and policy makers. After-market soft-shell padding purports to augment the protective capabilities of standard football helmets and to reduce head impact severity. We compared head impact kinematics [peak linear acceleration (PLA) and peak rotational acceleration (PRA)] in athletes wearing Guardian Cap soft-shell padding to teammates without soft-shell padding. Ten Division I college football players were enrolled [soft-shell padding (SHELL) included four defensive linemen and one tight end; non-soft-shell (CONTROL) included two offensive linemen, two defensive linemen, and one tight end]. Participants wore helmets equipped with the Head Impact Telemetry System to quantify PLA (g) and PRA (rad/s2) during 14 practices. Two-way ANOVAs were conducted to compare log-transformed PLA and PRA between groups across helmet location and gameplay characteristics. In total, 968 video-confirmed head impacts between SHELL (n = 421) and CONTROL (n = 547) were analyzed. We observed a Group x Stance interaction for PRA (F1,963 = 7.21; p = 0.007) indicating greater PRA by SHELL during 2-point stance and lower PRA during 3- or 4-point stances compared to CONTROL. There were no between-group main effects. Protective soft-shell padding did not reduce head impact kinematic outcomes among college football athletes.

The Implementation of a Return-to-Play Protocol with Standardized Physical Therapy Referrals in a Collegiate Football Program: PT's Role in Return-to-Play, A Clinical Commentary

Sport-related concussions (SRCs) are multi-faceted injuries requiring coordinated care for return-to-play (RTP). Although the number of concussions in collegiate football is increasing annually, there is poor standardization among RTP protocols. Recent evidence suggests there is an increased risk of lower extremity injury, neuropsychiatric consequences, and re-injury after SRC, and risk factors for a prolonged recovery from SRC have also been identified. Evidence demonstrates a faster RTP and improved outcomes with early physical therapy intervention; however, this is not yet common practice in the treatment of acute SRC. There is little guidance available on the development and implementation of a multidisciplinary RTP rehabilitation protocol for SRC that incorporates standardized physical therapy. By describing an evidence-based RTP protocol with standardized physical therapy management, and measures taken to implement this protocol, this clinical commentary aims to identify steps in treating SRC that can be used to improve recovery. The purpose of this commentary is to: a) survey the current state of standardization of RTP protocols in collegiate football; b) highlight the development and implementation of a RTP protocol with standardized physical therapy referral and management in an NCAA Division II collegiate football program; and c) describe results of a full-season pilot study, including time to evaluation, time to RTP, rate of re-injury or lower extremity injury, and the clinical significance of protocol implementation.

Level of Evidence

Level V.

Transcranial Photobiomodulation Treatment: Significant Improvements in Four Ex-Football Players with Possible Chronic Traumatic Encephalopathy

Background

Chronic traumatic encephalopathy, diagnosed postmortem (hyperphosphorylated tau), is preceded by traumatic encephalopathy syndrome with worsening cognition and behavior/mood disturbances, over years. Transcranial photobiomodulation (tPBM) may promote improvements by increasing ATP in compromised/stressed cells and increasing local blood, lymphatic vessel vasodilation.

Objective

Aim 1: Examine cognition, behavior/mood changes Post-tPBM. Aim 2: MRI changes - resting-state functional-connectivity MRI: salience, central executive, default mode networks (SN, CEN, DMN); magnetic resonance spectroscopy, cingulate cortex.

Methods

Four ex-players with traumatic encephalopathy syndrome/possible chronic traumatic encephalopathy, playing 11- 16 years, received In-office, red/near-infrared tPBM to scalp, 3x/week for 6 weeks. Two had cavum septum pellucidum.

Results

The three younger cases (ages 55, 57, 65) improved 2 SD (p < 0.05) on three to six neuropsychological tests/subtests at 1 week or 1 month Post-tPBM, compared to Pre-Treatment, while the older case (age 74) improved by 1.5 SD on three tests. There was significant improvement at 1 month on post-traumatic stress disorder (PTSD), depression, pain, and sleep. One case discontinued narcotic pain medications and had reduced tinnitus. The possible placebo effect is unknown. At 2 months Post-tPBM, two cases regressed. Then, home tPBM was applied to only cortical nodes, DMN (12 weeks); again, significant improvements were seen. Significant correlations for increased SN functional connectivity (FC) over time, with executive function, attention, PTSD, pain, and sleep; and CEN FC, with verbal learning/memory, depression. Increased n-acetyl-aspartate (NAA) (oxygen consumption, mitochondria) was present in anterior cingulate cortex (ACC), parallel to less pain and PTSD.

Conclusion

After tPBM, these ex-football players improved. Significant correlations of increased SN FC and CEN FC with specific cognitive tests and behavior/mood ratings, plus increased NAA in ACC support beneficial effects from tPBM.

Subtle impairments of perceptual-motor function and well-being are detectable among military cadets and college athletes with self-reported history of concussion

Introduction

A lack of obvious long-term effects of concussion on standard clinical measures of behavioral performance capabilities does not preclude the existence of subtle neural processing impairments that appear to be linked to elevated risk for subsequent concussion occurrence, and which may be associated with greater susceptibility to progressive neurodegenerative processes. The purpose of this observational cohort study was to assess virtual reality motor response variability and survey responses as possible indicators of suboptimal brain function among military cadets and college athletes with self-reported history of concussion (HxC).

Methods

The cohort comprised 75 college students (20.7 ± 2.1 years): 39 Reserve Officer Training Corp (ROTC) military cadets (10 female), 16 football players, and 20 wrestlers; HxC self-reported by 20 (29.2 ± 27.1 months prior, range: 3-96). A virtual reality (VR) test involving 40 lunging/reaching responses to horizontally moving dots (filled/congruent: same direction; open/incongruent: opposite direction) was administered, along with the Sport Fitness and Wellness Index (SFWI) survey. VR Dispersion (standard deviation of 12 T-scores for neck, upper extremity, and lower extremity responses to congruent vs. incongruent stimuli originating from central vs. peripheral locations) and SFWI response patterns were the primary outcomes of interest.

Results

Logistic regression modeling of VR Dispersion (range: 1.5-21.8), SFWI (range: 44-100), and an interaction between them provided 81% HxC classification accuracy (Model χ ²[2] = 26.03, p < .001; Hosmer & Lemeshow χ ²[8] = 1.86, p = .967; Nagelkerke R ²= .427; Area Under Curve = .841, 95% CI: .734, .948). Binary modeling that included VR Dispersion ≥3.2 and SFWI ≤86 demonstrated 75% sensitivity and 86% specificity with both factors positive (Odds Ratio = 17.6, 95% CI: 5.0, 62.1).

Discussion/Conclusion

Detection of subtle indicators of altered brain processes that might otherwise remain unrecognized is clearly important for both short-term and long-term clinical management of concussion. Inconsistency among neck, upper extremity, and lower extremity responses to different types of moving visual stimuli, along with survey responses suggesting suboptimal well-being, merit further investigation as possible clinical indicators of persisting effects of concussion that might prove to be modifiable.

Cerebral and cognitive modifications in retired professional soccer players: TC-FOOT protocol, a transverse analytical study

INTRODUCTION

Soccer is the most popular sport in the world. This contact sport carries the risk of exposure to repeated head impacts in the form of subconcussions, defined as minimal brain injuries following head impact, with no symptom of concussion. While it has been suggested that exposure to repetitive subconcussive events can result in long-term neurophysiological modifications, and the later development of chronic traumatic encephalopathy, the consequences of these repeated impacts remain controversial and largely unexplored in the context of soccer players.

