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The process of manually annotating sports footage is a demanding one. In American football alone, coaches spend thousands of hours reviewing and analyzing videos each season. We aim to automate this process by developing a system that generates comprehensive statistical reports from full-length football game videos. Having previously demonstrated the proof of concept for our system, here, we present optimizations to our preprocessing techniques along with an inventive method for multi-person event detection in sports videos. Employing a long short-term memory (LSTM)-based architecture to detect the snap in American football, we achieve an outstanding LSI (Levenshtein similarity index) of 0.9445, suggesting a normalized difference of less than 0.06 between predictions and ground truth labels. We also illustrate the utility of snap detection as a means of identifying the offensive players' assuming of formation. Our results exhibit not only the success of our unique approach and underlying optimizations but also the potential for continued robustness as we pursue the development of our remaining system components. [ABSTRACT FROM AUTHOR]

We analyse changes in the National Football League (NFL) due to ghost games in 2020. The home bias disappears as expected. This also applies to semi-ghost games with significantly fewer spectators than regular games and to referee decisions regarding penalties. [ABSTRACT FROM AUTHOR]

Purpose: Wearable sensors are used to measure head impact exposure in sports. The Head Impact Telemetry (HIT) System is a helmet-mounted system that has been commonly utilized to measure head impacts in American football. Advancements in sensor technology have fueled the development of alternative sensor methods such as instrumented mouthguards. The objective of this study was to compare peak magnitude measured from high school football athletes dually instrumented with the HIT System and a mouthpiece-based sensor system. Methods: Data was collected at all contact practices and competitions over a single season of spring football. Recorded events were observed and identified on video and paired using event timestamps. Paired events were further stratified by removing mouthpiece events with peak resultant linear acceleration below 10 g and events with contact to the facemask or body of athletes. Results: A total of 133 paired events were analyzed in the results. There was a median difference (mouthpiece subtracted from HIT System) in peak resultant linear and rotational acceleration for concurrently measured events of 7.3 g and 189 rad/s2. Greater magnitude events resulted in larger kinematic differences between sensors and a Bland Altman analysis found a mean bias of 8.8 g and 104 rad/s2, respectively. Conclusion: If the mouthpiece-based sensor is considered close to truth, the results of this study are consistent with previous HIT System validation studies indicating low error on average but high scatter across individual events. Future researchers should be mindful of sensor limitations when comparing results collected using varying sensor technologies. [ABSTRACT FROM AUTHOR]

American football is one of the most popular team sports in the United States. There are approximately 16,000 high school and 890 college football teams, and each team plays around 10–14 games per football season. Contrary to most casual fans' views, American football is more than speed and power, it requires preparation and strategies. Coaches analyze hours of video of their own and opponents' games to extract important information such as offensive play formations, personnel packages and opposing coaches' tendency to gain competitive advantages. This time-consuming and slow process called "tagging" takes away the coaches' time from other duties and limits the players' time for preparation and training. In this work, we created three datasets for our experiments to demonstrate the importance of player detection accuracy, which is easily affected by camera placement and player occlusion issues. We applied a unique data augmentation technique to generate data for each specific experiment. Our model achieved a remarkable 98.52% accuracy in play type recognition and 92.38% accuracy in player position recognition for the experiment that assumes no missing players or no occlusion problem, which could be achieved by placing the camera high above the football field. [ABSTRACT FROM AUTHOR]

High-quality cutting technique is essential for agility development and safer cuttings in adolescent athletes. Certain sidestep techniques and kinematics are characteristic of high movement quality and are associated with both, faster performance and lower knee joint loading (i.e., reduced anterior cruciate ligament injury risk). The aim of this study was to determine the effects of a 6-week, side step, technique modification training intervention targeting specific kinematics on agility performance and movement quality. Twenty-two adolescent American football players were recruited for a nonrandomized, controlled, intervention study. For 6 weeks, an intervention group (IG) of 11 players participated in 25-minute cutting technique training sessions integrated into team training twice a week, whereas a control group (CG) of 11 players continued their usual training routine. Agility performance was assessed based on percentage-based change of direction deficit (CODDp) obtained during reactive agility tests at 45° and 90° angles. The Cutting Movement Assessment Score (CMAS) qualitative screening tool was used to assess 2D high-speed videos of the cuts for movement quality. The significance level was set at α = 0.01. The intervention effectively altered players' sidestep technique irrespective of cutting angle with large time x group interaction effects observed for CMAS (ηp² = 0.82). Statistical and practical significant improvements in CMAS pre-to-post intervention were evident in the IG (-2.30 ≤ g ≤ -1.75; 313.87 ≤ BF10 ≤ 2,342.00), whereas deteriorations were found in the CG for 90° (g = 1.38; BF10 = 64.21). However, in both groups, no statistically significant differences in CODDp were observed pre-to-post intervention (0.019 ≤ p ≤ 0.586; 0.34 ≤ BF10 ≤ 3.59). The cutting technique modification training meaningfully improved movement quality, without negatively affecting agility performance, and can be used by practitioners to foster a safe technical foundation for subsequent agility development in adolescent athletes. [ABSTRACT FROM AUTHOR]

Considering that diagnostic decisions about mTBI are often predicated on clinical symptom criteria, it is imperative to determine which initial presentation features of mTBI have prognostic significance for identifying those at high risk for long-term functional impairment. Zoom interview Participants: Male, former NCAA Division I, and professional-level National Football League (NFL) athletes (n = 177) between the ages of 27 and 85 (M = 54.1, SD = 14.7). Cross-sectional case-control. Main Measures: History of mild TBI, history of loss of consciousness (LOC), depression symptoms, insomnia, neurobehavioral symptoms. Number of mTBI exposures did not predict neurobehavioral symptoms (B = 0.21, SE = 0.18, p = 0.23), but number of mTBI + LOC events did (B = 2.27, SE = 0.64, p = <.001). Further analysis revealed that the number of mTBI + LOC events predicted neurobehavioral symptoms indirectly through both depression (B = 0.85, 95% CI = [0.27, 1.52) and insomnia (B = 0.81, 95% CI = [0.3, 1.4]). Further, the direct effect of mTBI + LOC events on neurobehavioral symptoms became non-significant when depression and insomnia were added to the model (B = 0.78, SE = 0.45, p = 0.08). Findings support LOC at time of injury as an important predictor of long-term outcomes. Additionally, results suggest depression and insomnia as potential mediators in the association between mTBI + LOC and neurobehavioral symptoms. These findings provide justification for early depression and insomnia symptom monitoring following mTBI + LOC. [ABSTRACT FROM AUTHOR]

Background: American football is the most popular sport in the United States, with over 5.6 million people >6 years old playing the sport. Fractures in American football athletes are significant, as they compromise an athlete's performance and can also lead to prolonged recovery periods, affecting team dynamics and player careers. Analyzing these injuries is critical to evaluate preventive measures and tailor rehabilitation strategies to ensure the well-being and sustained peak performance of football athletes on and off the field. Purpose: To analyze the trend of American football fractures by body site, sex, and age in amateur athletes over a 20-year period between 2002 and 2021. Study Design: Descriptive epidemiology study. Methods: The National Electronic Injury Surveillance System (NEISS) database was queried to characterize football-related fractures and injuries from 2002 to 2021 in patients aged 0-99 years old. National injury estimates were calculated using sample weights. Chi-square analysis and one-way ANOVA were performed to compare categorical variables. Results: Of 56,809 cases of American football-related fractures over 20 years, patients aged 10 to 14 years had the highest incidence of fractures, composing 41.2% of all fractures (n = 23,389), and patients aged <18 years represented 88.8% of all fractures (n = 50,457). The median age of players when fractures occurred was 13 years. Upper extremity fractures (n = 41,863 [73.7%]) were the most common fracture reported compared with lower extremity and head, neck, and trunk fractures. Among upper extremity fractures, finger fractures had the highest prevalence (35.6%), followed by lower arm fractures (19.9%) and wrist fractures (13%). While most cases resulted in release after treatment (93.1%), 5.9% resulted in treatment and hospitalization. When analyzing trends in American football-related fractures over time, we observed the largest number of fractures in 2006 (n = 3664), while the smallest number of fractures occurred in 2020 (n = 1313). Also, a downward trend was found in American football-related fractures since 2006, with a mean of 101 fewer fractures each year. Conclusion: Our analysis showed that American football-related fractures diagnosed in the emergency department in the United States were most likely to occur in pediatric patients (10-18 years old). In addition, patients experiencing American football-related fractures were most likely to have an upper extremity fracture and not require hospitalization. The trend in American football-related fractures has been decreasing since 2006. [ABSTRACT FROM AUTHOR]

