Tight Ends Research Articles

Morphological and Performance Biomechanics Profiles of Draft Preparation American-Style Football Players

Background/Objectives: Using advanced methodologies may enhance athlete profiling. This study profiled morphological and laboratory-derived performance biomechanics by position of American-style football players training for the draft. Methods: Fifty-five players were categorized into three groups: Big (e.g., lineman; n = 17), Big–skill (e.g., tight end; n = 11), and Skill (e.g., receiver; n = 27). Body fat (BF%), lean body mass (LBM), and total body mass were measured using a bioelectrical impedance device. Running ground reaction force (GRF) and ground contact time (GCT) were obtained using an instrumented treadmill synchronized with a motion capture system. Dual uniaxial force plates captured countermovement jump height (CMJ-JH), normalized peak power (CMJ-NPP), and reactive strength. Asymmetry was calculated for running force, GCT, and CMJ eccentric and concentric impulse (IMP). MANOVA determined between-group differences, and radar plots for morphological and performance characteristics were created using Z-scores. Results: There was a between-group difference (F(26,80) = 5.70, p < 0.001; Wilk’s Λ = 0.123, partial η2 = 0.649). Fisher’s least squares difference post hoc analyses showed that participants in the Skill group had greater JH, CMJ-NPP, reactive strength, and running GRF values versus Big players but not Big–skill players (p < 0.05). Big athletes had greater BF%, LBM, total body mass, and GCT values than Skill and Big–skill athletes (p < 0.05). Big–skill players had greater GCT asymmetry than Skill and Big players (p < 0.05). Asymmetries in running forces, CMJ eccentric, and concentric IMP were not different (p > 0.05). Morphological and performance biomechanics differences are pronounced between Skill and Big players. Big–skill players possess characteristics from both groups. Laboratory-derived metrics offer precise values of running and jumping force strategies and body composition that can aid sports science researchers and practitioners in refining draft trainee profiles.

Position-Specific Differences in Speed Profiles Among National Football League Scouting Combine Participants.

Gillen, ZM. Position-specific differences in speed profiles among NFL scouting combine participants. J Strength Cond Res XX(X): 000-000, 2024-This study examined the relationships between speed profiles and athletic performance measurements from the National Football League (NFL) Scouting Combine, and position-specific differences in speed profiles. Subjects included NFL Scouting Combines participants with valid scores for the 40-yard dash, as well as the 10- and 20-yard splits of the 40-yard dash (n = 2,156). Subjects were divided into the following position groups: defensive backs (DBs, n = 421), defensive linemen (DL, n = 356), linebackers (LBs, n = 261), offensive linemen (OL, n = 354), running backs (RBs, n = 217), tight ends (TEs, n = 122), quarterbacks (QBs, n = 108), and wide receivers (WRs, n = 317). Performance measures included 40-yard dash time (with 10- and 20-yard split times), bench press repetitions to failure, vertical jump height, broad jump distance, pro-agility time, and L-cone drill time. The 40-yard dash and its splits calculated vmax, τ, and amax to reflect speed profiles. One-way analysis of variances examined position-related differences. Pearson's product moment correlation coefficients examined relationships between performance measures and speed profile variables. Skill positions (DB and WR) had the greatest vmax and amax, and lowest τ, followed by big skill positions (LB, RB, TE, QB), followed by DL, then OL with the lowest vmax and amax, and highest τ. For skill and big skill positions, vmax, τ, and amax exhibited greater relationships with combine measures, whereas OL generally had the lowest relationships. The position-specific differences in this study demonstrate potential areas of strength and weakness for certain positions. This may help guide strength and conditioning coaches desiring to improve position-specific speed and acceleration capabilities for American football players.

Muscle-to-Bone Ratio in NCAA Division I Collegiate Football Players by Position.