METHODS AND ANALYSIS

This is a prospective, single-centre, exposure/non-exposure, transverse study assessing the MRI and neuropsychological abnormalities in professional retired soccer players exposed to subconcussive impacts, compared with high-level athletes not exposed to head impacts. The primary outcome corresponds to the results of MRI by advanced MRI techniques (diffusion tensor, cerebral perfusion, functional MRI, cerebral volumetry and cortical thickness, spectroscopy, susceptibility imaging). Secondary outcomes are the results of the neuropsychological tests: number of errors and time to complete tests. We hypothesise that repeated subconcussive impacts could lead to morphological lesions and impact on soccer players' cognitive skills in the long term.

ETHICS AND DISSEMINATION

Ethics approval has been obtained and the study was approved by the Comité de Protection des Personnes (CPP) No 2021-A01169-32. Study findings will be disseminated by publication in a high-impact international journal. Results will be presented at national and international imaging meetings.

TRIAL REGISTRATION NUMBER

NCT04903015.

Effects of docosahexaenoic acid and eicosapentaoic acid supplementation on white matter integrity after repetitive sub-concussive head impacts during American football: Exploratory neuroimaging findings from a pilot RCT

Context

Repetitive sub-concussive head impacts (RSHIs) are common in American football and result in changes to the microstructural integrity of white matter. Both docosahexaenoic acid (DHA) and eicosapentaoic acid (EPA) supplementation exerted neuroprotective effects against RSHIs in animal models and in a prior study in football players supplemented with DHA alone.

Objective

Here, we present exploratory neuroimaging outcomes from a randomized controlled trial of DHA + EPA supplementation in American football players. We hypothesized that supplementation would result in less white matter integrity loss on diffusion weighted imaging over the season.

Design setting participants

We conducted a double-blind placebo-controlled trial in 38 American football players between June 2019 and January 2020.

Intervention

Participants were randomized to the treatment (2.442 g/day DHA and 1.020 g/day EPA) or placebo group for five times-per-week supplementation for 7 months. Of these, 27 participants were included in the neuroimaging data analysis (n = 16 placebo; n = 11 DHA + EPA).

Exploratory outcome measures

Changes in white matter integrity were quantified using both voxelwise diffusion kurtosis scalars and deterministic tractography at baseline and end of season. Additional neuroimaging outcomes included changes in regional gray matter volume as well as intra-regional, edge-wise, and network level functional connectivity. Serum neurofilament light (NfL) provided a peripheral biomarker of axonal damage.

Results

No voxel-wise between-group differences were identified on diffusion tensor metrics. Deterministic tractography using quantitative anisotropy (QA) revealed increased structural connectivity in ascending corticostriatal fibers and decreased connectivity in long association and commissural fibers in the DHA+EPA group compared to the placebo group. Serum NfL increases were correlated with increased mean (ρ = 0.47), axial (ρ = 0.44), and radial (ρ = 0.51) diffusivity and decreased QA (ρ = -0.52) in the corpus callosum and bilateral corona radiata irrespective of treatment group. DHA + EPA supplementation did preserve default mode/frontoparietal control network connectivity (g = 0.96, p = 0.024).

Conclusions

These exploratory findings did not provide strong evidence that DHA + EPA prevented or protected against axonal damage as quantified via neuroimaging. Neuroprotective effects on functional connectivity were observed despite white matter damage. Further studies with larger samples are needed to fully establish the relationship between omega-3 supplementation, RSHIs, and neuroimaging biomarkers.

Trial registration

ClinicalTrials.gov-NCT04796207.

Incipient chronic traumatic encephalopathy in active American football players: neuropsychological assessment and brain perfusion measures

Background and aims

Chronic traumatic encephalopathy (CTE) is a degenerative disease caused by repetitive traumatic brain injury (TBI). Because CTE can be definitely diagnosed only post-mortem, it would be important to explore clinical and radiological correlates of CTE and TBI. The aims of this study were to assess (1) the relationship between the neuropsychological profile of active American football players and the traumatic load; (2) whether traumatic brain injury associated with American football activity has a specific cerebral perfusion pattern; and (3) whether this perfusion pattern correlates with neuropsychological performances.

Methods

In 20 American football players [median age [25th–75th percentile] 25.0 [21.6–31.2] years, all males], we evaluated history, traumatic load and symptoms using the TraQ (Trauma Questionnaire), and cognitive performances on neuropsychological tests. Brain perfusion was estimated using arterial spin labeling MRI and compared to a group of 19 male age-matched (28.0 [24.8–32.3] years) healthy subjects.

Results

We found different cognitive performances between American football players stratified according to field position and career length. Linemen had poorer executive, verbal, and visual performances; a career > 7 years was associated with poorer verbal fluency performances. American football players had statistically significant reduced cerebral blood flow values in sensory-motor areas in comparison with healthy controls. Poorer neuropsychological performances correlated with lower perfusion in specific brain areas.

Conclusions

Our study seems to confirm that CTE in American football players is influenced by the field position and the career length, and correlates with lower cognitive performances linked to lower perfusion in specific brain areas.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10072-022-06212-7.

Association Between Head Impact Biomechanics and Physical Load in College Football

Head impacts and physical exertion are ubiquitous in American football, but the relationship between these factors is poorly understood across a competitive season or even within an individual session. Gameplay characteristics, including player position and session type, may contribute to these relationships but have not been prospectively examined. The current study aimed to determine if an association exists between head impact biomechanics and physical load metrics. We prospectively studied college football players during the 2017–2021 football seasons across representative playing positions (15 offensive and defensive linemen, 11 linebackers and tight ends, and 15 defensive backs, running backs, and receivers). Participants wore halters embedded with Catapult Vector GPS monitoring systems to quantify player load and participant helmets were equipped with the Head Impact Telemetry System to quantify head impact biomechanics and repetitive head impact exposure (RHIE). Generalized linear models and linear regression models were employed to analyze in-session and season-long outcomes, while addressing factors such as player position and session type on our data. Player load was associated with RHIE (p < 0.001). Season-long player load predicted season-long RHIE (R² = 0.31; p < 0.001). Position group affected in-session player load (p = 0.025). Both player load and RHIE were greater in games than in practices (p < 0.001), and position group did not affect RHIE (p = 0.343). Physical load burden was associated with RHIE within sessions and across an entire season. Session type affected both RHIE and player load, while position group only affected player load. Our data point to tracking physical load burden as a potential proxy for monitoring anticipated RHIE during the season.

Effects of Fish Oil on Biomarkers of Axonal Injury and Inflammation in American Football Players: A Placebo-Controlled Randomized Controlled Trial

There are limited studies on neuroprotection from repeated subconcussive head impacts (RSHI) following docosahexaenoic acid (DHA) + eicosapentaenoic acid (EPA) supplementation in contact sports athletes. We performed a randomized, placebo-controlled, double-blinded, parallel-group design trial to determine the impact of 26 weeks of DHA+EPA supplementation (n = 12) vs. placebo (high-oleic safflower oil) (n = 17) on serum concentrations of neurofilament light (NfL), a biomarker of axonal injury, and inflammatory cytokines (interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-a)) in National Collegiate Athletic Association Division I American football athletes. DHA+EPA supplementation increased (p < 0.01) plasma DHA and EPA concentrations throughout the treatment period. NfL concentrations increased from baseline to week 26 in both groups (treatment (<0.001); placebo (p < 0.05)), with starting players (vs. non-starters) showing significant higher circulating concentrations at week 26 (p < 0.01). Fish oil (DHA+EPA) supplementation did not mitigate the adverse effects of RSHI, as measured by NfL levels; however, participants with the highest plasma DHA+EPA concentrations tended to have lower NfL levels. DHA+EPA supplementation had no effects on inflammatory cytokine levels at any of the timepoints tested. These findings emphasize the need for effective strategies to protect American football participants from the effects of RSHI.