Many head acceleration events (HAEs) observed in youth football emanate from a practice environment. This study aimed to evaluate HAEs in youth football practice drills using a mouthpiece-based sensor, differentiating between inertial and direct HAEs. Head acceleration data were collected from athletes participating on 2 youth football teams (ages 11–13 y) using an instrumented mouthpiece-based sensor during all practice sessions in a single season. Video was recorded and analyzed to verify and assign HAEs to specific practice drill characteristics, including drill intensity, drill classification, and drill type. HAEs were quantified in terms of HAEs per athlete per minute and peak linear and rotational acceleration and rotational velocity. Mixed-effects models were used to evaluate the differences in kinematics, and generalized linear models were used to assess differences in HAE frequency between drill categories. A total of 3237 HAEs were verified and evaluated from 29 football athletes enrolled in this study. Head kinematics varied significantly between drill categorizations. HAEs collected at higher intensities resulted in significantly greater kinematics than lower-intensity drills. The results of this study add to the growing body of evidence informing evidence-based strategies to reduce head impact exposure and concussion risk in youth football practices. [ABSTRACT FROM AUTHOR]

Each year in the United States, many factors are considered in the National Football League's draft process, including scouting reports, interviews, medical tests, and measures of players' strength, speed, anthropometry, and personality. Recently, an increased emphasis has been placed on players' psychometrically measured cognitive abilities. Historically, offensive linemen have been excluded from NFL research, since they do not have individual performance statistics. In this study, we attempted to fill that research gap by investigating correlates of offensive linemen's measured vigilance/impulsivity. We obtained archival player data from 85 offensive linemen in the years from 2014–2021 prior to each of these players' NFL draft. We then used false start penalties per game (FSPG) as an index of their vigilance/impulsivity (and general success) on the field, and we related those values to Reaction Time tests through hierarchical multiple regression analyses. After controlling for draft placement, these players' higher accuracy on a Choice Reaction Time task accounted for a statistically significant percentage of the variance associated with their FSPG statistics. We discuss the practical utility for player development of these and other cognitive assessments now used in the NFL. [ABSTRACT FROM AUTHOR]

In American football, hand injuries have been shown to negatively impact performance. The purpose of this study is to characterize the prevalence and severity of hand injuries in National Football League (NFL) players. A public online database was utilized to identify hand injuries in NFL players from 2009–2010 to 2019–2020. The primary outcome was to analyze the overall incidence of hand injuries (including wrist, metacarpus, finger, and thumb), injury type by each aforementioned anatomic location, and player position. Injury severity was evaluated based on percentage of injuries in which players returned to play (RTP), number of games missed before RTP, and the percentage of injuries resulting in the player being placed on injured reserve (IR). Of the 6,127 players included, 847 (13.8%) players sustained a hand injury, of which 24.8%, 34.3%, 17.9%, and 22.9% occurred at the wrist, metacarpus, finger, and thumb, respectively. Of the injured players, 97.4% returned to play following their injury, 14.8% were put on IR, and an average of 1.7 (SD 3.3) games were missed. Quarterbacks were the most likely to sustain hand injuries at all anatomic locations. Wrist injuries were associated with the lowest RTP rate (93.3%), the most players placed on injured reserve (28.6%), and the greatest number of games missed (mean 2.5, SD 4.2). Hand injuries decreased in prevalence by 65.6% over the 11 NFL seasons evaluated. This trend coincides with the implementation of several safety rules that relate to components of play involving the hands. Quarterbacks experienced the greatest prevalence and severity for all hand injuries. Wrist injuries represent the anatomic location associated with the greatest severity. These findings may be able to inform tailored injury prevention practices by position, and advocate for the further adoption of safety rules to protect players from further injury. [ABSTRACT FROM AUTHOR]

Recorded head kinematics from head-impact measurement devices (HIMd) are pivotal for evaluating brain stress and strain through head finite element models (hFEM). The variability in kinematic recording windows across HIMd presents challenges as they yield inconsistent hFEM responses. Despite establishing an ideal recording window for maximum principal strain (MPS) in brain tissue, uncertainties persist about the impact characteristics influencing vulnerability when this window is shortened. This study aimed to scrutinize factors within impact kinematics affecting the reliability of different recording windows on whole-brain peak MPS using a validated hFEM. Utilizing 53 on-field head impacts recorded via an instrumented mouthguard during a Canadian varsity football game, 10 recording windows were investigated with varying pre- and post-impact-trigger durations. Tukey pair-wise comparisons revealed no statistically significant differences in MPS responses for the different recording windows. However, specific impacts showed marked variability up to 40%. It was found, through correlation analyses, that impacts with lower peak linear acceleration exhibited greater response variability across different pre-trigger durations. Signal shape, analyzed through spectral analysis, influenced the time required for MPS development, resulting in specific impacts requiring a prolonged post-trigger duration. This study adds to the existing consensus on standardizing HIMd acquisition time windows and sheds light on impact characteristics leading to peak MPS variation across different head impact kinematic recording windows. Considering impact characteristics in research assessments is crucial, as certain impacts, affected by recording duration, may lead to significant errors in peak MPS responses during cumulative longitudinal exposure assessments. [ABSTRACT FROM AUTHOR]

Student-athletes are often treated differently and inequitably based on their race/ethnicity. For example, Black student-athletes often face unjust stereotyping and discrimination because they are seen for their athletic achievements over their academic achievements compared to White student-athletes. Using in-game broadcast data, Black athletes are also discussed differently than White athletes, with disparities in how broadcasters focus on players' physical and cognitive abilities. The current paper draws on and extends this literature by using natural language processing techniques to identify how experts communicate about different National Football League (NFL) prospects. A decade of data (2014-2023), including nearly 4,000 draft profiles, suggested writers attending to Black draftees used fewer positive emotions in player narratives than writers attending to White draftees. Narratives of White players also mentioned the NFL more than narratives of Black players, revealing a possible disparity in perceived belonging to the league. Implications for theory and equity in sport are discussed. [ABSTRACT FROM AUTHOR]

Introduction: With recent increases in the popularity of studying the physical construct of horizontal deceleration performance in team-sport athletes, the aim of the present study was to assess the inter-rater and intra-rater reliability of processing and quantifying horizontal deceleration ability using radar technology. Methods: Data from 92 NCAA Division 1 athletes from two different athletic teams (American football and Lacrosse) were used for the present investigation. All athletes performed two trials of the modified acceleration to deceleration assessment (ADA), which consisted of a maximal 10 m sprint acceleration, followed by a rapid deceleration. Four individual raters manually processed raw, radar-derived instantaneous velocity data for the ADA, and an automated script was used to calculate metrics of interest. Results: Primary study findings suggest moderate to excellent levels of agreement (ICC = 0.56-0.91) for maximal horizontal deceleration metrics between the four individual raters. The intra-rater analyses revealed poor to excellent consistency (ICC = 0.31-0.94) between ADA trials, with CV%'s ranging from 3.1% to 13.2%, depending on the respective metric and rater. Discussion: Our data suggests that if a foundational understanding and agreement of manual data processing procedures for radar-derived data is given between raters, metrics may be interpreted with moderate to excellent levels of confidence. However, when possible, and when using the Stalker ATS radar technology, authors recommend that practitioners use one trained individual to manually process raw data. Ideally, this process should become fully automated, based on selected filters or algorithms, rather than the subjectivity of the rater. [ABSTRACT FROM AUTHOR]