Dengel, DR, Studee, HR, Juckett, WT, Bosch, TA, Carbuhn, AF, Stanforth, PR, and Evanoff, NG. Muscle-to-bone ratio in NCAA Division I collegiate football players by position. J Strength Cond Res 38(9): 1607-1612, 2024-The purpose of this study was to compare the muscle-to-bone ratio (MBR) in National Collegiate Athletic Association Division I football players (collegiate football players [CFP]) to healthy, age-matched controls. In addition, we examined MBR in CFP by position. A total of 553 CFP and 261 controls had their total and regional lean mass (LM), fat mass (FM), and bone mineral content (BMC) determined by dual x-ray absorptiometry (DXA). College football players were categorized by positions defined as offensive linemen (OL), defensive linemen (DL), tight end, linebacker (LB), running back (RB), punter or kicker, quarterback (QB), defensive back (DB), and wide receiver (WR). There were significant differences between CFP and controls for total LM (80.1 ± 10.0 vs. 56.9 ± 7.8 kg), FM (22.2 ± 12.5 vs. 15.2 ± 7.1 kg), and BMC (4.3 ± 0.5 vs. 3.1 ± 0.5 kg). Although there were significant differences in body composition between CFP and controls, there was no significant differences in total MBR between CFP and controls (18.6 ± 1.4 vs. 18.8 ± 1.7). Regionally, CFP had significantly lower trunk MBR than controls (26.7 ± 2.7 vs. 28.7 ± 4.2), but no difference was seen in leg or arm MBR. Positional differences in CFP were noted as total MBR being significantly higher in DL (19.0 ± 1.4) than in DB (18.1 ± 1.3), WR (18.1 ± 1.3), and LB (18.2 ± 1.3). OL had a significantly higher total MBR (19.2 ± 1.3) than DB (18.1 ± 1.3), LB (18.2 ± 1.3), QB (18.1 ± 1.0), and WR (18.1 ± 1.3). In addition, RB had significantly higher total MBR (18.8 ± 1.3) than DB (18.1 ± 1.3) and WR (18.1 ± 1.3). This study may provide athletes and training staff with normative values when evaluating total and regional MBR with DXA.

Fantasy football points capture performance declines in National Football League offensive skill players following an ankle injury

BackgroundThe ankle is one of the anatomic sites most frequently injured in National Football League (NFL) players. Ankle injuries have previously been shown to have long-lasting negative impacts, and have been associated with impaired athletic performance. The aim of this study was to use fantasy football points as a metric to evaluate the impact of ankle injuries on NFL offensive skill player performance. MethodsAn open-access online database was used to identify NFL players who sustained ankle injuries from 2009 to 2020. Another public online database was used to determine fantasy points and other performance metrics for injured offensive skill players in the seasons before and after their ankle injury. Injured players were matched to a healthy control by position, age, and BMI. Paired T-tests were performed to evaluate performance metrics before and after the ankle injury. An ANCOVA was performed to assess the effect of return to play (RTP) time and injury type on fantasy performance. Results303 players with ankle injuries were included. Fantasy output, including average points per game (PPG) and total fantasy points accrued in one season, significantly decreased in the season following a player's ankle injury (p < 0.0001). In running backs, tight ends, and wide receivers, performance significantly decreased in every metric evaluated (p < 0.0001). In quarterbacks, there was no significant change in performance, except for a decrease in the number of games played (p = 0.0033) and in the number of interceptions thrown (p = 0.029). ConclusionAssessing fantasy football output revealed a decrease in player performance in the season following an ankle injury, especially in route-running players. These results can be used to inform injury prevention and rehabilitation practices in the NFL.

Decreased Concussion Incidence Following the Implementation of the Targeting Rules: An Updated Epidemiology of National Football League Concussions From 2017 to 2022.

The incidence of concussions in football, and the ensuing media attention, has garnered scientific investigation, prompted technological advances in protective gear, and altered the rules of the game, including the National Football League's (NFL) "Targeting" rule, which began in 2018, but the impact of these changes is unclear. This study aims to describe the epidemiology of concussions that occurred in five NFL seasons from the 2017-2018 season through the 2021-2022 season and characterize positional differences in rate and games missed. There was a significant decrease (p = 0.02) in total concussions between the 2017-2018 season (102 concussions) and the remaining four seasons (average of 73.80 concussions per year), accounting for a 38% decrease. Offensive and defensive units had decreased concussion rates and average games missed per concussion. Defensive backs (10.46 per 1,000 athlete exposures (AEs)) and tight ends (10.69 per 1,000 AEs) had the highest concussion rates, and the defensive line had the highest average games missed per concussion at 3.97. The introduction of the "Targeting" rule and other rule changes in the NFL in 2018 correlated with a decrease in total concussions per year, total games missed due to concussion, and average games missed per concussion. Offense and defense experienced similar reductions in concussion incidence and severity. Overall, the updated epidemiology of NFL concussions suggests that the incidence of concussions has decreased; however, players continue to experience concussions that require them to miss multiple games.