An update on pathophysiology and treatment of sports-mediated brain injury

Traumatic brain injury (TBI) is a neurological disorder which represents a major health issue worldwide. It causes mortality and disability among all group ages, caused by external force, sports-related events or violence and road traffic accidents. In the USA, approximately one-third people die annually due to injury and 1.7 million people suffer from traumatic brain injury. Every year in India around 1.6 million individuals suffer from sustain brain injury with 200,000 deaths and approximately one million person needed recovery treatment at any stage of time. Sports-related head impact and trauma has become an extremely controversial public health and medico-legal problem that accounts for 20% of all brain injury (including concussion). It is difficult to reverse the primary injury but the secondary injury can be minimized by using proper pharmacological intervention during the initial hours of injury. This article highlights the pathophysiology and types of TBI along with treatment therapies. Till date, there is no single medication that can decrease the progression of the disease so that symptomatic treatment is given to the patient by determining proper pathology. Recently various herbal medicine therapies and traditional supplements have been developed for TBI. Nutritional supplementation and nutraceuticals have exposed potential in the treatment of TBI when used before and after TBI. The compiled data will enable the readers to know the pathophysiology as well as the allopathic and natural remedies to treat the TBI.

Risk of Concussion After a Targeting Foul in Collegiate American Football

Background:

The targeting rule was adopted by the National Collegiate Athletic Association (NCAA) in 2008 to discourage dangerous contact during collegiate American football competition. Although targeting rules have been emphasized as a means to reduce concussion rates, there is currently no evidence that targeting plays are higher risk for concussion than other plays in American football.

Purpose:

To compare the rate of concussion occurring during targeting versus nontargeting plays in American collegiate football.

Study Design:

Cross-sectional study.

Methods:

Concussions occurring in games in the 2016-2019 Pac-12 Conference were classified as having occurred during either (1) a play where a targeting penalty was called or (2) all other plays. Targeting plays were further categorized to either those in which the call was upheld or those overturned by the on-field official after replay review. The number of targeting plays and the total number of plays during games were also recorded. Concussion incidence (per 1000 plays) and risk ratios were calculated.

Results:

Overall, 538 games with 68,670 plays were reviewed, during which 213 concussions occurred (15 during plays where targeting was called and 198 on other plays) and 141 targeting penalties were called. The incidence of concussion was 106.4/1000 plays for targeting plays (including 141.2/1000 upheld targeting fouls and 53.6/1000 overturned targeting fouls) and 2.9/1000 plays for nontargeting plays. The risk of concussion during targeting plays was 36.9 (95% CI, 22.4-60.7) times greater than that for all other plays. The risk of concussion during targeting plays upheld was 49.0 (95% CI, 28.5-84.2) times greater than that for all other plays.

Conclusion:

Concussion risk was significantly higher during plays in which targeting was called, especially those in which targeting fouls were upheld.

Clinical Relevance:

This study supports eliminating or reducing targeting from American football. The results of this study suggest that players should be screened for concussion after targeting plays are called.

Characterizing Head Impact Exposure in Men and Women During Boxing and Mixed Martial Arts

Background:

The accumulation of subconcussive impacts has been implicated in permanent neurological impairment. A gap in understanding the relationship between head impacts and neurological function is the lack of precise characterization and quantification of forces that individuals experience during sports training and competition.

Purpose:

To characterize impact exposure during training and competition among male and female athletes participating in boxing and mixed martial arts (MMA) via an instrumented custom-fit Impact Monitoring Mouthguard (IMM).

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Twenty-three athletes (n = 4 women) were provided a custom-fit IMM. The IMM monitored impacts during sparring and competition. All training and competition sessions were videotaped. Video and IMM data were synchronized for post hoc data verification of true positives and substantiation of impact location. IMM data were collected from boxing and MMA athletes at a collaborating site. For each true-positive impact, peak linear acceleration and peak angular acceleration were calculated. Wilcoxon rank sum tests were used to evaluate potential differences in sport, activity type, and sex with respect to each outcome. Differences in impact location were assessed via Kruskal-Wallis tests.

Results:

IMM data were collected from 53 amateur training sessions and 6 competitions (session range, 5-20 minutes). A total of 896 head impacts (men, n = 786; women, n = 110) were identified using IMM data and video verification: 827 in practice and 69 during competition. MMA and boxers experienced a comparable number of impacts per practice session or competition. In general, MMA impacts produced significantly higher peak angular acceleration than did boxing impacts (P < .001) and were more varied in impact location on the head during competitions. In terms of sex, men experienced a greater number of impacts than women per practice session. However, there was no significant difference between men and women in terms of impact magnitude.

Conclusion:

Characteristic profiles of head impact exposure differed between boxing and MMA athletes; however, the impact magnitudes were not significantly different for male and female athletes.

Targeting Rule Implementation Decreases Concussions in High School Football: A National Concussion Surveillance Study

Background:

Concussions occur at higher rates in high school football as compared with all other high school sports. In 2014, the National Federation of State High School Associations implemented rules defining illegal contact against a defenseless player above the shoulders to reduce concussions in football players in the United States. To the best of our knowledge, rates of emergency department (ED)—diagnosed concussions of high school football players before and after the 2014 rule implementation have not been compared.

Hypothesis:

It was hypothesized that (1) there would be lower rates of helmet-to-helmet and helmet-to-body-part concussions after rule implementation and (2) alternative mechanisms of concussion would not differ, as these would be less influenced by rule implementation.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Data from the National Electronic Injury Surveillance System (NEISS) were analyzed for high school football players 14 to 18 years old sustaining a concussion from January 1, 2009, to December 31, 2019. Data were collected on mechanism of injury, setting, and loss of consciousness. Raw data were used to calculate national estimates based on the assigned statistical sample weight of each hospital by the NEISS.

Results:

A total of 4983 (national estimate = 154,221) high school football concussions were diagnosed in US EDs; 58.8% of concussions occurred during competition and 41.2% during practice. Between 2009 and 2013 the rate of concussions diagnosed in EDs rose 10.7% as compared with a 6.2% decrease between 2015 and 2019 (P = .04). Between 2009 and 2013, the rate of helmet-to-helmet concussions rose 17.6% as compared with a 5.6% decrease between 2015 and 2019 (P = .03). There were no significant changes between other mechanisms of concussion before and after the 2014 rule implementation.

Conclusion:

We identified a decreased trend in overall and helmet-to-helmet high school football concussions diagnosed in the ED after implementation of the targeting rule. This study adds to the growing literature regarding the importance and efficacy of rule implementation in reducing sports-related concussions.