Objective: In this study, we aimed to evaluate the relationship between blood pressure, left ventricular (LV) mass, and systolic function in American football (AF) players in Türkiye using deformation imaging and to compare it with conventional echocardiographic methods. Methods: AF players admitted to the Gazi University, Cardiology Unit between January 2021 and May 2023 were included in our study. The players were grouped as linemen or non-linemen according to their field positions. LV mass and ejection fraction (EF) were assessed using blood pressure measurements and conventional methods. Deformation analysis was performed by two-dimensional speckle tracking echocardiography, and LV torsion and global longitudinal strain values were calculated. Deformation analyses were compared with blood pressure and LV EF. Results: Players in the lineman position had higher blood pressure measurements. Although both groups of players had similar and intact LV EF values, players in the lineman position had significant changes in LV mass, LV global longitudinal strain, and LV torsion in relation to blood pressure measurements. Conclusion: AF players are at risk of hypertension. LV hypertrophy due to hypertension causes systolic dysfunction. Deformation analysis methods can detect subclinical myocardial damage even if the EF is intact. [ABSTRACT FROM AUTHOR]

Objective: This prospective cohort study aimed to investigate the association between head impact exposure (HIE) and neuropsychological sequelae in high school football and ice hockey players over 1 year. Setting: Community sample. Participants: A cohort of 52 adolescent American football and ice hockey players were enrolled in the study, with a final study sample of 35 included in analyses. Design: The study followed a prospective cohort design, with participants undergoing neuropsychological screening and accelerometer-based measurement of HIE over 1 season. Main Measures: Changes in cognition, emotions, behavior, and reported symptoms were assessed using standardized neuropsychological tests and self-reported questionnaires. Results: Cumulative HIE was not consistently associated with changes in cognition, emotions, behavior, or reported symptoms. However, it was linked to an isolated measure of processing speed, showing inconsistent results based on the type of HIE. History of previous concussion was associated with worsened verbal memory recognition (ImPACT Verbal Memory) but not on a more robust measure of verbal memory (California Verbal Learning Test [CVLT]). Reported attention-deficit/hyperactivity disorder history predicted improved neurocognitive change scores. No associations were found between reported history of anxiety/depression or headaches/migraines and neuropsychological change scores. Conclusion: Overall, our findings do not support the hypothesis that greater HIE is associated with an increase in neuropsychological sequelae over time in adolescent football and ice hockey players. The results align with the existing literature, indicating that HIE over 1 season of youth sports is not consistently associated with significant neuropsychological changes. However, the study is limited by a small sample size, attrition over time, and the absence of performance validity testing for neurocognitive measures. Future studies with larger and more diverse samples, longer follow-up, and integration of advanced imaging and biomarkers are needed to comprehensively understand the relationship between HIE and neurobehavioral outcomes. Findings can inform guidelines for safe youth participation in contact sports while promoting the associated health and psychosocial benefits. [ABSTRACT FROM AUTHOR]

American football players consume large quantities of animal-sourced protein in adherence with traditional recommendations to maximize muscle development and athletic performance. This contrasts with dietary guidelines, which recommend reducing meat intake and increasing consumption of plant-based foods to promote health and reduce the risk of chronic disease. The capacity of completely plant-based diets to meet the nutritional needs of American football players has not been studied. This modeling study scaled dietary data from a large cohort following completely plant-based diets to meet the energy requirements of professional American football players to determine whether protein, leucine, and micronutrient needs for physical performance and health were met. The Cunningham equation was used to estimate calorie requirements. Nutrient intakes from the Adventist Health Study 2 were then scaled to this calorie level. Protein values ranged from 1.6–2.2 g/kg/day and leucine values ranged from 3.8–4.1 g/meal at each of four daily meals, therefore meeting and exceeding levels theorized to maximize muscle mass, muscle strength, and muscle protein synthesis, respectively. Plant-based diets scaled to meet the energy needs of professional American football players satisfied protein, leucine, and micronutrient requirements for muscle development and athletic performance. These findings suggest that completely plant-based diets could bridge the gap between dietary recommendations for chronic disease prevention and athletic performance in American football players. [ABSTRACT FROM AUTHOR]

In this study, to discuss the influence of concussion risk from the long-term use of American football helmets on collegiate teams, accident cases during the game are replicated based on game videos by simulations using whole-body numerical models and helmeted finite element human head models. The concussion risks caused by collisions were estimated using the mechanical parameters inside the skull obtained from finite element analyses. In the analyses, the different material properties of helmets identified by free-fall experiments using headform impactor-embedded helmets were used to represent brand-new and long-term-use helmets. After analyzing the five cases, it was observed that wearing a new helmet instead of a long-term-use one resulted in a reduction in the risk of concussion by 1 to 44%. More energy is attenuated by the deformation of the liners of the brand-new helmet, so the energy transferred to the head is smaller than that when wearing the long-term-use helmet. Thus, the long-term use of the helmet reduces its ability to protect the head. [ABSTRACT FROM AUTHOR]

The wet bulb globe temperature (WBGT) is widely used in athletics for assessing heat stress. Sports governing bodies provide a wide variety of recommendations on how often to take WBGT measurements during activities like practices and competitions. This can leave coaching staff and other sports medicine personnel in a quandary as to what is the "best practice." Our study is the first to use a large dataset to quantify the variability of WBGT within practice and competition sessions, and to identify the impact of using different measurement rates on the WBGT. The study leverages 6 years of data from thousands of American football practice and competition sessions from across Georgia, USA. We observed that, on average, WBGTs are coolest in the morning (26.67°C) and evening (24.84°C), and hottest in the midday (30.23°C) and afternoon (27.21°C). The variability within sessions tended to be greater for morning, midday, and afternoon than evenings, with session standard deviations of 0.96°C to 1.27°C and ranges of 2.67°C to 3.55°C when controlling for duration. WBGTs also tended to increase over time in morning sessions and decrease over time during afternoon and evening sessions. These changes are clinically important. We found that Georgia High School Association (GHSA) WBGT activity modification categories often changed during sessions, especially in the morning, midday, and afternoon where a change in GHSA category of ≥1 occurred in 57% to 76% of sessions. Considering this variability, our results indicate that more frequent measurements better capture maximum WBGT values over a session and reduce the likelihood of misclassifying activity modification. [ABSTRACT FROM AUTHOR]

Objective: This observational study examines the associated risk for concussion following ‘lowering the helmet to initiate contact’ penalties in the National Football League. Methods: Using officially published injury data on the National Football League (NFL) website, the authors reviewed NFL Players diagnosed with a concussion from 2015 to 2022 and who received a ‘lowering the helmet to initiate contact’ penalty from 2018 to 2020. Reported concussions were evaluated for association with ‘lowering the helmet to initiate contact’ penalties. The Friedman test assessed overall differences between the years. Pairwise comparisons were performed using the Wilcoxon signed-rank test with a Bonferroni correction to adjust for multiple comparisons. Results: The average incidence of all concussions per play was 0.45% for regular-season games. From 2018 to 2020, 86 lowering the helmet to initiate contact penalties were called. Three of 86 penalties resulted in concussions, with a 3.5% incidence. The Friedman test indicated significant differences in concussion trends across the years (χ2 = 16.0, p = 0.0003). Pairwise analysis with the Wilcoxon signed-rank test and adjusted for multiple comparisons with a Bonferroni correction (α = 0.05/28 = 0.0018) showed no statistically significant differences between years. There was a significant negative correlation of overall concussion incidence per year. Conclusions: The incidence of concussion with players penalized for lowering the helmet to initiate contact is greater than the overall incidence of concussions in all plays. While there is no difference in total concussions that occur, the concussion rate has a significant negative trend between 2015 and 2022. However, it is difficult to analyze the nonimmediate effects of this penalty on players’ intended play and practice, which may further decrease concussions.