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

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

Multiple Ankle Injuries are Associated with an Increased Risk of Subsequent Concussion in National Football League Players

Category: Sports; Ankle Introduction/Purpose: Ankle injuries are among the most common musculoskeletal injuries in National Football League (NFL) players. Concussions are also concerningly frequent, especially given increasing post-mortem observations of chronic traumatic encephalopathy (CTE) in former NFL players. There is a gap in the literature regarding musculoskeletal risk factors for concussion, which is an avenue that must be explored to promote player safety. The purpose of this study is to observe if ankle injuries, especially multiple ankle injuries, are associated with an increased risk of subsequent concussion in NFL players. Methods: The public online database ProFootballReference.com was utilized to identify ankle injuries and concussions in NFL players, as well as demographic variables such as BMI and age. Multivariable logistic regression for subsequent concussion and ankle injury was performed, adjusting for BMI and player position. For descriptive statistics, unpaired T-tests with unequal variance were performed for continuous variables, including BMI and age. Chi-squared testing was performed for categorical variables, including player position, and whether the position was offensive (quarterback, running back, tight end, wide receiver, offensive line), defensive (defensive back, defensive line, linebacker), or on special teams (kicker, punter, long snapper). Results: 5,538 NFL players from the 2009-2010 to 2019-2020 seasons were included in the study. The mean BMI and age of the cohort was 31.06 (SD 4.55) and 24.41 (SD 3.63), respectively. Of these players, 941 had an ankle injury, 633 had a concussion, and 240 had both an ankle injury and a subsequent concussion. The adjusted odds ratio (aOR) for concussion following a single ankle injury was 0.90 (95% CI 0.72 – 1.14, p = 0.387), however, the aOR for concussion following multiple ankle injuries was 2.88 (95% CI 1.28 – 6.74, p = 0.015). The kicker position was determined to have the lowest risk for concussion following ankle injury, and the positions with comparatively greater risk are outlined in Table 1. Conclusion: Multiple ankle injuries were associated with an increased risk of a subsequent concussion by 188% after adjusting for BMI, player position, and offense/defense/special teams designation. Special teams as a group and by position (kicker, long snapper, punter) had the lowest risk of concussion following ankle injury, likely owing to the lower-impact nature of these positions. These findings can inform injury prevention practices in the National Football League.

Determining the True Incidence of Glenohumeral Instability Among Players in the National Football League: An Epidemiological Study of Non-Missed Time Shoulder Instability Injuries.

Shoulder instability encompasses a spectrum of glenohumeral pathology ranging from subluxation to dislocation. While dislocation frequently leads to removal from play, athletes are often able to play through subluxation. Previous research on glenohumeral instability among athletes has largely focused on missed-time injuries, which has likely disproportionately excluded subluxation injuries and underestimated the overall incidence of shoulder instability. To describe the epidemiology of shoulder instability injuries resulting in no missed time beyond the date of injury (non-missed time injuries) among athletes in the National Football League (NFL). Descriptive epidemiology study. The NFL's electronic medical record was retrospectively reviewed to identify non-missed time shoulder instability injuries during the 2015 through 2019 seasons. For each injury, player age, player position, shoulder laterality, instability type, instability direction, injury timing, injury setting, and injury mechanism were recorded. For injuries that occurred during games, incidence rates were calculated based on time during the season as well as player position. The influence of player position on instability direction was also investigated. Of the 546 shoulder instability injuries documented during the study period, 162 were non-missed time injuries. The majority of non-missed time injuries were subluxations (97.4%), occurred during games (70.7%), and resulted from a contact mechanism (91.2%). The overall incidence rate of game-related instability was 1.6 injuries per 100,000 player-plays and was highest during the postseason (3.5 per 100,000 player-plays). The greatest proportion of non-missed time injuries occurred in defensive secondary players (28.4%) and offensive linemen (19.8%), while kickers/punters and defensive secondary players had the highest game incidence rates (5.5 and 2.1 per 100,000 player-plays, respectively). In terms of direction, 54.3% of instability events were posterior, 31.9% anterior, 8.5% multidirectional, and 5.3% inferior. Instability events were most often anterior among linebackers and wide receivers (50% and 100%, respectively), while posterior instability was most common in defensive linemen (66.7%), defensive secondary players (58.6%), quarterbacks (100.0%), running backs (55.6%), and tight ends (75.0%). The majority of non-missed time shoulder instability injuries (97.4%) were subluxations, which were likely excluded from or underreported in previous shoulder instability studies due to the inherent difficulty of detecting and diagnosing shoulder subluxation.