Changes in White Matter of the Cervical Spinal Cord after a Single Season of Collegiate Football

The involvement of the central nervous system (CNS), specifically the white matter tracts in the cervical spinal cord, was examined with diffusion tensor imaging (DTI) following exposure to repetitive head acceleration events (HAEs) after a single season of collegiate football. Fifteen National Collegiate Athletic Association (NCAA) Division 1 football players underwent DTI of the cervical spinal cord (vertebral level C1–4) at pre-season (before any contact practices began) and post-season (within 1 week of the last regular season game) intervals. Helmet accelerometer data were also collected in parallel throughout the season. From pre-season to post-season, a significant decrease (p < 0.05) of axial diffusivity was seen within the right spino-olivary tract. In addition, a significant decrease (p < 0.05) in global white matter fractional anisotropy (FA) along with increases (p < 0.05) in global white matter mean diffusivity (MD) and radial diffusivity (RD) were found. These changes in FA from pre-season to post-season were significantly moderated by previous concussion history (p < 0.05) and number of HAEs over 80 g (p < 0.05). Despite the absence of sports-related concussion (SRC), we present measurable changes in the white matter integrity of the cervical spinal cord suggesting injury from repetitive HAEs, or SRC, may include the entirety of the CNS, not just the brain.

Factors Influencing College Football Players' Beliefs About Incurring Football-Related Dementia

Background:

Football participation is associated with risks to acute and long-term health, including the possibility of incurring football-related dementia. Concerns have been raised regarding media coverage of these risks, which may have influenced athletes’ beliefs. However, little is known about football players’ views on football-related dementia. The risk-perception literature suggests that related risk perceptions and features of individual cognition, such as the ability to switch to reasoned, deliberative thinking, may influence individual perception of a long-term risk.

Purpose:

To evaluate factors influencing college football players’ belief that they are likely to incur football-related dementia in the future.

Study Design:

Cross-sectional study.

Methods:

Members of 4 National Collegiate Athletic Association Division I Power 5 Football teams participated in this survey-based study, providing responses to demographic, athletic, and risk-posture questions, and completed the cognitive reflection test. Logistic regressions were used to evaluate relationships between beliefs about football-related dementia and factors including athletic and demographic characteristics, football risk posture, health-risk posture, and cognitive reflection test score.

Results:

About 10% of the 296 participating athletes thought football-related dementia was likely to occur in their future. Skill players had lower odds than linemen of believing that football-related dementia was likely (odds ratio [OR], 0.35; 95% CI, 0.14-0.89). For each additional suspected concussion in an athlete’s career, his odds of believing football-related dementia was likely increased by 24% (OR, 1.24; 95% CI, 1.07-1.45). Acute and chronic football-related risk perceptions, as well as non–football-related health-risk perceptions, were positively associated with athletes’ belief that football-related dementia was likely. Higher cognitive reflection test scores, a measure of ability to switch to slow, deliberative thinking, was positively associated with odds of believing football-related dementia was likely (OR, 1.57; 95% CI, 1.12-2.21).

Conclusion:

Some athletes view football as generally riskier, while others view football as generally lessri sky. These risk postures are informed by athletes’ concussion history, primary playing position, and ability to switch from fast, reactive thinking to slow, deliberative thinking. Ensuring that athletes are appropriately informed of the risks of participation is an ethical obligation of universities; sports medicine clinicians are appropriate facilitators of conversations about athletes’ health risks.

Are you missing a concussion by watching American football? Video analysis of ball location in a Division 1 football program

OBJECTIVE

Action in a football game occurs quickly. Medical staff can miss a sport-related concussion (SRC) if they do not observe it directly. The objective of this study is to determine if SRCs occur more frequently at ball than away from ball during gameplay. Game-specific concussion statistics can enhance medical provider care of athletes.

METHODS

We used gameplay videos of an NCAA Division I football program to analyze SRCs and determine the primary tackler or ball handler during each concussion play. We compared the relative risk of SRCs for the primary ball handlers/tacklers to that of the other 10 players on the same team during that play.

RESULTS

Over 10 seasons, 26 SRCs occurred at ball for the primary ball handler/tackler position (0.22 SRCs/game) versus 16 away from ball (0.13 SRCs/game). The relative risk of an SRC according to exposure (at ball) vs. no exposure (away from ball) was 16.2 (CI 8.7-30.2, P < .05). Special teams had more SRCs away from ball than at ball, but this was not significant (relative risk 3.32, CI 0.90-12.3, P > .05).

CONCLUSIONS

The study provides medical staff guidance to more efficiently identify in-game SRCs and supports evidence for rules changes.

Association of Position Played and Career Duration and Chronic Traumatic Encephalopathy at Autopsy in Elite Football and Hockey Players

OBJECTIVE

To determine whether an association exists between career duration or position played and the presence of chronic traumatic encephalopathy (CTE) at autopsy in a series of elite football and hockey players.

METHODS

This retrospective cohort study analyzed postmortem brains of 35 former football or hockey players (29 professional, 6 university varsity/major junior), with the presence of CTE at autopsy as the primary outcome. Position played (highest level), age at retirement (indicator of lifetime exposure to sport), and hockey fighting/penalization histories (surrogate marker for role/style of play) were collected. A blinded neuropathologic evaluation of each participant was performed, providing an assessment for neurodegenerative diseases including CTE, based on the 2015 National Institute of Neurological Disorders and Stroke/National Institute of Biomedical Imaging and Bioengineeringconsensus paper.

RESULTS

In total, 17 of 35 former players (48.6%) showed pathologic evidence of CTE. There was no correlation found between position played and CTE presence, nor between hockey fighting/penalization histories and CTE, in either the football or hockey groups (p > 0.75, Mann-Whitney-Wilcoxon). Similarly, there was no association between age at retirement and CTE presence (p > 0.5, Mann-Whitney-Wilcoxon). In 24 of 35 cases (68.6%), other neuropathologies were present, 13 of 24 (54.2%) of which were coexistent with CTE.

CONCLUSION

In this cohort of 35 former collision sports athletes, no significant associations were found between career duration, position or role played, and CTE presence at autopsy. Although limited by the small and nonrepresentative sample studied, these findings suggest that nonsport factors may be important to understand differing susceptibilities among athletes to CTE.

Pluralistic Ignorance as a Contributing Factor to Concussion Underreporting

BACKGROUND

Concussion underreporting is endemic, and social norms are an established predictor of concussion reporting behavior. However, pluralistic ignorance-a situation in which most individuals in a group hold the belief that their peers' views differ from their own, despite views actually being similar-has not been studied in this context.

AIM

To assess whether pluralistic ignorance contributes to concussion underreporting.

METHOD

We surveyed 2,504 military service academy cadets. Each cadet was presented with a survey asking about their willingness to self-report a concussion, their perception of other cadets' willingness to report a concussion, and personal and demographic factors.

RESULTS

Most cadets viewed themselves as more willing to report a concussion than others (mean difference = 1.12, 95% CI [1.02, 1.21]), a belief consistent with pluralistic ignorance. Demographic characteristics were associated with holding this belief. For example, female cadets and upper-class cadets were more likely to show this disparity than male or under-class cadets, respectively. Collegiate athletes not only showed similar willingness to report concussion as nonathletes but also perceived other cadets as less likely to report concussions. Meanwhile, future pilots showed less self-report willingness and perceived that others were similarly unwilling to report concussions.

DISCUSSION

A majority of this economically and geographically diverse population displays characteristics of pluralistic ignorance: They largely share proconcussion reporting sentiments but incorrectly perceive that others do not. This belief is not held uniformly in all subpopulations, which may inform how these beliefs are developed and maintained.

CONCLUSIONS

Pluralistic ignorance is an important consideration in concussion education efforts.