In American football, a pass rush is an attempt by the defensive team to disrupt the offense and prevent the quarterback (QB) from completing a pass. Existing metrics for assessing pass rush performance are either discrete-time quantities or based on subjective judgment. Using player tracking data, we propose STRAIN, a novel metric for evaluating pass rushers in the National Football League (NFL) at the continuous-time within-play level. Inspired by the concept of strain rate in materials science, STRAIN is a simple and interpretable means for measuring defensive pressure in football. It is a directly observed statistic as a function of two features: the distance between the pass rusher and QB, and the rate at which this distance is being reduced. Our metric possesses great predictability of pressure and stability over time. We also fit a multilevel model for STRAIN to understand the defensive pressure contribution of every pass rusher at the play-level. We apply our approach to NFL data and present results for the first eight weeks of the 2021 regular season. In particular, we provide comparisons of STRAIN for different defensive positions and play outcomes, and rankings of the NFL's best pass rushers according to our metric. [ABSTRACT FROM AUTHOR]

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Objectives: Hamstring strain injuries (HSI) are common among football and soccer athletes. Eccentric strength imbalance is considered a contributing factor for HSI. There is, however, a paucity of data on hamstring imbalances of soccer and American football athletes as they age and advance in skill level. High school athletes will display greater interlimb discrepancies compared with collegiate and professional athletes. In addition, soccer athletes will exhibit greater hamstring asymmetry than American football athletes. Methods: Hamstring testing was performed on soccer and American football athletes using the NordBord Hamstring Testing System (Vald Performance, Albion, Australia). Age, sex, weight, sport specialization, and sport level were recorded. Maximum hamstring forces (N), torque (N · m), and work (N · s) were measured. Hamstring imbalance (%) was calculated by dividing the absolute value of the difference in leg forces divided by their sum. One-way analysis of variance and independent sample t tests compared measurements between athlete groups. Results: A total of 631 athletes completed measurements, including 88 high school male soccer, 25 college male soccer, 23 professional male soccer, 83 high school female soccer, 28 college female soccer, 288 high school football, and 96 college football athletes. High school soccer players displayed significantly greater imbalances for torque (P = 0.03) and work (P < 0.01) than football athletes. Imbalances for maximum force (P = 0.035), torque (P = 0.018), and work (P = 0.033) were significantly higher for male soccer athletes in high school compared with college- and professional-level athletes. Female high school soccer players had significantly higher imbalance in torque (P = 0.045) and work (P = 0.001) compared with female collegiate soccer players. Football athletes did not experience significant changes in force imbalances between skill levels. Conclusions: High school soccer athletes exhibit greater hamstring imbalances than football athletes. Higher levels of play in soccer, for both male and female athletes, correlate with less hamstring asymmetry. [ABSTRACT FROM AUTHOR]

Sport coaches increasingly rely on external load metrics for designing effective training programs. However, their accuracy in estimating internal load is inconsistent, and their ability to predict autonomic nervous system (ANS) deterioration is unknown. This study aimed to evaluate the relationships between internal and external training load metrics and ANS recovery and function in college football players. Football athletes were recruited from a D1 college in the southeastern US and prospectively followed for 27 weeks. Internal load was estimated via exercise cardiac load (ECL; average training heartrate (HR) × session duration) and measured with an armband monitor equipped with electrocardiographic capabilities (Warfighter MonitorTM (WFM), Tiger Tech Solutions, Miami, FL, USA). External load was estimated via the summation and rate of acceleration and decelerations as measured by a triaxial accelerometer using the WFM and an accelerometer-based (ACCEL) device (Catapult Player Load, Catapult Sports, Melbourne, Australia) worn on the mid-upper back. Baseline HR, HR variability (HRV) and HR recovery served as the indicators for ANS recovery and function, respectively. For HRV, two, time-domain metrics were measured: the standard deviation of the NN interval (SDNN) and root mean square of the standard deviation of the NN interval (rMSSD). Linear regression models evaluated the associations between ECL, ACCEL, and the indicators of ANS recovery and function acutely (24 h) and cumulatively (one- and two-week). Athletes (n = 71) were male and, on average, 21.3 ± 1.4 years of age. Acute ECL elicited stronger associations for 24 h baseline HR (R2 0.19 vs. 0.03), HR recovery (R2 0.38 vs. 0.07), SDNN (R2 0.19 vs. 0.02) and rMSSD (R2 0.19 vs. 0.02) compared to ACCEL. Similar results were found for one-week: 24 h baseline HR (R2 0.48 vs. 0.05), HR recovery (R2 0.55 vs. 0.05), SDNN (R2 0.47 vs. 0.05) and rMSSD (R2 0.47 vs. 0.05) and two-week cumulative exposures: 24 h baseline HR (R2 0.52 vs. 0.003), HR recovery (R2 0.57 vs. 0.05), SDNN (R2 0.52 vs. 0.003) and rMSSD (R2 0.52 vs. 0.002). Lastly, the ACCEL devices weakly correlated with ECL (rho = 0.47 and 0.43, p < 0.005). Our findings demonstrate that ACCEL poorly predicted ANS deterioration and underestimated internal training load. ACCEL devices may "miss" the finite window for preventing ANS deterioration by potentially misestimating training loads acutely and cumulatively. [ABSTRACT FROM AUTHOR]

IntroductionWith recent increases in the popularity of studying the physical construct of horizontal deceleration performance in team-sport athletes, the aim of the present study was to assess the inter-rater and intra-rater reliability of processing and quantifying horizontal deceleration ability using radar technology.MethodsData from 92 NCAA Division 1 athletes from two different athletic teams (American football and Lacrosse) were used for the present investigation. All athletes performed two trials of the modified acceleration to deceleration assessment (ADA), which consisted of a maximal 10 m sprint acceleration, followed by a rapid deceleration. Four individual raters manually processed raw, radar-derived instantaneous velocity data for the ADA, and an automated script was used to calculate metrics of interest.ResultsPrimary study findings suggest moderate to excellent levels of agreement (ICC = 0.56–0.91) for maximal horizontal deceleration metrics between the four individual raters. The intra-rater analyses revealed poor to excellent consistency (ICC = 0.31–0.94) between ADA trials, with CV%'s ranging from 3.1% to 13.2%, depending on the respective metric and rater.DiscussionOur data suggests that if a foundational understanding and agreement of manual data processing procedures for radar-derived data is given between raters, metrics may be interpreted with moderate to excellent levels of confidence. However, when possible, and when using the Stalker ATS radar technology, authors recommend that practitioners use one trained individual to manually process raw data. Ideally, this process should become fully automated, based on selected filters or algorithms, rather than the subjectivity of the rater.

