High School American Football Research Articles

Arthroscopic Shoulder Stabilization in High School Football Players.

Destabilizing shoulder injuries are common in high school American football players; however, the rate of recurrent glenohumeral instability and return to play after arthroscopic labral stabilization surgery remains unknown. The purpose of this study was to determine the rate of recurrent instability on return to competitive high school football after arthroscopic shoulder labral stabilization and capsulorrhaphy procedures. It was hypothesized that the instability rate would be greater in players with more years of eligibility remaining (YER) to play at the high school level. Case series; Level of evidence, 4. Consecutive male high school football players with at least 1 YER who sustained at least 1 anterior traumatic inseason shoulder instability episode and underwent arthroscopic stabilization between 2012 and 2017 were identified. Patients and/or families were contacted by phone to discuss (1) recurrent instability episodes and (2) return to competitive sport and/or recreational athletic activity. Statistical analysis was conducted using chi-square tests to compare recurrent shoulder instability with return to play and YER. A total of 45 football players aged 14 to 17 years were included, with a mean follow-up of 4.1 years. Most patients (60%) chose not to return to competitive football, due mainly to fear of recurrent injury. Overall, the recurrent instability rate was 15.6% (7/45). The instability rate in players who returned to football was 16.7%, with 66.7% requiring revision surgery. The instability rate in patients who did not return to football was 14.8%, with no revision procedures required. In players who returned to football, the instability rate in YER group 4 was significantly higher than that in YER groups 1 to 3 (42% vs 10.5%, respectively, P = .03), with each year of play conferring an additional 10% risk of reinjury. There was a significant difference in the type of recurrent instability in players who returned to any sport versus those who did not (P = .029). High school football players who returned to competitive play after arthroscopic shoulder stabilization surgery experienced a higher rate of recurrent instability that was dependent on their YER. Over half of the players chose not to return to football, with fear of reinjury being the most common reason.

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 impactsinitiated 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 worehelmets 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 maycontribute to head injury risk.

Longitudinal changes in resting state fMRI brain self-similarity of asymptomatic high school American football athletes

American football has become the focus of numerous studies highlighting a growing concern that cumulative exposure to repetitive, sports-related head acceleration events (HAEs) may have negative consequences for brain health, even in the absence of a diagnosed concussion. In this longitudinal study, brain functional connectivity was analyzed in a cohort of high school American football athletes over a single play season and compared against participants in non-collision high school sports. Football athletes underwent four resting-state functional magnetic resonance imaging sessions: once before (pre-season), twice during (in-season), and once 34–80 days after the contact activities play season ended (post-season). For each imaging session, functional connectomes (FCs) were computed for each athlete and compared across sessions using a metric reflecting the (self) similarity between two FCs. HAEs were monitored during all practices and games throughout the season using head-mounted sensors. Relative to the pre-season scan session, football athletes exhibited decreased FC self-similarity at the later in-season session, with apparent recovery of self-similarity by the time of the post-season session. In addition, both within and post-season self-similarity was correlated with cumulative exposure to head acceleration events. These results suggest that repetitive exposure to HAEs produces alterations in functional brain connectivity and highlight the necessity of collision-free recovery periods for football athletes.

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

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. 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. 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]. 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.

At-Risk Tackling Techniques and Effectiveness in NCAA Division I Collegiate Football.