Differences in cervical kinesthesia between amateur athletes with and without a history of contact sport participation

Objective: Identify cervical sensorimotor function differences between amateur athletes with and without a history of contact sport participation. A secondary aim of the study was to explore the association between neck reposition error and previously identified injury risk factors.Design: Cross-sectional.Participants: 27 amateur campus recreation sport athletes with a history of contact sport participation and 20 amateur campus recreation sport athletes with no history of contact sport.Main Outcome Measures: Baseline signs and symptoms (S/S) number and severity, Neck Disability Index, total neck reposition error, maximum reposition error, cervical range of motion, and cervical isometric strength were then compared between independent factor groups (contact vs. non-contact).Results: Amateur sport athletes with a history of contact sport exposure exhibited 25.2% more total neck reposition error and 24.6% more maximum neck reposition error than athletes with no history of contact sport participation. S/S number (r2 = .12, F(2,44) = 6.2, p = .017) and S/S severity (r2 = .14, F(2,44) = 5.6, p = .02) were significantly correlated with total neck reposition error.Conclusions: Athletes with a history of contact sport participation exhibited greater cervical spine reposition error. The degree to which these sensory position-sense deficits increase risk of injury and long-term quality of life is unknown, but should be explored in future studies.

Baseline, retest, and post-injury profiles of auditory neural function in collegiate football players

OBJECTIVES

Recent retrospective studies report differences in auditory neurophysiology between concussed athletes and uninjured controls using the frequency-following response (FFR). Adopting a prospective design in college football players, we compared FFRs before and after a concussion and evaluated test-retest reliability in non-concussed teammates.

DESIGN

Testing took place in a locker room. We analysed the FFR to the fundamental frequency (F0) (FFR-F0) of a speech stimulus, previously identified as a potential concussion biomarker. Baseline FFRs were obtained during the football pre-season. In athletes diagnosed with concussions during the season, FFRs were measured days after injury and compared to pre-season baseline. In uninjured controls, comparisons were made between pre- and post-season.

STUDY SAMPLE

Participants were Tulane University football athletes (n = 65).

RESULTS

In concussed athletes, there was a significant group-level decrease in FFR-F0 from baseline (26% decrease on average). By contrast, the control group's change from baseline was not statistically significant, and comparisons of pre- and post-season had good repeatability (intraclass correlation coefficient = 0.75).

CONCLUSIONS

Results converge with previous work to evince suppressed neural function to the FFR-F0 following concussion. This preliminary study paves the way for larger-scale clinical evaluation of the specificity and reliability of the FFR as a concussion diagnostic.HighlightsThis prospective study reveals suppressed neural responses to sound in concussed athletes compared to baseline.Neural responses to sound show good repeatability in uninjured athletes tested in a locker-room setting.Results support the feasibility of recording frequency-following responses in non-laboratory conditions.

Evaluating the Effect of Concussion Education Programs on Intent to Report Concussion in High School Football

CONTEXT

Concussion underreporting leads to delays in diagnosis and treatment, prolonging recovery time. Athletes' self-report of concussion symptoms therefore reduces risk.

OBJECTIVE

Evaluate the efficacy of three concussion education programs in improving concussion-reporting intention.

DESIGN

Randomized controlled clinical trial with assessment immediately and one-month after education.

SETTING

Three high schools in California.

PATIENTS OR OTHER PARTICIPANTS

118 male football players were randomly assigned to receive concussion education via: CrashCourse (CC), Centers for Disease Control (CDC) video educational materials (Vi), or CDC written educational materials (Wr).

MAIN OUTCOME MEASURES

Concussion-reporting intention was assessed at baseline, immediately after education, and at one-month follow-up. Secondary outcomes included concussion knowledge, attitudes, perceived reporting norms, and perceived behavioral control.

RESULTS

Athletes across all educational formats had significant improvement in concussion-reporting intention immediately following education and at one-month follow-up (mean improvement 6.8% and 11.4%, respectively; p<0.001). Similar findings were observed across all education formats in secondary analyses examining knowledge, attitudes, and perceived behavioral control. However, there were significant differences by education and time (p=0.03). On post-hoc analysis, athletes who received CC had increased concussion-reporting intention immediately and at one-month (baseline=4.7, immediate=6.1, one-month=6.0; p=0.007 compared to significant increases only at one-month for CDC-Vi (baseline=4.3, immediate=5.2, one-month=5.8; p=0.001), and no significant improvement for CDC-Wr (p=0.10). Secondary analyses indicated significant differences between CC and both CDC interventions, in concussion knowledge and attitudes, immediately after education and at one-month. There were no significant differences in perceived behavioral control between-interventions or in perceived concussion-reporting norms across or between interventions.

CONCLUSION

All athletes exhibited improved intent to report concussions, increased concussion knowledge, better concussion attitudes, and more perceived behavioral control, both immediately after education and at one-month follow-up. However, athletes randomized to CC reported greater intent to report concussion, more knowledge, and improved concussion-reporting attitudes, when compared to CDC-Vi and CDC-Wr.

TRIAL REGISTRY

ClinicalTrials.gov trial ID number is XXX.

Predicting Risk of Sport-Related Concussion in Collegiate Athletes and Military Cadets: A Machine Learning Approach Using Baseline Data from the CARE Consortium Study

OBJECTIVE

To develop a predictive model for sport-related concussion in collegiate athletes and military service academy cadets using baseline data collecting during the pre-participation examination.

METHODS

Baseline assessments were performed in 15,682 participants from 21 US academic institutions and military service academies participating in the CARE Consortium Study during the 2015-2016 academic year. Participants were monitored for sport-related concussion during the subsequent season. 176 baseline covariates mapped to 957 binary features were used as input into a support vector machine model with the goal of learning to stratify participants according to their risk for sport-related concussion. Performance was evaluated in terms of area under the receiver operating characteristic curve (AUROC) on a held-out test set. Model inputs significantly associated with either increased or decreased risk were identified.

RESULTS

595 participants (3.79%) sustained a concussion during the study period. The predictive model achieved an AUROC of 0.73 (95% confidence interval 0.70-0.76), with variable performance across sports. Features with significant positive and negative associations with subsequent sport-related concussion were identified.

CONCLUSION(S)

This predictive model using only baseline data identified athletes and cadets who would go on to sustain sport-related concussion with comparable accuracy to many existing concussion assessment tools for identifying concussion. Furthermore, this study provides insight into potential concussion risk and protective factors.

Effect of subconcussive impacts on functional outcomes over a single collegiate football season

Context

In collision sports, particularly American football, athletes can accumulate thousands of subconcussive impacts, or head acceleration events (HAEs), across a single season; however, the short-term consequences of these impacts are not well understood.

Objective

To investigate the effects of the accumulation of impacts during practices on cognitive functions over a single football season.

Design

Prospective observational study.

Setting

Athletic training room and University laboratory.

Participants

Twenty-three NCAA Football Bowl Subdivision players.

Main outcome measures

Helmet accelerometers during practices and virtual reality testing (VR; balance, reaction time, spatial memory) before and after the season.

Results

Preseason had the majority of ≥80 G impacts while during the season had the majority of ≥25 G to <80 G impacts and positional differences showed that linemen had the majority of both types. Virtual reality analysis revealed that scores significantly decreased after the season for spatial navigation ( p < 0.05) but not for balance or reaction time. Significant correlations ( p < 0.05) were found between cognitive measures and player demographic variables.

Conclusions

Even in the absence of clinical symptoms and concussion diagnosis, repetitive impacts may cause cognitive alterations. Documenting the distribution of impact quantity and intensity as a function of time and position may be considered by coaches and clinicians to reduce the accumulation of impacts in athletes exposed in contact sports.

Accuracy of US College Football Players' Estimates of Their Risk of Concussion or Injury

IMPORTANCE

Despite increased concern about the health consequences of contact sports, little is known about athletes' understanding of their own risk of sports-related injury.