Abstract Background Repetitive traumatic brain injuries in American football players (AFPs) can lead to the neurodegenerative disease chronic traumatic encephalopathy (CTE). Clinical symptoms of CTE range from mood and behavioral changes to cognitive impairment, depression, and suicidality. So far, CTE cannot be diagnosed in vivo and thus specific diagnostic parameters for CTE need to be found, to observe and treat exposed athletes as early as possible. Promising blood-based biomarkers for CTE include total tau (tTau), hyperphosphorylated tau (pTau), neurofilament light protein (NF-L), glial fibrillary acidic protein (GFAP), amyloid-β40 (Aβ40), amyloid-β42 (Aβ42) and calcium-binding protein B (S100-B). Previous studies have found elevated levels of these biomarkers in subjects exposed to TBIs, whereas cerebrospinal fluid (CSF) levels of Aβ40 and Aβ42 were decreased in CTE subjects. Here, we investigated whether young AFPs already exhibit changes of these biomarker candidates during the course of a single active season. Methods Blood samples were drawn from n = 18 American Football Players before and after a full season and n = 18 male age-matched control subjects. The plasma titers of tTau, pTau, NF-L, GFAP, Aβ40, Aβ42 and S100-B were determined. Additionally, Apathy, Depression, and Health status as well as the concussion history and medical care were assessed and analyzed for correlations. Results Here we show, that the selected biomarker candidates for CTE do not change significantly during the seven-month period of a single active season of American Football in blood samples of AFPs compared to healthy controls. But interestingly, they exhibit generally elevated pTau titers. Furthermore, we found correlations of depression, quality-of-life, career length, training participation and training continuation with headache after concussion with various titers. Conclusion Our data indicates, that changes of CTE marker candidates either occur slowly over several active seasons of American Football or are exclusively found in CSF. Nevertheless, our results underline the importance of a long-term assessment of these biomarker candidates, which might be possible through repeated blood biomarker monitoring in exposed athletes in the future.

Background: Repetitive traumatic brain injuries in American football players (AFPs) can lead to the neurodegenerative disease chronic traumatic encephalopathy (CTE). Clinical symptoms of CTE range from mood and behavioral changes to cognitive impairment, depression, and suicidality. So far, CTE cannot be diagnosed in vivo and thus specific diagnostic parameters for CTE need to be found, to observe and treat exposed athletes as early as possible. Promising blood-based biomarkers for CTE include total tau (tTau), hyperphosphorylated tau (pTau), neurofilament light protein (NF-L), glial fibrillary acidic protein (GFAP), amyloid-β40 (Aβ40), amyloid-β42 (Aβ42) and calcium-binding protein B (S100-B). Previous studies have found elevated levels of these biomarkers in subjects exposed to TBIs, whereas cerebrospinal fluid (CSF) levels of Aβ40 and Aβ42 were decreased in CTE subjects. Here, we investigated whether young AFPs already exhibit changes of these biomarker candidates during the course of a single active season. Methods: Blood samples were drawn from n = 18 American Football Players before and after a full season and n = 18 male age-matched control subjects. The plasma titers of tTau, pTau, NF-L, GFAP, Aβ40, Aβ42 and S100-B were determined. Additionally, Apathy, Depression, and Health status as well as the concussion history and medical care were assessed and analyzed for correlations. Results: Here we show, that the selected biomarker candidates for CTE do not change significantly during the seven-month period of a single active season of American Football in blood samples of AFPs compared to healthy controls. But interestingly, they exhibit generally elevated pTau titers. Furthermore, we found correlations of depression, quality-of-life, career length, training participation and training continuation with headache after concussion with various titers. Conclusion: Our data indicates, that changes of CTE marker candidates either occur slowly over several active seasons of American Football or are exclusively found in CSF. Nevertheless, our results underline the importance of a long-term assessment of these biomarker candidates, which might be possible through repeated blood biomarker monitoring in exposed athletes in the future. [ABSTRACT FROM AUTHOR]

Exercising with elevated core temperatures may negatively affect autonomic nervous system (ANS) function. Additionally, longer training duration under higher core temperatures may augment these negative effects. This study evaluated the relationship between exercise training duration and 24 h ANS recovery and function at ≥37 °C, ≥38 °C and ≥39 °C core temperature thresholds in a sample of male Division I (D1) collegiate American football athletes. Fifty athletes were followed over their 25-week season. Using armband monitors (Warfighter MonitorTM, Tiger Tech Solutions, Inc., Miami, FL, USA), core temperature (°C) and 24 h post-exercise baseline heart rate (HR), HR recovery and heart rate variability (HRV) were measured. For HRV, two time-domain indices were measured: the root mean square of the standard deviation of the NN interval (rMSSD) and the standard deviation of the NN interval (SDNN). Linear regression models were performed to evaluate the associations between exercise training duration and ANS recovery (baseline HR and HRV) and function (HR recovery) at ≥37 °C, ≥38 °C and ≥39 °C core temperature thresholds. On average, the athletes were 21.3 (± 1.4) years old, weighed 103.0 (±20.2) kg and had a body fat percentage of 15.4% (±7.8%, 3.0% to 36.0%). The duration of training sessions was, on average, 161.1 (±40.6) min and they ranged from 90.1 to 339.6 min. Statistically significant associations between training duration and 24 h ANS recovery and function were observed at both the ≥38.0 °C (baseline HR: β = 0.10 ± 0.02, R2 = 0.26, p < 0.0000; HR recovery: β = −0.06 ± 0.02, R2 = 0.21, p = 0.0002; rMSSD: β = −0.11 ± 0.02, R2 = 0.24, p < 0.0000; and SDNN: β = −0.16 ± 0.04, R2 = 0.22, p < 0.0000) and ≥39.0 °C thresholds (β = 0.39 ± 0.05, R2 = 0.62, p < 0.0000; HR recovery: β = −0.26 ± 0.04, R2 = 0.52, p < 0.0000; rMSSD: β = −0.37 ± 0.05, R2 = 0.58, p < 0.0000; and SDNN: β = −0.67 ± 0.09, R2 = 0.59, p < 0.0000). With increasing core temperatures, increases in slope steepness and strengths of the associations were observed, indicating accelerated ANS deterioration. These findings demonstrate that exercise training under elevated core temperatures (≥38 °C) may negatively influence ANS recovery and function 24 h post exercise and progressively worsen. [ABSTRACT FROM AUTHOR]

Abstract Background Exposure to repetitive head impacts (RHI) in American football players can lead to cognitive impairment and dementia due to neurodegenerative disease, particularly chronic traumatic encephalopathy (CTE). The pathognomonic lesion of CTE consists of perivascular aggregates of hyper-phosphorylated tau in neurons at the depths of cortical sulci. However, it is unclear whether exposure to RHI accelerates amyloid-β (Aβ) plaque formation and increases the risk for Alzheimer’s disease (AD). Although the Aβ neuritic plaques characteristic of AD are observed in a minority of later-stage CTE cases, diffuse plaques are more common. This study examined whether former professional and college American football players, including those with cognitive impairment and dementia, have elevated neuritic Aβ plaque density, as measured by florbetapir PET. Regardless of cognitive and functional status, elevated levels of florbetapir uptake were not expected. Methods We examined 237 men ages 45–74, including 119 former professional (PRO) and 60 former college (COL) football players, with and without cognitive impairment and dementia, and 58 same-age men without a history of contact sports or TBI (unexposed; UE) and who denied cognitive or behavioral symptoms at telephone screening. Former players were categorized into four diagnostic groups: normal cognition, subjective memory impairment, mild cognitive impairment, and dementia. Positive florbetapir PET was defined by cortical-cerebellar average SUVR of ≥ 1.10. Multivariable linear regression and analysis of covariance (ANCOVA) compared florbetapir average SUVR across diagnostic and exposure groups. Multivariable logistic regression compared florbetapir positivity. Race, education, age, and APOE4 were covariates. Results There were no diagnostic group differences either in florbetapir average SUVR or the proportion of elevated florbetapir uptake. Average SUVR means also did not differ between exposure groups: PRO-COL (p = 0.94, 95% C.I. = [− 0.033, 0.025]), PRO-UE (p = 0.40, 95% C.I. = [− 0.010, 0.029]), COL-UE (p = 0.36, 95% CI = [0.0004, 0.039]). Florbetapir was not significantly associated with years of football exposure, cognition, or daily functioning. Conclusions Cognitive impairment in former American football players is not associated with PET imaging of neuritic Aβ plaque deposition. These findings are inconsistent with a neuropathological diagnosis of AD in individuals with substantial RHI exposure and have both clinical and medico-legal implications. Trial registration NCT02798185.