Head-down tackling has been associated with injuries to the brachial plexus, cervical spine, and head in high school and collegiate American football. Head-down tackling has also been associated with decreased effectiveness in successful tackles compared with head-up tackling. To assess tackling techniques used during National Collegiate Athletic Association (NCAA) Division I football games and to evaluate the successful tackling rates according to technique. Cross-sectional study. Three reviewers analyzed 1000 consecutive solo defensive tackling attempts made in the 2021 season (October to December) by 8 universities within the NCAA Southeastern Conference. Slow-motion replays were used to analyze the success of the tackling attempt, the tackling method, and the initial point of contact with respect to the offensive player's waist. The chi-square or Fisher exact test was used to analyze categorical data, and the 2-tailed Student t-test or the Mann-Whitney U test was used to analyze continuous data. Head-up and head-down tackling occurred in 902 (90.2%) and 98 (9.8%) tackle attempts, respectively. Head-up tackles were successful in 76.2% of the attempts compared with 55.1% for head-down tackles (P < .001). Tackles were made at or above the offensive player's waist in 777 (77.7%) attempts and below the waist in 223 (22.3%) attempts. Tackles at or above the waist were successful in 77.6% of the attempts compared with 61.9% of tackles below the waist (P < .001). The inside-shoulder method was used in 592 (59.2%) tackles, the arm method in 317 (31.7%), the head-across-the-bow method in 72 (7.2%), and the helmet-to-helmet method in 19 (1.9%). Inside-shoulder tackles had the highest success rate of 93.2%, compared with 41.6% for arm (P < .001), 59.7% for head-across-the-bow (P < .001), and 73.7% for helmet-to-helmet (P = .001) tackles. Inside-shoulder tackles resulted in head-up tackling in 92.9% compared with 41.7% for head-across-the-bow (P < .001) and 57.9% for helmet-to-helmet (P < .001) tackles. There were no recorded injuries to the tackler. Head-up tackles, tackles made at or above the offensive player's waist, and inside-shoulder tackles had the highest success rates. Head-down tackling and tackling below the waist were associated with poor tackling methods, including head-across-the-bow and helmet-to-helmet tackles, which had lower success rates.

Evaluation of the Back-in-Action test Battery In Uninjured High School American Football Players.

Return to sport testing is an established routine, especially for athletes who have ruptured their anterior cruciate ligament (ACL). Various tests are performed, often combined in test batteries, such as the Back-in-action (BIA) test battery. Unfortunately, pre-injury performance is often unknown, and only few athletes pass the high demands of these test batteries. The aim of the study was to determine the performance of under 18 American football players on the BIA to establish pre-injury sport specific benchmarks for future RTS testing and to compare these values to data from an age-matched reference group. Fifty-three healthy male American football players underwent a functional assessment using the "Back-in-action" test battery evaluating agility, speed (Parkour-Jumps and Quick-Feet test), balance (using a PC based balance board), and power (Counter-Movement-Jump [CMJ]) as objective measures. Their results were compared with a previously tested reference group (RP) and within the american football players (AF) through three subgroups according to field playing position. Overall, the American football (AF) athletes showed lower balance scores for both legs (AF: 3.71/3.57/3.61; RP: 3.4/3.2/3.2; p<0.002) compared to the reference population (RP). CMJ height and Quick-Feet results were not statistically different (p>0.05), Parkour-Jump times (AF: 8.18/ 8.13 sec.; RP: 5.9/5.9sec.; p<0.001) were significantly slower. Power output in all CMJ's (AF: 46.86/36.94/37.36 W/kg; RP: 43.2/29.5/29 W/kg; p<0.001) was significantly higher than the RP. Passing and running game involved players (G2 & G3) showed significantly better balance scores (G2+G3: 3.36/3.27/3.33; G1: 4.22/4.06/4.10; p<0.001), higher jump height (G2&G3: 38.87/24.02/24.96 cm; G1: 32.03/19.50/18.96 cm; p<0.001) and more watts/kg (G2&G3: 48.83/37.21/37.64 W/kg; G1: 43.95/36.88/36.53 W/kg; p<0.001) compared to blocking players like Linemen (G1) and to the age matched reference population (RP). Only 53% of the healthy athletes would have been cleared for sport using the BIA test criteria, which highlights the challenging passing criteria. Despite significantly greater power measurements, scores of balance and agility were poorer compared to the reference group, especially for linemen. These data may serve as sport and position specific reference for high school American football players, instead of using the non-specific reference group data. cross-sectional study. IIb.

Google Trends™ and Quality of Information Analyses of Google™ Searches Pertaining to Concussion.