Percentile Rankings and Position Differences for Absolute and Allometrically Scaled Performance Measures From the National Football League Scouting Combine.

Gillen, ZM. Percentile rankings and position differences for absolute and allometrically scaled performance measures from the National Football League scouting combine. J Strength Cond Res 37(12): e613-e624, 2023-This study aimed to provide percentile rankings for absolute and allometrically scaled performance measures for National Football League (NFL) Scouting Combine subjects and determine if allometric scaling affected position-specific differences in performance measures. Subjects included American football players ( n = 3,015) who participated in the NFL Scouting Combines between 2015 and 2019. Subjects were divided into position groups: defensive backs (DBs, n = 562), defensive linemen (DL, n = 498), linebackers (LBs, n = 395), offensive linemen (OL, n = 505), running backs (RBs, n = 303), tight ends (TEs, n = 165), quarterbacks (QBs, n = 165), and wide receivers (WRs, n = 422). Performance measures included 40-yd dash time (with 10- and 20-yd split times), bench press repetitions to failure, vertical jump height, broad jump distance, pro-agility time, and L-cone drill time. Descriptive statistics were computed for all performance metrics and allometrically scaled performance metrics. One-way analyses of variance tested for position group differences for absolute and allometrically scaled performance measures. Percentile rankings for absolute and allometrically scaled performance measures were determined. Position-specific differences for absolute performance measures indicated that DB and WR tended to be faster, jump higher and further, and have greater change-of-direction capabilities compared with LB, QB, RB, and TE, who scored better in these respects than OL and DL. Allometric scaling revealed that DL, LB, RB, and TE tended to have superior performance than DB and WR, with QB and OL having the poorest performance. This study provides percentile rankings and the equation and parameters by which coaches and practitioners may allometrically scale data for evaluations of normalized performance measures from the NFL Scouting Combine.

“Injury risk, concussions, race, and pay in the NFL”

We make two main contributions to the literature on work-related injury risk and economic outcomes in the context of American professional football. One is to examine an increasingly important specific injury, concussions, and compare its subsequent economic effects to those of other types of football injuries. Our other contribution is to study the role of race in understanding injury risk and severity and their resulting economic consequences, which has been overlooked in previous sports injury research. Using a specific position, tight ends, which allows conditioning on fine-grained relevant measures of player demographics, playing time, and performance, we find that whether a player continues to play NFL football from year to year is affected by type of injury and the player’s race. We calculate that the average ex post loss in annual compensation from a concussion is about 7%. Moreover, the effect of games missed due to concussion on continued employment is triple that of other injuries. Being white positively affects length of playing career independent of the measured productivity of the players involved. The racial gap in career length is approximately equal to the effect of an additional game missed from concussion. With respect to heterogeneity in the effects of injuries, both concussions and other injury types affect ex post economic outcomes equally for white and nonwhite players. Both injuries and race affect compensation solely through their effects on career length.

Poster 380: Decreased concussion incidence following revised contact rules; An updated epidemiology of NFL concussions from 2017-2022