Abstract Background Neck injury is a common and often debilitating injury among athletes participating in American football. Limited data exists regarding neck injuries among elite athletes in the National Football League (NFL). To characterize the epidemiology of non-season ending, season-ending, and career-ending neck injuries in the NFL from 2016 through 2021. Methods Athletes who sustained neck injuries were identified using the NFL’s injured reserve (IR) list between the 2016 and 2021 seasons. Demographics and return to sport (RTS) data were collected. Available game footages were reviewed to identify the mechanism of injury (MOI). Injury incidence rates were calculated based on per team play basis. Results During the 6-year study period, 464 players (mean age 26.8 ± 3.2 years) were placed on the injury reserve list due to neck injuries. There were 285 defensive players and 179 offensive players injured (61.4 vs 38.6%, respectively, p

American football is characterized by its intense collision, which can induce serious injuries such as concussions and head trauma. Therefore, the evaluation of the safety of players is mandatory. In this study, we have developed a new finite element analysis model to evaluate the head kinematic response in American football. The novelty of our model is the incorporation of the effect of cervical muscle strength and pre-impact cervical muscle activation on head kinematics response. This model is based on the head-neck model extracted from the Total HUman Model for Safety (THUMS). The finite element analysis of the hit movement, which is frequently seen during the American football practices, is performed with four different cervical muscle conditions; (i) early pre-impact activation, (ii) late pre-impact activation, (iii) weak muscle strength, and (iv) No pre-impact activation. We also performed an experiment to measure head kinematics response and torso rotation in the hit movement of American football players by mouthguard sensors and video motion capture system for model validation. The four conditions parameter study shows that the time history of head angular velocity with pre-impact muscle activation is better agreement with our experimental results. Therefore, it is important to model the pre-impact cervical muscle activation in the finite element analysis for evaluating the head kinematic response accurately. We also found that higher cervical muscle strength and earlier cervical muscle activation decrease the head angular acceleration at 20-35 ms after the head collision. This suggests that, in the case of low-intensity head collision, strengthening cervical muscles and activating them before the head impact by anticipating the collision can reduce head angular acceleration.

For interscholastic athletes participating in outdoor sports, excessive heat can affect health, safety, and performance. Increasingly, many state high school associations have mandated weather-based activity modification and acclimatization policies, among other factors, to reduce exertional heat illnesses (EHIs) risk. Yet, modulating the practice schedule towards cooler times of the day, has not been widely used in interscholastic sports, in part because disruptions of predicable schedules can be difficult for athletic staff, athletes, and parents. We identified time-activity patterns of American football players in Georgia, U.S., to identify the variations in heat hazards and identify patterns that can be used for planning. Our dataset includes information on the date and time of practice, the activity type (game, scrimmage, practice), the wet bulb globe temperature (WBGT) and the occurrence of EHIs (i.e. heat exhaustion and heat syncope). We observed that practices tend to be held in the afternoon following the school day, while games/scrimmages mostly occur during the cooler evenings. These hotter afternoon conditions help explain the greater heat exhaustion / heat syncope illness rates observed for practices than for games or scrimmages. Our results show that shifting practices to the evening during the first four weeks of the season would reduce the likelihood of sessions exceeding 27.78oC WBGT by 32-55%. Adjusting practice schedules during the hottest weeks of the season is a way to reduce exposure to heat hazards and provide a predictable schedule for athletic staff, athletes and parents to follow. [ABSTRACT FROM AUTHOR]

Background: Exposure to repetitive head impacts (RHI) in American football players can lead to cognitive impairment and dementia due to neurodegenerative disease, particularly chronic traumatic encephalopathy (CTE). The pathognomonic lesion of CTE consists of perivascular aggregates of hyper-phosphorylated tau in neurons at the depths of cortical sulci. However, it is unclear whether exposure to RHI accelerates amyloid-β (Aβ) plaque formation and increases the risk for Alzheimer's disease (AD). Although the Aβ neuritic plaques characteristic of AD are observed in a minority of later-stage CTE cases, diffuse plaques are more common. This study examined whether former professional and college American football players, including those with cognitive impairment and dementia, have elevated neuritic Aβ plaque density, as measured by florbetapir PET. Regardless of cognitive and functional status, elevated levels of florbetapir uptake were not expected. Methods: We examined 237 men ages 45–74, including 119 former professional (PRO) and 60 former college (COL) football players, with and without cognitive impairment and dementia, and 58 same-age men without a history of contact sports or TBI (unexposed; UE) and who denied cognitive or behavioral symptoms at telephone screening. Former players were categorized into four diagnostic groups: normal cognition, subjective memory impairment, mild cognitive impairment, and dementia. Positive florbetapir PET was defined by cortical-cerebellar average SUVR of ≥ 1.10. Multivariable linear regression and analysis of covariance (ANCOVA) compared florbetapir average SUVR across diagnostic and exposure groups. Multivariable logistic regression compared florbetapir positivity. Race, education, age, and APOE4 were covariates. Results: There were no diagnostic group differences either in florbetapir average SUVR or the proportion of elevated florbetapir uptake. Average SUVR means also did not differ between exposure groups: PRO-COL (p = 0.94, 95% C.I. = [− 0.033, 0.025]), PRO-UE (p = 0.40, 95% C.I. = [− 0.010, 0.029]), COL-UE (p = 0.36, 95% CI = [0.0004, 0.039]). Florbetapir was not significantly associated with years of football exposure, cognition, or daily functioning. Conclusions: Cognitive impairment in former American football players is not associated with PET imaging of neuritic Aβ plaque deposition. These findings are inconsistent with a neuropathological diagnosis of AD in individuals with substantial RHI exposure and have both clinical and medico-legal implications. Trial registration: NCT02798185. [ABSTRACT FROM AUTHOR]

Background: British American Football (BAF) is a developing sport in the UK, with keen growth in the British Universities and Colleges Sport (BUCS) league. Participation in BAF carries risks and so to facilitate safe participation medical care services must be evaluated. Aims: To evaluate medical provision in BUCS American Football in the 2019–2020 season. Methods: An online survey tool was used to collect data from BUCS BAF teams in the 2019–2020 season. Thirty-one teams (from across England, Wales and Scotland) responded to questions on facilities, provision and procedures. Results: Almost 42% of teams had a regular team first aider who attended home games each week. Only 61.5% attended away games and 7.7% attended team training. Access to a first aider was not dependent upon division. Home games were more likely to be risk assessed and have an emergency action plan compared to away games. The majority of teams had access to automated external defibrillator (AED) within 100 m of the pitch, yet only 29% of staff were trained to use them. Almost 84% of teams reported carrying a designated fully charged phone (with signal). Prominent qualitative themes indicated were cost/funding as barriers to hiring qualified medical staff, lack of institutional support, unreliability of medical provision and inadequate facilities/preparation for games. Conclusions: These findings provide key information on the status of medical provision, facilities and protocols in BUCS BAF. Data reveals a lack of consistent medical personnel, particularly at training and away games, and training in emergency care. [ABSTRACT FROM AUTHOR]