Sports-related concussions occur with high incidence in the United States. Google Trends™ (GT) analyses indicate changes of public interest in a topic over time, and can be correlated with incidence of health events such as concussion. Internet searches represent a primary means of patient education for many health topics, including concussion; however, the quality of medical information yielded by internet searches is variable and frequently of an inappropriate reading level. This study therefore aims to describe GT over time and evaluate the quality and readability of information produced by Google™ searches of the term "concussion." We identified a strong negative correlation from 2009 to 2016 between GT scores and total number of American high school football participants (R 2 = 0.8553) and participants per school (R 2 = 0.9533). Between 2004 and 2020, the monthly GT popularity score were variable (p = 3.193E-08), with September having the greatest scores, correlating with the height of American tackle football season. Applying five validated quality assessment scoring systems at two time points, it was confirmed that different sources yielded varying quality of information. Academic and non-profit healthcare sources demonstrated the highest quality metrics across two time points. There was significant variability of scores among the different scoring systems, however. The majority of searches at both time points yielded information that was rated as "fair" to "poor" in quality. Applying six readability tests, we revealed that only a single commercial website offered information written at or below the American Medical Association- recommended 6th-grade level for healthcare information. In summary, GT data analyses suggest that searches correlate with the American tackle football season and increased between 2009 and 2016, given that public interest in concussion increased and annual participation in football decreased. The quality of information yielded by Google™ searches and readability are inadequate, indicating the need for significant improvement.

Correction: Identifying Factors Associated with Head Impact Kinematics and Brain Strain in High School American Football via Instrumented Mouthguards

Correction: Identifying Factors Associated with Head Impact Kinematics and Brain Strain in High School American Football via Instrumented Mouthguards

Bilateral Ischial Tuberosity Stress Fractures in an Adolescent Football Player: A Case Report.

Pelvic stress fractures are rare, making up an estimated 1% to 7% of all stress fractures with the primary locations being the pubic rami, pubic symphysis, and sacrum. Two cases of stress fractures of the ischium have been previously described in the literature, with both occurring in the ischial body. In this case, a 17-year-old high school American football player presented with nonspecific pelvic pain and bilateral point tenderness on deep palpation of the ischial tuberosities. Advanced imaging identified bilateral ischial tuberosity stress fractures. This report outlines the diagnosis and management of the first reported case of bilateral ischial tuberosity stress fractures. We report how ischial tuberosity stress fractures present clinically, potential management strategies, and highlight the use of computed tomography imaging for pelvic stress fractures. Knowledge of unusual stress fracture locations may improve early diagnosis, limit complications, reduce healthcare costs, and promote an accelerated recovery time.

Sport-related Structural Brain Injury in High School and College American Football Athletes, 2002-2020: Effect of Lystedt Law.

A previous report revealed an average of 7.2 (0.67 per 100,000 participants) sport-related structural brain injuries (SRSBIs) with macroscopic lesions per year in high school (HS) and college football players. The Lystedt law and other rule changes have been implemented with intent to reduce the risk of brain injury in football. To update the profile of SRSBIs in HS and college football players and evaluate the efficacy of legislation intended to reduce brain injuries. Descriptive epidemiology study. Level 4. We retrospectively reviewed 18 academic years (July 2002 through June 2020) of SRSBIs catalogued by the National Registry of Catastrophic Sports Injuries. The incidence of SRSBIs was assessed at the HS level during the pre (July 2002 through June 2009), transitional (July 2009 through June 2014), and post (July 2014 through June 2020) universal adoption time periods of the Lystedt law. In addition, the incidence of SRSBIs during the second half of the study (2011-2012 through 2019-2020) was compared with the first half of the study (2002-2003 through 2010-2011). During the study period, there was a total of 228 SRSBIs (12.7 per year, 1.01 per 100,000 participants): 212 (93%, 11.8 per year, 1.00 per 100,000) in HS athletes and 16 (7%, 0.89 per year, 1.17 per 100,000) in college athletes. There were 52 fatalities (2.9 per year, 0.22 per 100,000 participants) with 46 (2.56 per year, 0.22 per 100,000) in HS athletes and 6 (0.33 per year, 0.43/100,000) in college athletes. There was no significant difference in risk of HS total SRSBIs or fatalities during the 3 Lystedt periods. The risk of combined SRSBI cases [relative risk (RR) = 1.22, P = 0.13] and fatalities (RR = 1.20, P = 0.52) was similar in the second half of the study compared with the first half of the study. Despite implementation of rule changes intended to reduce head injury, in particular the Lystedt law, the incidence of SRSBIs has remained unchanged. Further research is necessary to develop effective prevention programs for SRSBIs. SRSBIs remain a persistent problem in HS and college American football. The recent head injury rule changes have not been effective at reducing SRSBIs.