Objectives: The incidence of concussions in football, and the media attention that followed, has garnered scientific investigation, prompted technological advances in protective gear, and altered the rules of the game, including the NFL’s “Targeting” rule, which began in 2018. In previously studied seasons, certain positions, such as offensive skill players, had higher rates of concussions while defensive secondary and offensive line players suffered the greatest number of concussions, but the severity of these concussions has not been reported. The advent of the “Targeting” rule has been shown to reduce concussions in collegiate football leagues, but its effect on NFL and professional-level players is unknown. The objectives of this retrospective study were to describe the epidemiology of concussions among professional football players in the NFL during the last five seasons, determine changes in incidence over the study period, and characterize positional differences in rate and games missed. Methods: The current study was a descriptive epidemiological study that retrospectively reviewed all concussions that occurred in the five NFL seasons from the 2017-2018 season through the 2021-2022 season that resulted in at least one game missed. Total concussions, total games missed due to concussion, and average games missed per concussion were extracted from publicly available injury reports and were cross-referenced with publicly available sources. Concussion rates were calculated per 1,000 athletic exposures (AEs). A sub-analysis was performed by year, game unit, position type, and game week. Results: In 1,216 regular season games in the five NFL seasons, there were a total of 368 concussions for a rate of 0.30 concussions per game and 7.04 concussions per 1,000 AEs. More concussions were concentrated in the last one-third of the regular season. There was a statically significant decrease (38%; p&lt;0.05) in total concussions between the 2017-2018 season (102 total concussions) and the four seasons between 2018-2019 and 2021-2022 (average of 73.8 concussions per year). During the five seasons, there were 1,014 games missed due to concussion, an average of 2.76 games missed per concussion, and 0.056 games missed due to concussion per 1,000 AEs. Following the 2017-2018 season, there was a 53% decrease in the total games missed due to concussion (Figure 1b) and a 38% decrease in the average games missed per concussion (Figure 1c). Descriptively, both offensive and defensive units had decreased concussion rates and average games missed per concussion in the four seasons after 2017 (Figure 2). Defensive backs (10.46 per 1,000 AEs) and tight ends (10.69 per 1,000 AEs) had the highest concussion rates. The defensive line had the highest average games missed per concussion at 3.97 (Table 1). Conclusions: The introduction of the “Targeting” rule in the NFL beginning in the 2018 season correlated with a decrease in total concussions per year, total games missed per concussion, and games missed per concussion. Both offensive and defensive units experienced similar reductions in concussion incidence and severity. Overall, the updated epidemiology of NFL concussions suggests that efforts to protect professional football players from concussions have been successful, however, players continue to experience concussions that require them to miss multiple games. [Table: see text]

Profile of Caloric Needs of Football Athletes by Position in Football School

The purpose of writing this article is to find out and recommend calorie and energy profiles in shaping the stamina of football athletes in football schools. The search for this article uses a qualitative descriptive method through literature studies sourced from references that are willing to be studied conceptually and inferred from the results of the discussion. The results of this study show that the average calorie needs in the Defensive Lineman position requires as much as 6,100 - 6,400 kilo calories, in the Offensive Lineman position it requires as much as 6,200-6,500 kilo calories, in the Running Back position it requires as much as 5,700-6,000 kilo calories, in the Tight End position it requires as much as 6,000-6,300 kilo calories, the Linebacker needs as many as 5,900-6,200 kilo calories, and, in the Quarterback position, it needs as many as 5,200-5,400 kilo calories. Furthermore, the fulfillment of balanced nutrition for SSB football athletes that must be applied conditionally and proportionally is as follows Calories for football athletes are needed at 3542-4693 kilo calories per athlete per day, carbohydrate fulfillment for athletes as much as 531703 grams per athlete per day, protein fulfillment as much as 132-175 grams per athlete pr day, and fat fulfillment is needed at 118-156 grams per athlete per day.

Objective Measures of Strain and Subjective Muscle Soreness Differ Between Positional Groups and Season Phases in American College Football.