Background: Neck injury is a common and often debilitating injury among athletes participating in American football. Limited data exists regarding neck injuries among elite athletes in the National Football League (NFL). To characterize the epidemiology of non-season ending, season-ending, and career-ending neck injuries in the NFL from 2016 through 2021. Methods: Athletes who sustained neck injuries were identified using the NFL's injured reserve (IR) list between the 2016 and 2021 seasons. Demographics and return to sport (RTS) data were collected. Available game footages were reviewed to identify the mechanism of injury (MOI). Injury incidence rates were calculated based on per team play basis. Results: During the 6-year study period, 464 players (mean age 26.8 ± 3.2 years) were placed on the injury reserve list due to neck injuries. There were 285 defensive players and 179 offensive players injured (61.4 vs 38.6%, respectively, p < 0.001). Defensive back was the most common position to sustain a neck injury (111 players, 23.9%). 407 players (87.7%) sustained non-season-ending injuries with a mean RTS at 9.2 ± 11.3 days. 36 players (7.8%) sustained season-ending injuries with a mean RTS at 378.6 ± 162.0 days. 21 players (4.5%) sustained career-ending injuries. The overall incidence of neck injuries was 23.5 per 10,000 team plays. The incidence of season-ending injuries and career-ending injuries were 1.82 and 1.06 per 10,000 team plays, respectively. There were 38 injuries with available footages for MOI assessment (23 non-season-ending, 9 season-ending, 6 career-ending). Head-to-head contact was seen in 15 injuries (39.5%), head-down tackling in 11 injuries (28.9%), direct extremity-to-head contact in 7 injuries (18.4%), and head-to-ground contact in 5 injuries (13.2%). There was no significant difference in age, position, or MOI among players sustaining non-season-ending, season-ending, and career-ending injuries. Conclusion: There is a high incidence of neck injuries among NFL athletes with predictable MOIs including head-to-head contact, head-down tackling, direct extremity-to-head contact, and head-to-ground contact. Defensive players were more likely to sustain neck injuries compared to offensive players. Defensive back was the most common position to sustain a neck injury. Level of evidence: III. [ABSTRACT FROM AUTHOR]

In recent years, the game of football has made a shift towards being more quantitative. With the advent of charting and tracking data, player evaluation is able to be studied from several different angles. In this paper, we build and refine two novel metrics: Bite Distance Under Expected (BDUE) and Ground Covered Over Expected (GCOE) for the evaluation of linebackers in the National Football League (NFL). Here, we show that these metrics are heavily correlated with each other, which demonstrates the trade-off linebackers have to make between being aggressive against the run and being effective when the opposing offense is using play-action. We also show that these metrics are more stable than those in the public space. Finally, we show how these metrics measure deception by opposing offenses. [ABSTRACT FROM AUTHOR]

The present study offers a descriptive history of the football grounds at Baylor from 1894 to 2014. The current review identifies important individuals and notable events that impacted the football facilities at Baylor. Moreover, the contextual factors influencing each period of change were recognized, and it was determined if Baylor's facilities followed the pattern of other regional peers. In the case of Baylor, football ultimately created social anchors for the institution and Waco because the increasing popularity and commercial interest in college football produced spectacles capable of providing a unique campus spirit. Next, the spectacle of football and spirit both established and improved alumni relationships and corresponded with interest in elevating the prestige of the university and city to attract students, visitors, and businesses to operate in the area. Finally, the construction of various Baylor football playing grounds produced significant media attention capable of boosting enrollments and recognition that Baylor was a major university. [ABSTRACT FROM AUTHOR]

In this study, to discuss the influence of concussion risk from the long-term use of American football helmets on collegiate teams, accident cases during the game are replicated based on game videos by simulations using whole-body numerical models and helmeted finite element human head models. The concussion risks caused by collisions were estimated using the mechanical parameters inside the skull obtained from finite element analyses. In the analyses, the different material properties of helmets identified by free-fall experiments using headform impactor-embedded helmets were used to represent brand-new and long-term-use helmets. After analyzing the five cases, it was observed that wearing a new helmet instead of a long-term-use one resulted in a reduction in the risk of concussion by 1 to 44%. More energy is attenuated by the deformation of the liners of the brand-new helmet, so the energy transferred to the head is smaller than that when wearing the long-term-use helmet. Thus, the long-term use of the helmet reduces its ability to protect the head.

Context: Recent data on exertional heat illness (EHI) in high school sports are limited yet warranted to identify specific settings with the highest risk of EHI. Objective: To describe the epidemiology of EHI in high school sports during the 2012/2013-2016/ 2017 academic years. Design: Descriptive epidemiology study. Setting: Aggregate injury and exposure data collected from athletic trainers working in high school sports in the United States. Patients or Other Participants: High school athletes during the 2012/2013-2016/2017 academic years. Intervention: High School Reporting Information Online surveillance system data from the 2012/2013-2016/2017 academic years were analyzed. Main Outcome Measures: EHI counts, rates per 10,000 athlete exposures (AEs), and distributions were examined by sport, event type, and US census region. EHI management strategies provided by athletic trainers were analyzed. Injury rate ratios with 95% confidence intervals (CIs) compared EHI rates. Results: Overall, 300 EHIs were reported for an overall rate of 0.13/10,000 AE (95% CI, 0.11 to 0.14). Of these, 44.3% occurred in American football preseason practices; 20.7% occurred in American football preseason practices with a registered air temperature ≥90°F and ≥1 hour into practice. The EHI rate was higher in American football than all other sports (0.52 vs 0.04/10,000 AE; injury rate ratio = 11.87; 95% CI, 9.22 to 15.27). However, girls' cross-country had the highest competition EHI rate (1.18/ 10,000 AE). The EHI rate was higher in the South US census region than all other US census regions (0.23 vs 0.08/10,000 AE; injury rate ratio = 2.96; 95% CI, 2.35 to 3.74). Common EHI management strategies included having medical staff on-site at the onset of EHI (92.7%), removing athlete from play (85.0%), and giving athlete fluids via the mouth (77.7%). Conclusions: American football continues to have the highest overall EHI rate although the high competition EHI rate in girls' cross-country merits additional examination. Regional differences in EHI incidence, coupled with sport-specific variations in management, may highlight the need for region- and sport-specific EHI prevention guidelines. [ABSTRACT FROM AUTHOR]

BackgroundEvidence shows relaxation techniques reactivate the parasympathetic nervous system (PNS) following physiological stressors such as exercise. As such, these techniques may be useful following exercise training of high intensity sports, like collegiate football.PurposeTo evaluate the impact of mindfulness and rest activities on PNS reactivation following training sessions, in a sample of Division-I collegiate, male football athletes.MethodsThis study employed a cross-sectional, pre-post experimental design among 38 football athletes. Following three training sessions, each separated by one week, athletes were exposed to three groups: mindfulness, rest, and no-intervention. Athletes in the mindfulness group laid supine in a darkened room, while performing 15 min of guided breathing and body scans. The rest group remained seated in a lighted room, performing 15 min of restful activities (e.g., talking). The no-intervention group was instructed to perform usual post-training activities (e.g., showering). Heart rate (HR), respiration rate (RR) and two HR variability (HRV) indices were measured via an armband monitor (Warfighter Monitor, Tiger Tech Solutions, Inc, Miami, FL) equipped with electrocardiographic and photoplethysmography capabilities. HRV indices included standard deviation of the N-N intervals (SDNN) and root mean square of successive RR interval differences (rMSSD). Within and between-group differences were determined via analysis of variance (ANOVA) and corrected for multiple comparisons familywise error.ResultsStatistically significant reductions in HR and RR were observed across all groups: −81.6, −66.4, −40.9 bpm and −31.7, −26.9, and −19.0 breaths⋅min−1, respectively. The mindfulness and rest groups exhibited a larger within-group reduction in HR and RR compared to the no-intervention group, p