OBJECTIVE

To assess whether college football players accurately estimate their risk of concussion and nonconcussion injury and to identify characteristics of athletes who misestimate their injury risk.

DESIGN, SETTING, AND PARTICIPANTS

In this survey study, questionnaires were given to 296 current college football players on 4 teams from the 3 of the 5 most competitive conferences of the US National Collegiate Athletic Association. Surveys were conducted between February and May 2017. Data were analyzed from June 2017 through July 2020.

MAIN OUTCOMES AND MEASURES

Multiple approaches were taken to compare athlete perceptions of their risks of concussion and nonconcussion injury with individual probabilities of these risks, which were modeled using logistic regression.

RESULTS

Of 296 male college-aged athletes from 4 football teams who participated in the survey, 265 (89%) answered all questions relevant for this study. Participating teams were similar to nonparticipating teams across nearly all measured characteristics. One hundred athletes (34%) had sustained 1 or more concussions, and 197 (68% of the 289 who responded to the question) had sustained 1 or more injuries in the previous football season. Logistic regression models of single-season injury and concussion had reasonably good fit (area under the curve, 0.75 and 0.73, respectively). Of the 265 participants for whom all relevant data were available, 111 (42%) underestimated their risk of concussion (χ2 = 98.6; P = .003). A similar proportion of athletes (113 [43%]) underestimated their risk of injury, although this was not statistically significant (χ2 = 34.0; P = .09). An alternative analytic strategy suggested that 241 athletes (91%) underestimated their risk of injury (Wilcoxon statistic, 7865; P < .001) and 167 (63%) underestimated their risk of concussion (Wilcoxon statistic, 26 768; P < .001).

CONCLUSIONS AND RELEVANCE

The findings of this survey study suggest that college football players may underestimate their risk of injury and concussion. The implications for informed participation in sport are unclear given that people generally underestimate health risks. It is necessary to consider whether athletes are sufficiently informed and how much risk is acceptable for an athlete to participate in a sport.

A Review of On-Field Investigations into the Biomechanics of Concussion in Football and Translation to Head Injury Mitigation Strategies

This review paper summarizes the scientific advancements in the field of concussion biomechanics in American football throughout the past five decades. The focus is on-field biomechanical data collection, and the translation of that data to injury metrics and helmet evaluation. On-field data has been collected with video analysis for laboratory reconstructions or wearable head impact sensors. Concussion biomechanics have been studied across all levels of play, from youth to professional, which has allowed for comparison of head impact exposure and injury tolerance between different age groups. In general, head impact exposure and injury tolerance increase with increasing age. Average values for concussive head impact kinematics are lower for youth players in both linear and rotational acceleration. Head impact data from concussive and non-concussive events have been used to develop injury metrics and risk functions for use in protective equipment evaluation. These risk functions have been used to evaluate helmet performance for each level of play, showing substantial differences in the ability of different helmet models to reduce concussion risk. New advances in head impact sensor technology allow for biomechanical measurements in helmeted and non-helmeted sports for a more complete understanding of concussion tolerance in different demographics. These sensors along with advances in finite element modeling will lead to a better understanding of the mechanisms of injury and human tolerance to head impact.

Head acceleration event metrics in youth contact sports more dependent on sport than level of play

The goal of the study was to evaluate how repetitive head traumas sustained by athletes in contact sports depend on sport and level of play. A total of 16 middle school football players, 107 high school football players, and 65 high school female soccer players participated. Players were separated into levels of play: middle school (MS), freshman (FR), junior varsity (JV), junior varsity-varsity (JV-V), and varsity (V). xPatch sensors were used to measure peak translational and angular accelerations (PTA and PAA, respectively) for each head acceleration event (HAE) during practice and game sessions. Data were analyzed using a custom MATLAB program to compare metrics that have been correlated with functional neurological changes: session metrics (median HAEs per contact session), season metrics (total HAEs, cumulative PTA/PAA), and regressions (cumulative PTA/PAA versus total HAEs, total HAEs versus median HAEs per contact session). Football players had greater session (p<.001) and season (p<.001) metrics than soccer players, but soccer players had a significantly greater player average PAA per HAE than football players (p<.001). Middle school football players had similar session and season metrics to high school level athletes. In conclusion, sport has a greater influence on HAE characteristics than level of play.

Youth American football quarterback injuries: a descriptive study of 15 years of retrospective data

Objectives: To describe common injuries of youth American football quarterbacks (QBs) cared for in a regional sports medicine center within the last 15 years. Methods: A retrospective chart review of all male youth American football QB patients who sustained sports-related injuries at a regional pediatric medical center between 01/01/2003 and 10/01/2018. Patients were identified using HoundDog to search the term 'quarterback.' Records were then reviewed to identify all male QBs ≤ 18 years of age. Injures that were not a result of football participation were excluded. Main outcome variables were injured anatomic locations, injury types, surgical status, and settings in which the injury was sustained. Descriptive statistics were used to analyze the outcome variables. Results: A total of 374 QBs (mean age: 14.6 ± 2.1) sustained a total of 423 injuries. The top 5 injured anatomic locations were shoulder (22%), knee (15%) head/neck (14%), elbow (13%), and wrist/hand/lower arm (11%). Most injuries (64.3%) were acute; 35.7% were chronic in nature. Most acute injuries (55.5%) occurred during games. Of the chronic injuries, 47.0% occurred during off-season and 34.4% occurred in-season. Among all injuries, 22.9% were surgical cases, and the top 3 anatomic locations of surgery were knee (35.0%), shoulder (20.7%), and elbow (18.7%). Conclusions: The shoulder is the most commonly injured body part among young QBs seeking care in a regional pediatric medical center, although the knee is the most commonly injured body part that requires surgery. Most QB injuries are acute in mechanism and the majority of these acute injuries occur during games.

Analysis of Football Injuries by Position Group in Division I College Football: A 5-Year Program Review

OBJECTIVE

The purpose of this study was to evaluate injury characteristics by position groups.

DESIGN

Prospective, observational study.

SETTING

A single, major Division I collegiate football program.

PARTICIPANTS

All players on a collegiate football program each fall regular season.

INDEPENDENT VARIABLES

Exposure to Division I collegiate football and position groups.

MAIN OUTCOME MEASURES

Injury rates (IRs) per 1000 athlete exposures (AEs) and injury rate ratios (IRRs) were calculated and analyzed for all monitored injury variables, which included time in the season, body part, type of injury, game and practice injuries, mechanism of injury, and type of exposure.

RESULTS

During the 2012 to 2016 fall regular seasons, there were 200 reported injuries sustained from 48 615 AE. The overall 5-year IR was 4.11 per 1000 AEs (3.57-4.72 95% confidence intervals). Skill players sustained the highest IR in the preseason (IR, 7.56) compared with line (IR, 4.26) and other (IR, 4.10) position groups. In addition, skill players demonstrated a significantly higher IRR compared with the line (IRR, 1.75, P < 0.05) and other (IRR, 1.85, P < 0.05) position groups.

CONCLUSIONS

Skill players sustained most of their injuries in the preseason, whereas the linemen and other position groups suffered most of their injuries in the first half of the regular season. Skill players demonstrated a significantly higher IR in preseason, noncontact mechanism injuries, and injuries to the upper leg and thigh compared with line and other position groups. Efforts to reduce soft-tissue muscle strains in skill players targeting the preseason may provide one of the best opportunities to significantly decrease current football IRs, whereas efforts to reduce contact exposures may have the greatest effect on concussions and contact mechanism injuries for the other position group. There were no significant differences in IRs between position groups and type of exposure.