To assess objective strain and subjective muscle soreness in "Bigs" (offensive and defensive line), "Combos" (tight ends, quarterbacks, line backers, and running backs), and "Skills" (wide receivers and defensive backs) in American college football players during off-season, fall camp, and in-season phases. Twenty-three male players were assessed once weekly (3-wk off-season, 4-wk fall camp, and 3-wk in-season) for hydroperoxides (free oxygen radical test [FORT]), antioxidant capacity (free oxygen radical defense test [FORD]), oxidative stress index (OSI), countermovement-jump flight time, Reactive Strength Index (RSI) modified, and subjective soreness. Linear mixed models analyzed the effect of a 2-within-subject-SD change between predictor and dependent variables. Compared to fall camp and in-season phases, off-season FORT (P ≤ .001 and <.001), FORD (P ≤ .001 and <.001), OSI (P ≤ .001 and <.001), flight time (P ≤ .001 and <.001), RSI modified (P ≤ .001 and <.001), and soreness (P ≤ .001 and <.001) were higher for "Bigs," whereas FORT (P ≤ .001 and <.001) and OSI (P = .02 and <.001) were lower for "Combos." FORT was higher for "Bigs" compared to "Combos" in all phases (P ≤ .001, .02, and .01). FORD was higher for "Skills" compared with "Bigs" in off-season (P = .02) and "Combos" in-season (P = .01). OSI was higher for "Bigs" compared with "Combos" (P ≤ .001) and "Skills" (P = .01) during off-season and to "Combos" in-season (P ≤ .001). Flight time was higher for "Skills" in fall camp compared with "Bigs" (P = .04) and to "Combos" in-season (P = .01). RSI modified was higher for "Skills" during off-season compared with "Bigs" (P = .02) and "Combos" during fall camp (P = .03), and in-season (P = .03). Off-season American college football training resulted in higher objective strain and subjective muscle soreness in "Bigs" compared with fall camp and during in-season compared with "Combos" and "Skills" players.

Player Position and Labral Tear Location and Size in NCAA Division I Football Players Undergoing Arthroscopic Surgery.

Shoulder instability attributed to glenoid labral tears is common among National Collegiate Athletic Association (NCAA) football players. Certain repetitive activities by player position may contribute to instability. To compare the location of labral tears among player positions in NCAA Division I football. Cross-sectional study. We conducted a review of football players who underwent shoulder labral repair between 2000 and 2020 at a single institution. Inclusion criteria were NCAA Division I level, diagnosis of shoulder instability, and labral tear requiring arthroscopic repair. Exclusion criteria were prior surgery on injured shoulder and incomplete medical records. Players were divided into 3 groups: line players (offensive and defensive linemen, defensive end), skill players (defensive back, wide receiver, running back, and quarterback), and hybrid players (linebacker and tight end). Labral tear location and size were recorded using the clockface method and categorized into 6 zones: superior, anterosuperior, anteroinferior, inferior, posteroinferior, and posterosuperior. Comparison of variables was performed using chi-square test or Fisher exact test (categorical) and 1-way analysis of variance or Kruskal-Wallis H test (continuous). The Spearman rank-order correlation was used to assess relationships between continuous data. Of the 53 included players, 37 (70%) were offensive linemen, defensive linemen, and linebackers. There were 29 line players, 11 skill players, and 13 hybrid players. Line players represented 55% of included players and had the most total labral tears as compared with all groups. Hybrid players had a significantly higher percentage of posterosuperior tears than line players (92% vs 52%; P = .015) and skill players (92% vs 27%; P = .002). Skill players had a significantly higher percentage of anterior tears at 3:00-4:00 and 5:00-6:00 when compared with hybrid players (82% vs 15%, P = .003; 82% vs 31%, P = .012, respectively). There was a positive correlation between labral tear size and number of suture anchors (0; P = .010). In this study of NCAA Division I football players, skill players had a higher proportion of anteroinferior labral tears, and hybrid players had a higher proportion of posterosuperior labral tears.

Effect of Player Position on Serum Biomarkers during Participation in a Season of Collegiate Football.