Poster 116: Traumatic Brain Injury in High School and College American Football Athletes, 2002-2019: Increasing Risk of Injury and Fatality

Objectives:A prior report revealed an average of 7.2 (0.67 per 100,000 participants) traumatic brain injuries (TBI) per year in high school (HS) and college football players from 1989 through 2002. Our goal is to update the profile of TBI in HS and college football players and evaluate the efficacy of state laws implemented to reduce brain injuries.Methods:We retrospectively reviewed 17 academic years (July 2002 through June 2019) of TBIs catalogued by the National Registry of Catastrophic Sports Injuries (NRCSI). Descriptive statistics were collected using Excel and SPSS. The incidence of TBI was compared with the prior 13-year period. In addition, the incidence of TBI was assessed at the HS level during the pre (2002-2009[BB3] [BI([4] [BI([5] ), transitional (2009-2014), and post (2014-2019) universal adoption time periods of the Lystedt laws. Multinomial logistic regression analyses were performed to determine the odds of TBI based on level of play, Lystedt law adoption eras, and position played.Results:During the study period, there was a total of 177 TBIs (10.4 per year, 0.82 per 100,000 participants): 164 (92.7%, 0.81 per 100,000, 9.65 per year) in HS athletes and 13 (6.6%, 0.96 per 100,000, 0.76 per year) in college athletes. The risk of TBI at the HS level was significantly higher than at the college level (1.99: 95% CI, 1.137-3.517, P<0.0001). Compared to the prior 13-year period, the risk of TBI during the study period was 1.29 (95% CI, 1.004-1.656, P=0.047) with a greater increase at the college (4.40: 95% CI, 0.993-19.5, P=0.051) than the HS level (1.22: 95% CI, 0.946-1.577, P=0.124). There were 51 fatalities (3 per year, 0.24 per 100,000 participants) with a risk of 1.63 (95% CI: 0.65-4.11, P = 0.3) at the college (n=5, 0.29 per year, 0.36/100,000) compared with the HS (n=46, 2.71 per year, 0.22 per 100,000) levels. The risk of a fatality in the current study compared with the prior study was 4.32 (95% CI: 2.05-9.09, P= 0.0001) with higher risks at both the HS (5.17, 95% CI: 2.21-12.1, P =0.0002) and college (1.8, 95% CI: 0.35-9.3, P = 0.48) levels. The incidence of TBI in HS increased significantly from the pre (0.57 per 100,000) to the transitional (0.78 per 100,000, OR = 4.7, P<0.001), and from the transitional to the post universal adoption (1.17 per 100,000, OR = 13.7, P<0.0001) eras of the Lystedt law. The most common positions among HS and college athletes suffering TBI were linebacker (26, 22.6%) and running back (20, 17.4%), and defensive back (16, 13.9%).Conclusions:The incidence of TBI has increased 29% during the 2002-2019 period compared to the prior 13-year period with a 440% and 22% rise in college and HS cases, respectively. The risk of fatality increased 432% compared to the prior 13-year period with an increase of 517% and 180% at the HS and college levels, respectively. The increased incidence of TBI at the HS level has occurred despite implementation of the Lystedt laws. Further research is necessary to determine the risk factors for TBI in order to develop prevention strategies.Figure 3B.Incidence Rates During Lystedt Law Adoption Eras

Physical demands and physiological strain of American football referees while officiating