Mitigating the Consequences of Subconcussive Head Injuries

Subconcussive head injury represents a pathophysiology that spans the expertise of both clinical neurology and biomechanical engineering. From both viewpoints, the terms injury and damage, presented without qualifiers, are synonymously taken to mean a tissue alteration that may be recoverable. For clinicians, concussion is evolving from a purely clinical diagnosis to one that requires objective measurement, to be achieved by biomedical engineers. Subconcussive injury is defined as subclinical pathophysiology in which underlying cellular- or tissue-level damage (here, to the brain) is not severe enough to present readily observable symptoms. Our concern is not whether an individual has a (clinically diagnosed) concussion, but rather, how much accumulative damage an individual can tolerate before they will experience long-term deficit(s) in neurological health. This concern leads us to look for the history of damage-inducing events, while evaluating multiple approaches for avoiding injury through reduction or prevention of the associated mechanically induced damage.

Concussion History and Career Status Influence Performance on Baseline Assessments in Elite Football Players

OBJECTIVE

To determine if concussion history and career status is associated with neurocognitive performance in elite football players.

METHODS

The study design was a cross-sectional single assessment. Fifty-seven elite football players (age 29.39 ± 7.49 years) categorized as draft prospects, active professional players, and retired professional players were assessed on the Sport Concussion Assessment Tool - third edition (SCAT-3), in an outpatient therapy setting.

RESULTS

Common symptoms were the following: fatigue (45.6%), trouble falling asleep (35.1%), difficulty remembering (33.3%) and irritability (22.8%); 36.8% reported no symptoms. The low concussion (0-1) group reported fewer symptoms (U = 608.50, p < .001), less symptom severity (U = 598.00, p = -.001), and produced greater scores on the Standardized Assessment of Concussion (SAC) total scores compared to the multiple concussion (2+) group (U = 253.00, p = .024), but no differences were observed on modified Balance Error Scoring System (m-BESS) scores (U = 501.50, p = .066) on the Mann-Whitney U test. The Kruskal-Wallis test and post-hoc analysis indicated retired players were significantly different from draft prospects and current professional players for total symptom scores (p < .001), total symptom severity (p < .001), SAC total scores (p = .030), and m-BESS (p < .001).

CONCLUSIONS

Concussion history and career status appear associated with total symptoms, symptom severity, performance on the SAC, and the m-BESS in elite football players. With this in mind, future research is recommended to determine longitudinal impact for elite football players.

Duration of American Football Play and Chronic Traumatic Encephalopathy

OBJECTIVE

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with exposure to contact and collision sports, including American football. We hypothesized a dose-response relationship between duration of football played and CTE risk and severity.

METHODS

In a convenience sample of 266 deceased American football players from the Veterans Affairs-Boston University-Concussion Legacy Foundation and Framingham Heart Study Brain Banks, we estimated the association of years of football played with CTE pathological status and severity. We evaluated the ability of years played to classify CTE status using receiver operating characteristic curve analysis. Simulation analyses quantified conditions that might lead to selection bias.

RESULTS

In total, 223 of 266 participants met neuropathological diagnostic criteria for CTE. More years of football played were associated with having CTE (odds ratio [OR] = 1.30 per year played, 95% confidence interval [CI] = 1.19-1.41; p = 3.8 × 10-9 ) and with CTE severity (severe vs mild; OR = 1.14 per year played, 95% CI = 1.07-1.22; p = 3.1 × 10-4 ). Participants with CTE were 1/10th as likely to have played <4.5 years (negative likelihood ratio [LR] = 0.102, 95% CI = 0.100-0.105) and were 10 times as likely to have played >14.5 years (positive LR = 10.2, 95% CI = 9.8-10.7) compared with participants without CTE. Sensitivity and specificity were maximized at 11 years played. Simulation demonstrated that years played remained adversely associated with CTE status when years played and CTE status were both related to brain bank selection across widely ranging scenarios.

INTERPRETATION

The odds of CTE double every 2.6 years of football played. After accounting for brain bank selection, the magnitude of the relationship between years played and CTE status remained consistent. ANN NEUROL 2020;87:116-131.

Multiple Concussions Increase Odds and Rate of Lower Extremity Injury in National Collegiate Athletic Association Athletes After Return to Play

BACKGROUND

Concussion in collegiate athletics is one of the most prevalent sport-related injuries in the United States, with recent studies suggesting persistent deficits in neuromuscular control after a concussion and an associated increase in risk of lower extremity injury.

PURPOSE

To expand on the relationship between concussion and lower extremity injury by examining the effect of multiple concussions (MC) on rate and odds of future lower extremity injury in collegiate athletes after return to play (RTP) compared with matched controls.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

From 2001 to 2016, 48 National Collegiate Athletic Association Division I athletes sustaining multiple concussions at a single institution were identified. Athletes with multiple concussions (MC) were matched directly to athletes with a single concussion (SC) and to athletes with no concussion history (NC) by sex, sport, position, and games played. Incidence of, time to, and location of lower extremity injury were recorded for each group after RTP from their first reported concussion until completion of their collegiate career. Logistic regression was used to analyze odds ratios (ORs) for sustaining lower extremity injury, whereas time to injury was summarized by use of Kaplan-Meier curves and log rank test analysis.

RESULTS

The incidence of lower extremity injury after RTP was significantly greater (P = .049) in the MC cohort (36/48, 75%) than in SC athletes (25/48 = 52%) and NC athletes (27/48 = 56%). Similarly, odds of lower extremity injury were significantly greater in the MC cohort than in SC athletes (OR, 3.00; 95% CI, 1.26-7.12; P = .01) and NC athletes (OR, 1.66; 95% CI, 1.07-2.56; P = .02). Time to lower extremity injury was significantly shorter in the MC group compared with matched controls (P = .01). No difference was found in odds of lower extremity injury or time to lower extremity injury between SC and NC athletes.

CONCLUSION

Collegiate athletes with MC were more likely to sustain a lower extremity injury after RTP in a shorter time frame than were the matched SC and NC athletes. This may suggest the presence of a cohort more susceptible to neuromuscular deficits after concussion or more injury prone due to player behavior, and it may imply the need for more stringent RTP protocols for athletes experiencing MC.

Traumatic brain injury (TBI) in collision sports: Possible mechanisms of transformation into chronic traumatic encephalopathy (CTE)