Understanding the in-game demands placed on athletes may allow practitioners to design improved training protocols to prepare athletes for competitive demands. This study aimed to quantify the competitive movement demands of professional American football athletes and to determine any inter-positional differences that may exist. Player tracking data were collected from 2018 to 2020 regular season games of the National Football League. Distance, maximum velocity, high-velocity efforts and distance, and acceleration and deceleration efforts and distance were used to evaluate competitive movement demands. To determine position-specific demands, each player was classified by their designated position, and velocity data from competitive games were used to develop position-specific velocity thresholds. One-way ANOVA and post hoc Bonferroni statistical analysis were used to determine inter-positional difference. Significant (p < 0.05) positional differences were found for all load metrics with respect to competitive game demands. Generally, wide receivers and defensive backs had faster maximum velocities, higher distances, and more acceleration and deceleration efforts and distance than other positions. Linebackers accumulated the most high-velocity efforts and distance. Lineman had the lowest values for all assessed metrics. These findings may assist the performance staff in developing improved training and return-to-play protocols with the aim of improving player performance and mitigating injury. [ABSTRACT FROM AUTHOR]

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. 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. 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). 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. [ABSTRACT FROM AUTHOR]

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. 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). 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). 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. [ABSTRACT FROM AUTHOR]

Background: 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. Purpose: 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. Study Design: Cross-sectional study. Methods: 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. Results: 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. Conclusion: 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. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) tears are a high-frequency injury requiring a lengthy recovery in professional American football players. Concomitant pathology associated with ACL tears as identified on magnetic resonance imaging (MRI) is not well understood in these athletes. Purpose: To describe the MRI findings of concomitant injuries associated with ACL tears among athletes in the National Football League (NFL). Study Design: Cross-sectional study; Level of evidence, 3. Methods: Of 314 ACL injuries in NFL athletes from 2015 through 2019, 191 complete MRI scans from the time of primary ACL injury were identified and reviewed by 2 fellowship-trained musculoskeletal radiologists. Data were collected on ACL tear type and location, as well as presence and location of bone bruises, meniscal tears, articular cartilage pathology, and concomitant ligament pathology. Mechanism data from video review were linked with imaging data to assess association between injury mechanism (contact vs noncontact) and presence of concomitant pathology. Results: Bone bruises were evident in 94.8% of ACL tears in this cohort, most often in the lateral tibial plateau (81%). Meniscal, additional ligamentous, and/or cartilage injury was present in 89% of these knees. Meniscal tears were present in 70% of knees, lateral (59%) more than medial (41%). Additional ligamentous injury was present in 71% of all MRI scans, more often a grade 1/2 sprain (67%) rather than a grade 3 tear (33%), and most often involving the medial collateral ligament (MCL) (57%) and least often the posterior cruciate ligament (10%). Chondral damage was evident in 49% of all MRI scans, with ≥1 full-thickness defect in 25% of all MRI scans, most often lateral. Most (79%) ACL tears did not involve direct contact to the injured lower extremity. Direct contact injuries (21%) were more likely to have a concomitant MCL tear and/or medial patellofemoral ligament injury and less likely to have a medial meniscal tear. Conclusion: ACL tears were rarely isolated injuries in this cohort of professional American football athletes. Bone bruises were almost always present, and additional meniscal, ligamentous, and chondral injuries were also common. MRI findings varied by injury mechanism. [ABSTRACT FROM AUTHOR]

Background: Textbook knowledge and clinical dogma are often insufficient for effective evidence-based decision making when treating musculoskeletal injuries in American football players, given the variability in presentation and outcomes across different sports and different levels of competition. Key evidence can be drawn directly from high-quality published articles to make the appropriate decisions and recommendations for each athlete's unique situation. Purpose: To identify and analyze the 50 most cited articles related to football-related musculoskeletal injury to provide an efficient tool in the arsenal of trainees, researchers, and evidence-based practitioners alike. Study Design: Cross-sectional study. Methods: The ISI Web of Science and SCOPUS databases were queried for articles pertaining to musculoskeletal injury in American football. For each of the top 50 most cited articles, bibliometric elements were evaluated: citation count and density, decade of publication, journal, country, multiple publications by the same first author or senior author, article content (topic, injury area), and level of evidence (LOE). Results: The mean ± SD number of citations was 102.76 ± 37.11; the most cited article, with 227 citations, was "Syndesmotic Ankle Sprains" published in 1991 by Boytim et al. Several authors served as a first or senior author on >1 publication, including J.S. Torg (n = 6), J.P. Bradley (n = 4), and J.W. Powell (n = 4). The American Journal of Sports Medicine published the majority of the 50 most cited articles (n = 31). A total of 29 articles discussed lower extremity injuries, while only 4 discussed upper extremity injuries. The majority of the articles (n = 28) had an LOE of 4, with only 1 article having an LOE of 1. The articles with an LOE of 3 had the highest mean citation number (133.67 ± 55.23; F = 4.02; P =.05). Conclusion: The results of this study highlight the need for more prospective research surrounding the management of football-related injury. The low overall number of articles on upper extremity injury (n = 4) also highlights an area for further research. [ABSTRACT FROM AUTHOR]

Repetitive mild traumatic brain injury in American football players has garnered increasing public attention following reports of chronic traumatic encephalopathy, a progressive tauopathy. While the mechanisms underlying repetitive mild traumatic brain injury-induced neurodegeneration are unknown and antemortem diagnostic tests are not available, neuropathology studies suggest a pathogenic role for microvascular injury, specifically blood-brain barrier dysfunction. Thus, our main objective was to demonstrate the effectiveness of a modified dynamic contrast-enhanced MRI approach we have developed to detect impairments in brain microvascular function. To this end, we scanned 42 adult male amateur American football players and a control group comprising 27 athletes practicing a non-contact sport and 26 non-athletes. MRI scans were also performed in 51 patients with brain pathologies involving the blood-brain barrier, namely malignant brain tumours, ischaemic stroke and haemorrhagic traumatic contusion. Based on data from prolonged scans, we generated maps that visualized the permeability value for each brain voxel. Our permeability maps revealed an increase in slow blood-to-brain transport in a subset of amateur American football players, but not in sex- and age-matched controls. The increase in permeability was region specific (white matter, midbrain peduncles, red nucleus, temporal cortex) and correlated with changes in white matter, which were confirmed by diffusion tensor imaging. Additionally, increased permeability persisted for months, as seen in players who were scanned both on- and off-season. Examination of patients with brain pathologies revealed that slow tracer accumulation characterizes areas surrounding the core of injury, which frequently shows fast blood-to-brain transport. Next, we verified our method in two rodent models: rats and mice subjected to repeated mild closed-head impact injury, and rats with vascular injury inflicted by photothrombosis. In both models, slow blood-to-brain transport was observed, which correlated with neuropathological changes. Lastly, computational simulations and direct imaging of the transport of Evans blue-albumin complex in brains of rats subjected to recurrent seizures or focal cerebrovascular injury suggest that increased cellular transport underlies the observed slow blood-to-brain transport. Taken together, our findings suggest dynamic contrast-enhanced-MRI can be used to diagnose specific microvascular pathology after traumatic brain injury and other brain pathologies.

Point prediction of future record values based on sequences of previous lower or upper records is considered by means of the method of maximum product of spacings, where the underlying distribution is assumed to be a power function distribution and a Pareto distribution, respectively. Moreover, exact and approximate prediction intervals are discussed and compared with regard to their expected lengths and their percentages of coverage. The focus is on deriving explicit expressions in the point and interval prediction procedures. Predictions and forecasts are of interest, e.g., in sports analytics, which is gaining more and more attention in several sports disciplines. Previous works on forecasting athletic records have mainly been based on extreme value theory. The presented statistical prediction methods are exemplarily applied to data from various disciplines of athletics as well as to data from American football based on fantasy football points according to the points per reception scoring scheme. The results are discussed along with basic assumptions and the choice of underlying distributions.