ABSTRACT Objectives Certain occupations are associated with greater risk of triggering a sudden cardiac event because of high levels of physical exertion and extreme thermal environments in which they occur. The extent to which sports officials––particularly high school (HS) American football referees––experience these conditions is unknown. Forty-six male HS officials (72% White/Caucasian; age = 48 ± 12 years, body mass index = 31.7 ± 6.6 kg·m−2) were studied to quantify the physiological strain and physical demands of officiating. Methods Referee demographics (e.g., experience, habitual exercise), pre-game urine specific gravity (USG), thermal (peak core temperature [Tcore]) and cardiovascular (average heart rate [HR]) strain, kinematic activity (e.g., total distance, speed, mechanical intensity), and environmental conditions were measured during 10 regular season varsity HS football games (≈2.5 h each) in the Southeastern United States (average wet bulb globe temperature and relative humidity: 18.9 ± 6.0 °C and 78.2% ± 12.1%). Analyses included descriptive statistics, bivariate correlations, and linear regression. Results Referees covered 5.2 ± 1.2 km per game, eliciting average HR and peak Tcore of 71.5% ± 8.0% HRmax and 38.3 ± 0.5 °C, respectively; 38% began games dehydrated (USG = 1.026 ± 0.004). Multiple regression analyses revealed that obesity (β = 0.34), not participating in regular exercise (β = −0.36), and officiating at lower mechanical intensity (β = −0.33) predicted greater cardiovascular strain (all p ≤ 0.03). White/Caucasian race/ethnicity (β = 0.59), younger age (β = −0.46), and obesity (β = 0.28) predicted greater thermal strain (all p ≤ 0.01). Conclusion HS football referees experienced elevated levels of physiological strain while officiating, with individual factors modulating the magnitude of strain. Strategies aimed at reducing obesity, increasing exercise participation, and improving cardiovascular health should be emphasized to mitigate strain and prevent cardiac events.

Comparison of pre-high school and high school football quarterback injuries

ABSTRACT Objective To compare the common injuries of pre-high school American football quarterbacks (Pre-HS QBs) and high school American football quarterbacks (HS QBs) within the last 15 years. Methods A retrospective chart review was performed at a sports medicine clinic at a tertiary-level pediatric medical center. Pediatric and adolescent American football quarterback patients who sustained sports-related injuries were extracted. Injury status (acute vs. overuse), injured anatomic locations, injury types, and surgical status were compared by Pre-HS QBs (<14 years old) and HS QBs (14–18 years old). Results A total of 121 injuries were found in 118 male Pre-HS QBs (mean age: 12.4 ± 1.6), while 302 injuries were observed in 256 male HS QBs (mean age: 15.8 ± 1.4). Overall, nearly two-third (2/3) of injuries were acute (64.3%) while a little over one-third (1/3) of injuries were overuse in nature (35.7%), and there were no differences between Pre-HS and HS QBs (58.7% vs. 66.7%, p = 0.114). The top 3 injured anatomic locations for Pre-HS QBs were elbow (20.7%), shoulder (18.2%), and head/neck (14.0%). For HS QBs, the top 3 injured anatomic locations were shoulder (24.5%), knee (17.5%), and head/neck (15.2%). There were significant differences in proportion of elbow (20.7% vs. 10.6%, p = 0.006), hip/trunk/upper leg (10.7% vs. 3.3%, p = 0.002), and knee injuries (9.1% vs. 17.5%, p = 0.028) between Pre-HS and HS QBs. Pre-HS QBs had significantly more bony/cartilaginous/labral injuries than their older counterparts (60.3% vs. 46.3%, p = 0.009) while HS QBs experienced significantly more ligamentous injuries than Pre-HS QBs (14.2% vs. 5.8%, p = 0.015). Conclusions QB-associated injuries were distinctively different between Pre-HS and HS QBs. Future studies are warranted to investigate relatively high proportions of elbow injuries as well as bony/cartilaginous/labral injuries found in Pre-HS QBs.

American Football Position-Specific Neurometabolic Changes in High School Athletes: A Magnetic Resonance Spectroscopic Study.