Traumatic brain injury (TBI) is a leading cause of death and disability, contributing to ~30% of all injury-related deaths in the US. TBI occurs when a force transmitted to the head causes neuropathologic damage and impairment of brain function. TBI doubles risk of suicide and is the major determinant of acquired seizure disorders. TBI arising from closed head trauma (CHT) significantly increases the risk of developing Alzheimer's disease (AD), Parkinson's disease (PD) and chronic traumatic encephalopathy (CTE). Evidence for a possible role of TBI as a risk factor for sporadic amyotrophic lateral sclerosis (sALS) has been provided by studies of professional players of European football. Depending on age, genetic make-up (in particular, being a carrier of one or two ApoE4 alleles), the number of TBIs sustained, their severity, the time periods involved, and many other factors that affect vulnerability, decades may pass after occurrence of one or more TBIs before sequelae such as AD, PD, sALS or CTE become clinically evident. Among college and professional football players who experience repeated concussions and sub-concussive blows to the head, the risk of developing CTE increases with the number of years actively devoted to the sport, and the degree of exposure to physical impacts inherent in the position played. Following a moderate or severe concussion, or a series of mild blows to the head, the brain may undergo subtle pathophysiological changes that are unlikely to be detected with confidence using available diagnostic methods. Biomarkers are being sought that can help the attending physician infer the likely presence of an ongoing occult neurodegenerative process. One example of the adverse effect of collision on the brain is "heading" the soccer ball-a feat that, repeated over years of competition, has been found to produce severe brain damage in veteran players. CTE has attracted increasing national attention because of its devastating effects in a high proportion of retired professional players of American football. In a study of brains from deceased former football players, contributed mostly by family members, CTE was neuropathologically diagnosed in 110 of 111 of National Football League (NFL) veterans. In the CTE-positive subjects, the authors observed extensive brain atrophy, astrogliosis, myelinated axonopathy, microvascular injury, perivascular neuroinflammation, and phosphorylated tau protein pathology. CTE's neuropathology has been formally defined as a tauopathy characterized by a distinct perivascular accumulation of hyperphosphorylated tau in neurons and astrocytes within cerebral sulci. Although the mechanism that underlies the unforeseen emergence of CTE long after the occurrence of one or more closed head traumas is unknown, an explanation proposed by Albayram and associates is persuasive. They discovered TBI-induced neuronal production of the toxic compound cis P-tau, an abnormal and destructive isomer of the normal and benign trans P-tau, in mouse models of CTE. Cis P-tau produced a CTE-like syndrome via a process they termed cistauosis. Cistauosis can be blocked in laboratory animals by cis P-tau monoclonal antibody, which prevents later development of tau tangles, brain atrophy and virtual CTE. In a subsequent study, the same group found in human samples obtained post-TBI from a variety of causes, that cis P-tau is induced in cortical axons and cerebrospinal fluid and positively correlates with axonal injury and clinical outcome. Thus, cis P-tau appears to contribute to short-term and long-term sequelae after TBI, but may be subject to neutralization by cis-antibody treatment.

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.

Development and Multi-Scale Validation of a Finite Element Football Helmet Model

Head injury is a growing concern within contact sports, including American football. Computational tools such as finite element (FE) models provide an avenue for researchers to study, and potentially optimize safety tools, such as helmets. The goal of this study was to develop an accurate representative helmet model that could be used in further study of head injury to mitigate the toll of concussions in contact sports. An FE model of a Schutt Air XP Pro football helmet was developed through three major steps: geometry development, material characterization, and model validation. The fully assembled helmet model was fit onto a Hybrid III dummy head–neck model and National Operating Committee on Standards for Athletic Equipment (NOCSAE) head model and validated through a series of 67 representative impacts similar to those experienced by a football player. The kinematic and kinetic response of the model was compared to the response of the physical experiments, which included force, head linear acceleration, head angular velocity, and carriage acceleration. The outputs between the model and the physical tests were quantitatively evaluated using CORelation and Analysis (CORA), amounting to an overall averaged score of 0.76. The model described in this study has been extensively validated and can function as a building block for innovation in player safety.

Repetitive Head Impact Exposure in College Football Following an NCAA Rule Change to Eliminate Two-A-Day Preseason Practices: A Study from the NCAA-DoD CARE Consortium

Repetitive head impact exposure sustained by athletes of contact sports has been hypothesized to be a mechanism for concussion and a possible explanation for the high degree of variability in sport-related concussion biomechanics. In an attempt to limit repetitive head impact exposure during the football preseason, the NCAA eliminated two-a-day practices in 2017, while maintaining the total number of team practice sessions. The objective of this study was to quantify head impact exposure during the preseason and regular season in Division I college football athletes to determine whether the 2017 NCAA ruling decreased head impact exposure. 342 unique athletes from five NCAA Division I Football Bowl Subdivision (FBS) programs were consented and enrolled. Head impacts were recorded using the Head Impact Telemetry (HIT) System during the entire fall preseasons and regular seasons in 2016 and 2017. Despite the elimination of two-a-day practices, the number of preseason contact days increased in 2017, with an increase in average hourly impact exposure (i.e., contact intensity), resulting in a significant increase in total head impact burden (+ 26%) for the 2017 preseason. This finding would indicate that the 2017 NCAA ruling was not effective at reducing the head impact burden during the football preseason. Additionally, athletes sustained a significantly higher number of recorded head impacts per week (+ 40%) during the preseason than the regular season, implicating the preseason as a time of elevated repetitive head impact burden. With increased recognition of a possible association between repetitive head impact exposure and concussion, increased preseason exposure may predispose certain athletes to a higher risk of concussion during the preseason and regular season. Accordingly, efforts at reducing concussion incidence in contact sports should include a reduction in overall head impact exposure.

A Mechanical Brain Damage Framework Used to Model Abnormal Brain Tau Protein Accumulations of National Football League Players

A mechanics-based brain damage framework is used to model the abnormal accumulation of hyperphosphorylated p-tau associated with chronic traumatic encephalopathy within the brains of deceased National Football League (NFL) players studied at Boston University and to provide a framework for understanding the damage mechanisms. p-tau damage is formulated as the multiplicative decomposition of three independently evolving damage internal state variables (ISVs): nucleation related to number density, growth related to the average area, and coalescence related to the nearest neighbor distance. The ISVs evolve under different rates for three well known mechanical boundary conditions, which in themselves introduce three different rates making a total of nine scenarios, that we postulate are related to brain damage progression: (1) monotonic overloads, (2) cyclic fatigue which corresponds to repetitive impacts, and (3) creep which is correlated to damage accumulation over time. Different NFL player positions are described to capture the different types of damage progression. Skill position players, such as quarterbacks, are expected to exhibit a greater p-tau protein accumulation during low cycle fatigue (higher amplitude impacts with a lesser number), and linemen who exhibit a greater p-tau protein accumulation during high cycle fatigue (lower amplitude impacts with a greater number of impacts). This mechanics-based damage framework presents a foundation for developing a multiscale model for traumatic brain injury that combines mechanics with biology.

A semi-quantitative sport-specific assessment of recurrent traumatic brain injury: the TraQ questionnaire and its application in American football

Chronic traumatic encephalopathy (CTE) is very frequent and studied among contact sport players, above all American Football. Now, the defined diagnosis is only post-mortem and, consequently, more detailed diagnostic in-vivo instruments are needed to facilitate diagnosis and to allow a follow up. This clinical questionnaire (Trauma Questionnaire-TraQ) has been designed to investigate in parallel the traumatic load and clinical and cognitive subjective symptoms. It evaluates 4 anamnestic fields (specific sport activity, all previous pathological events, clinical manifestations compatible with TBI (traumatic brain injury) or CTE and subjective perception of personal memory efficacy with PRMQ questionnaire). The aim of TraQ questionnaire is to allow a standardized follow-up of active players and to identify subclinical disturbances that may become warnings. A pilot comparative study with TraQ on 105 subjects (75 AF players and 30 comparable people without a history of contact-sports activity) revealed that AF players have an increased amount of severe head trauma, an amplified level of subjective aggressiveness, more olfactory deficits but also more speech subjective problems, previously never related with CTE. In view of the obtained results, the TraQ seems to be useful (1) to obtain a better quantification of the traumatic load; (2) to differentiate the risk of long-term neurological consequences, allowing better management of different athletes right from the pre-symptomatic phases; (3) to manage prevention strategies if regularly applied to periodic visits to sports fitness; and (4) to identify the predisposing factors for the development of CTE and other neurological consequences of TBI with follow-up studies.