This prospective cohort study examined the relationship between a panel of four serum proteomic biomarkers (glial fibrillary acidic protein [GFAP], ubiquitin C-terminal hydrolase-L1 [UCH-L1], total Tau, and neurofilament light chain polypeptide [NF-L]) in 52 players from two different cohorts of male collegiate student football athletes from two different competitive seasons of Division I National Collegiate Athletic Association Football Bowl Subdivision. This study evaluated changes in biomarker concentrations (as indicators of brain injury) over the course of the playing season (pre- and post-season) and also assessed biomarker concentrations by player position using two different published classification systems. Player positions were divided into: 1) speed (quarterbacks, running backs, halfbacks, fullbacks, wide receivers, tight ends, defensive backs, safety, and linebackers) versus non-speed (offensive and defensive linemen), and 2) "Profile 1" (low frequency/high strain magnitudes positions including quarterbacks, wide receivers, and defensive backs), "Profile 2" (mid-range impact frequency and strain positions including linebackers, running backs, and tight ends), and "Profile 3" (high frequency/low strains positions including defensive and offensive linemen). There were significant increases in GFAP 39.3 to 45.6 pg/mL and NF-L 3.5 to 5.4 pg/mL over the course of the season (p < 0.001) despite only five players being diagnosed with concussion. UCH-L1 decreased significantly, and Tau was not significantly different. In both the pre- and post-season blood samples Tau and NF-L concentrations were significantly higher in speed versus non-speed positions. Concentrations of GFAP, Tau, and NF-L increased incrementally from "Profile 3," to "Profile 2" to "Profile 1" in the post-season. UCH-L1 did not. GFAP increased (by Profiles 3, 2, 1) from 42.4 to 49.6 to 78.2, respectively (p = 0.051). Tau increased from 0.37 to 0.61 to 0.67, respectively (p = 0.024). NF-L increased from 3.5 to 4.9 to 8.2, respectively (p < 0.001). Although GFAP and Tau showed similar patterns of elevations by profile in the pre-season samples they were not statistically significant. Only NF-L showed significant differences between profiles 2.7 to 3.1 to 4.2 in the pre-season (p = 0.042). GFAP, Tau, and NF-L concentrations were significantly associated with different playing positions with the highest concentrations in speed and "Profile 1" positions and the lowest concentrations were in non-speed and "Profile 3" positions. Blood-based biomarkers (GFAP, Tau, NF-L) provide an additional layer of injury quantification that could contribute to a better understanding of the risks of playing different positions.

Association Between Head Impact Biomechanics and Physical Load in College Football.

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

Poster 150: Defining the True Incidence of Glenohumeral Instability Among American Football Players: an Epidemiological Study of Non-missed-time Shoulder Instability Injuries in the National Football League

Objectives:Shoulder instability is a common injury among contact- and collision-sport athletes that encompasses a spectrum of glenohumeral pathology ranging from subluxation to dislocation. While glenohumeral dislocation frequently leads to removal from play, athletes are often able to play through glenohumeral subluxation. Previous research on glenohumeral instability among athletes has largely focused on missed-time injuries only, which has likely disproportionately excluded subluxation injuries and underestimated the overall incidence of shoulder instability. The objective of this study is to describe the epidemiology of shoulder instability injuries not resulting in missed time among professional athletes in the National Football League (NFL) during the 2015 through 2019 seasons.Methods:The NFL’s Electronic Medical Record was retrospectively reviewed to identify shoulder instability injuries that did not result in missed time during the 2015 through 2019 seasons. For each injury, player age, player position, shoulder laterality, instability type, instability direction, injury timing, injury setting, and injury mechanism were recorded. For injuries that occurred during games, incidence rates were calculated based on timing during the season as well as player position. The influence of player position on instability direction was also investigated.Results:During the 2015 through 2019 seasons, 546 shoulder instability injuries were documented in the NFL’s Electronic Medical Record. Of these, 162 (29.7%) did not result in missed time beyond the date of injury. The majority of non-missed-time injuries were subluxations (97.4%), occurred during games (70.7%), and resulted from a contact mechanism (91.2%). The overall incidence rate of game-related instability was 1.6 injuries per 100,000 player-plays and was highest during the postseason (3.5 per 100,000 player-plays). With respect to player position, the greatest number of non-missed-time instability injuries occurred in defensive secondary (28.4%) and offensive linemen (19.8%), while kickers/punters and defensive secondary had the highest game incidence rates (5.5 and 2.1 per 100,000 player-plays, respectively). In terms of direction, 54.3% of instability events were posterior, 31.9% anterior, 8.5% multidirectional, and 5.3% inferior. Instability events were most often anterior among linebackers and wide receivers (50% and 100%, respectively), while posterior instability was most common for defensive linemen (66.7%), defensive secondary (58.6%), quarterbacks (100.0%), running backs (55.6%), and tight ends (75.0%).Conclusions:Shoulder instability injuries that do not result in missed time beyond the date of injury are much more common among collision-sport athletes than previously thought, accounting for approximately 30% of all instability events in the NFL. The majority of these injuries are posterior subluxations, though instability direction appears to vary by player position. This study highlights the diverse nature of shoulder instability injuries and underscores the need for increased surveillance among collision-sport athletes, as even subluxations can result in significant damage to the capsulolabral complex.TABLE 1.Non-missed-time shoulder instability injuries by year from 2015 through 2019a.TABLE 2.Incidence of game-related non-missed-time shoulder instability injuries by season from 2015 through 2019.TABLE 3.Incidence of game-related non-missed-time shoulder instability injuries by player roster positiona from 2015 through 2019b.Figure 1.Distribution of non-missed-time shoulder instability direction by player roster position from 2015 through 2019.