Reports estimate between 1.6-3.8 million sports-related concussions occur annually, with 30% occurring in youth male American football athletes. Many studies report neurophysiological changes in these athletes, but the exact reasons for these changes remain elusive. Investigation of injury mechanics highlights a need to address how player position might impact these changes. Here, 55 high school American football athletes (20 linemen; 35 non-linemen) underwent magnetic resonance spectroscopy four times over the course of a football season-once prior to the season (Pre), twice during (In1, In2), and once following (Post) to quantify metabolites (N-acetyl aspartate, choline, creatine, myo-inositol, and glutamate/glutamine) in the dorsolateral prefrontal cortex (DLPFC) and primary motor cortex (M1). Head acceleration events (HAEs) were monitored at each practice and game. Spectroscopic and HAE data were analyzed by imaging session and player position. Linear regression analyses were conducted between metabolite levels and HAEs, and metabolite levels in football athletes were compared with age-and gender-matched non-contact athletes. Across-season (i.e., between Pre and In1, In2, Post), different DLPFC and M1 metabolites decreased (p < 0.05) according to player position (i.e., linemen vs. non-linemen). The majority of regression results involved DLPFC metabolites in linemen, where metabolite levels were higher from Pre to Post, with increasing HAE load. Comparisons with control athletes revealed higher metabolite levels in football athletes both before and after the season. This study highlights the importance of player position when conducting analyses on American football athletes and demonstrates elevated DLPFC and M1 brain metabolites in football athletes compared with control athletes at both Pre and Post, suggesting potential HAE-related neurocompensatory mechanisms.

Perceptual-Motor Efficiency and Concussion History Are Prospectively Associated With Injury Occurrences Among High School and Collegiate American Football Players.

Background:After a sport-related concussion (SRC), the risk for lower extremity injury is approximately 2 times greater, and the risk for another SRC may be as much as 3 to 5 times greater.Purpose:To assess the predictive validity of screening methods for identification of individual athletes who possess an elevated risk of SRC.Study Design:Case-control study; Level of evidence, 3.Methods:Metrics derived from a smartphone flanker test software application and self-ratings of both musculoskeletal function and overall wellness were acquired from American high school and college football players before study participation. Occurrences of core or lower extremity injury (CLEI) and SRC were documented for all practice sessions and games for 1 season. Receiver operating characteristic and logistic regression analyses were used to identify variables that provided the greatest predictive accuracy for CLEI or SRC occurrence.Results:Overall, there were 87 high school and 74 American college football players included in this study. At least 1 CLEI was sustained by 45% (39/87) of high school players and 55% (41/74) of college players. Predictors of CLEI included the flanker test conflict effect ≥69 milliseconds (odds ratio [OR], 2.12; 90% CI, 1.24-3.62) and a self-reported lifetime history of SRC (OR, 1.70; 90% CI, 0.90-3.23). Of players with neither risk factor, only 38% (29/77) sustained CLEI compared with 61% (51/84) of players with 1 or both of the risk factors (OR, 2.56; 90% CI, 1.50-4.36). SRC was sustained by 7 high school players and 3 college players. Predictors of SRC included the Overall Wellness Index score ≤78 (OR, 9.83; 90% CI, 3.17-30.50), number of postconcussion symptoms ≥4 (OR, 8.35; 90% CI, 2.71-25.72), the Sport Fitness Index score ≤78 (OR, 5.16; 90% CI, 1.70-15.65), history of SRC (OR, 4.03; 90% CI, 1.35-12.03), and the flanker test inverse efficiency ratio ≥1.7 (OR, 3.19; 90% CI, 1.08-9.47).Conclusion:Survey responses and smartphone flanker test metrics predicted greater injury incidence among individual football players classified as high-risk compared with that for players with a low-risk profile.

Head Impact Exposure in American High School Football and Ice Hockey: A Longitudinal Prospective Cohort Study

<h3>Research Objectives</h3> To prospectively investigate the relationship between head impact (HI) exposure, neuropsychological performance, and reported symptoms in youth football and ice hockey players in the United States. We hypothesized that exposure to greater linear and rotational forces would be associated with neuropsychological inefficiency and increased symptoms. <h3>Design</h3> Longitudinal prospective cohort over the course of one year. <h3>Setting</h3> General community. <h3>Participants</h3> Volunteer sample comprised of male student-athletes with current or planned participation in American football or ice hockey who were within 90 days of starting 10th or 11th grades (N=34). Those who had significant developmental, academic, or neurologic history or did not complete one year follow up (n=9) were excluded. <h3>Interventions</h3> Not applicable. <h3>Main Outcome Measures</h3> Linear and rotational acceleration/deceleration forces were measured via helmet sensors (football) and mouth guards (ice hockey). Participant background (past medical history of specific learning disorder, attention disorder, mood or anxiety disorder, or headache/migraine), neuropsychological testing (ImPACT, paper/pencil measures), concussion history, and symptom report (PCSS) were gathered during preseason (PS) and at one year follow up (FU). Neuropsychological inefficiency (NPI, Beauchamp, 2015) at FU and change in total reported symptoms were calculated. <h3>Results</h3> Participant background and previous concussion were associated with increased odds of NPI (all odds ratios=5.57-15.76, all ps=0.24-0.27) and symptom increase at FU (all OR=1.56-5.57, all p=0.26-0.85), albeit none were statistically significant. No significant associations were observed for HI exposure variables. <h3>Conclusions</h3> In this pilot study, we did not observe statistically significant associations between HI exposure and neuropsychological inefficiency or increased symptoms at one year follow up. Larger studies with a broader participant pool (e.g., additional contact sports, females) and longer-term follow-up are warranted to corroborate these findings. If the present findings are substantiated, results would support safe participation in contact sports. <h3>Author(s) Disclosures</h3> None.

Identifying Factors Associated with Head Impact Kinematics and Brain Strain in High School American Football via Instrumented Mouthguards.

Repeated head impact exposure and concussions are common in American football. Identifying the factors associated with high magnitude impacts aids in informing sport policy changes, improvements to protective equipment, and better understanding of the brain's response to mechanical loading. Recently, the Stanford Instrumented Mouthguard (MiG2.0) has seen several improvements in its accuracy in measuring head kinematics and its ability to correctly differentiate between true head impact events and false positives. Using this device, the present study sought to identify factors (e.g., player position, helmet model, direction of head acceleration, etc.) that are associated with head impact kinematics and brain strain in high school American football athletes. 116 athletes were monitored over a total of 888 athlete exposures. 602 total impacts were captured and verified by the MiG2.0's validated impact detection algorithm. Peak values of linear acceleration, angular velocity, and angular acceleration were obtained from the mouthguard kinematics. The kinematics were also entered into a previously developed finite element model of the human brain to compute the 95th percentile maximum principal strain. Overall, impacts were (mean ± SD) 34.0 ± 24.3 g for peak linear acceleration, 22.2 ± 15.4 rad/s for peak angular velocity, 2979.4 ± 3030.4 rad/s2 for peak angular acceleration, and 0.262 ± 0.241 for 95th percentile maximum principal strain. Statistical analyses revealed that impacts resulting in Forward head accelerations had higher magnitudes of peak kinematics and brain strain than Lateral or Rearward impacts and that athletes in skill positions sustained impacts of greater magnitude than athletes in line positions. 95th percentile maximum principal strain was significantly lower in the observed cohort of high school football athletes than previous reports of collegiate football athletes. No differences in impact magnitude were observed in athletes with or without previous concussion history, in athletes wearing different helmet models, or in junior varsity or varsity athletes. This study presents novel information on head acceleration events and their resulting brain strain in high school American football from our advanced, validated method of measuring head kinematics via instrumented mouthguard technology.

Using Dynamics of Eye Movements, Speech Articulation and Brain Activity to Predict and Track mTBI Screening Outcomes