Return to Full Participation Following Concussion in the National Football League, 2015 Through 2020.

Quantify days missed, games missed, injury burden, and time to return to full participation (RTFP) among National Football League (NFL) players who sustained a concussion. Retrospective cohort study. 2015 through 2020 NFL seasons. National Football League players diagnosed with a concussion from 2015 to 2020. National Football League-mandated graduated RTFP protocol. Days missed, games missed, burden, and time to RTFP, overall and by position. An annual average of 3639 player-days of participation and 255 games were missed across NFL because of concussion. Concussed players missed a median of 9 days (mean = 15.0), a relatively stable metric over 6 years, with slight variation by position. Offensive linemen, tight ends, running backs, and linebackers missed the most days per concussion; defensive secondary, offensive linemen, and wide receivers sustained the highest injury burden. Postconcussion, 59% of players missed one or more scheduled games. Among players concussed in a Sunday game, 38% played in a Sunday game one week later. The 9-day median time missed post-concussion may be related to emphasis on graduated phase-based concussion management. No concussed player returned to competition on the day of injury, and less than 40% participated in games the following week. Further work is needed to better understand characteristics of concussions that take longer to return and movement through stages of return.

The Impact of 12 Weeks of Training on Body Composition and Blood Pressure in NCAA football players Division II

Football is one of the most popular sports in North America. Because of different position-specific demands, football players require a different skill set highly dependent on their anthropometric characteristics and body composition. Therefore, the goal of the study was to identify the impact of an off-season training program among NCAA football players Division II of different positions on body mass index (BMI), percentage of muscle, and fat. Football players (N=68) were tested at the beginning of the off-season training and at the end of this training period. Percentage of fat and muscle mass, and BMI of players from eight positions (quarterback, running back, wide receiver, tight end, offensive line, defensive line, linebacker, and defensive back) were assessed. At the beginning of the off-season, BMI of the offensive line and the defensive line was higher than all other positions; however, only the offensive line had a higher body fat percentage and lower muscle mass percentage when compared to the other positions, except the defensive line (p&lt;0.05). There was an increase in the percentage of muscle mass overall (p&lt;0.05) and no difference in the percentage of fat (p=0.053) at the end of the off-season when compared to the beginning. When stratified in positions, the percentage of muscle increased in quarterback, wide receiver, linebacker, and defensive back, whereas the percentage of fat decreased in running back, wide receiver, linebacker, and defensive back (p&lt;0.05). Thus, the training program applied during the off-season improves body composition and reflects on the performance enhancement of NCAA football players Division II.

Contact and slip behaviors of main cable of the long-span suspension bridge

In order to ensure the anti-slip safety of main cable in the main saddle of long-span suspension bridge, contact and slip behaviors of main cable of the long-span suspension bridge were investigated in this study. Mechanical characteristics of main cable were explored according to statics theory. Finite element models were established to analyze effects of pretension, applied load and coefficient of friction on stress distributions, contact statuses and slip characteristics of strands/wires along arc contact paths in the saddle. A friction and slip test rig was developed to explore slip characteristics between strands and saddle in order to validate finite element models. The results show that there are micro slips at both ends and adhesion in the central region along the arc contact paths between strand/steel wire and saddle in all cases. The micro slips decrease with increasing pretension and coefficient of friction, and increase with increasing applied load. The strand and steel wire at the lower layer exhibit the easier gross slip and the larger difference between axial stresses at both ends as compared to those at the upper layer. The axial stress difference of strand increases with increasing pretension and coefficient of friction, respectively. The friction and slip tests show that the upper layer strand exhibits the larger maximum displacement amplitude corresponding to gross slip, and the tangential force increment of strand along the arc contact path decrease in the order: tight end, central location and loose end, which validates finite element models.