Repeated subconcussive blows to the head during sports or other contact activities may have a cumulative and long lasting effect on cognitive functioning. Unobtrusive measurement and tracking of cognitive functioning is needed to enable preventative interventions for people at elevated risk of concussive injury. The focus of the present study is to investigate the potential for using passive measurements of fine motor movements (smooth pursuit eye tracking and read speech) and resting state brain activity (measured using fMRI) to complement existing diagnostic tools, such as the Immediate Post-concussion Assessment and Cognitive Testing (ImPACT), that are used for this purpose. Thirty-one high school American football and soccer athletes were tracked through the course of a sports season. Hypotheses were that (1) measures of complexity of fine motor coordination and of resting state brain activity are predictive of cognitive functioning measured by the ImPACT test, and (2) within-subject changes in these measures over the course of a sports season are predictive of changes in ImPACT scores. The first principal component of the six ImPACT composite scores was used as a latent factor that represents cognitive functioning. This latent factor was positively correlated with four of the ImPACT composites: verbal memory, visual memory, visual motor speed and reaction speed. Strong correlations, ranging between r = 0.26 and r = 0.49, were found between this latent factor and complexity features derived from each sensor modality. Based on a regression model, the complexity features were combined across sensor modalities and used to predict the latent factor on out-of-sample subjects. The predictions correlated with the true latent factor with r = 0.71. Within-subject changes over time were predicted with r = 0.34. These results indicate the potential to predict cognitive performance from passive monitoring of fine motor movements and brain activity, offering initial support for future application in detection of performance deficits associated with subconcussive events.

The effects of lower-limb wearable resistance on sprint performance in high school American football athletes: A nine-week training study

Time constraints often result in the challenge to fit desired programming into training time allotments. Wearable resistance (WR) may be an option to optimise the training content in function of constrained training time. The purpose of this study was to determine the effects of a lower-limb WR sprint running training intervention on athlete speed capabilities following a nine-week off-season, low volume training period within a sample of American football high school athletes. Nineteen athletes completed pre- and post-intervention testing of two maximal effort 30 m sprints. Horizontal force-velocity mechanical profiling variables, sprint times, and maximal velocity were calculated from sprint running velocity data collected by a radar device. The athletes completed seventeen dedicated sprint training sessions during the off-season. The intervention (WR) group completed the sessions with 1% body mass load attached to the shanks (i.e. 0.50% body mass load on each limb). The control group completed the same training sessions unloaded. Post-intervention, no statistically significant between group differences were observed ( p &gt; 0.05). However, athletes in both groups experienced increases in velocity measures following the sprint training. The greater adjusted mean theoretical maximal velocity scores ( p &gt; 0.05; ES = 0.30) found for the WR group compared to the control group at post-intervention may suggest that WR amplifies the nuances of the training protocol itself. Coaches can consider using lower-limb WR training to increase in-session workloads during periods of low volume training but more research is needed to better understand to what extent WR training might provide an added value to optimise both the training content and planning, as well as the athlete’s training response in order to improve sprint running performance.

Using Oculomotor Features to Predict Changes in Optic Nerve Sheath Diameter and ImPACT Scores From Contact-Sport Athletes.

There is mounting evidence linking the cumulative effects of repetitive head impacts to neuro-degenerative conditions. Robust clinical assessment tools to identify mild traumatic brain injuries are needed to assist with timely diagnosis for return-to-field decisions and appropriately guide rehabilitation. The focus of the present study is to investigate the potential for oculomotor features to complement existing diagnostic tools, such as measurements of Optic Nerve Sheath Diameter (ONSD) and Immediate Post-concussion Assessment and Cognitive Testing (ImPACT). Thirty-one high school American football and soccer athletes were tracked through the course of a sports season. Given the high risk of repetitive head impacts associated with both soccer and football, our hypotheses were that (1) ONSD and ImPACT scores would worsen through the season and (2) oculomotor features would effectively capture both neurophysiological changes reflected by ONSD and neuro-functional status assessed via ImPACT. Oculomotor features were used as input to Linear Mixed-Effects Regression models to predict ONSD and ImPACT scores as outcomes. Prediction accuracy was evaluated to identify explicit relationships between eye movements, ONSD, and ImPACT scores. Significant Pearson correlations were observed between predicted and actual outcomes for ONSD (Raw = 0.70; Normalized = 0.45) and for ImPACT (Raw = 0.86; Normalized = 0.71), demonstrating the capability of oculomotor features to capture neurological changes detected by both ONSD and ImPACT. The most predictive features were found to relate to motor control and visual-motor processing. In future work, oculomotor models, linking neural structures to oculomotor function, can be built to gain extended mechanistic insights into neurophysiological changes observed through seasons of participation in contact sports.