American Football Players Research Articles

Symbolic Use of Language as a Means to Demonstrate Accommodation

This paper reports on how a prominent American football player, Joe Burrow, from the state of Ohio adopts the Cajun English spelling system used in Louisiana, a southern state in the U.S., in a symbolic and innovative way during his short stay there when he relocated to Louisiana from Ohio for the final two years of his college career. In previous studies of language attitudes toward English dialects in the U.S., Michiganders evaluated the English used in the Great Lakes area (including Ohio) as the best variety while judging the English spoken in the South (including Louisiana) as the worst. Although Burrow may not carry such language attitude, it is implicitly demonstrated in media coverage related to his college football career. Despite the harsh folk evaluation and rather negative portrait from the media of the Southern U.S. English, Burrow’s accommodation to the Cajun English spelling was a means to express his gratitude to the state of Louisiana and resonated through the U.S. in various ways.

Rehabilitation of Persistent Neurocognitive Deficits Following Sports-Related Concussion in an Amateur Football Athlete: Case Study

Demonstrate neurocognitive improvements in an inactive, amateur football athlete following a functional neurology approach to multimodal neurorehabilitation. American Football has been reported to have one of the highest incidences of concussion in all contact sports. Given the high rate of concussive blows during play, the investigation of treatment modalities is warranted. This case study presents a 23-year-old male amateur football player who has sustained 3 diagnosed concussions with additional suspected concussions throughout his time participating in football. In addition, his symptoms persisted years after ceasing participation in all contact sports. The athlete was prescribed 10 treatment sessions over 5 consecutive days at an outpatient neurorehabilitation center specializing in functional neurology. The C3Logix neurocognitive assessment and Graded Symptom Checklist were utilized on intake and discharge. Multimodal treatment interventions included transcranial photobiomodulation, non-invasive neuromodulation of the lingual branch of the trigeminal nerve, neuromuscular reeducation of the limbs bilaterally, hand-eye coordination training, vestibular rehabilitation utilizing a three-axis whole-body off-axis rotational device, and cognitive training. On intake, composite symptom score was reported as 10/162, Trails Making Test Part A was 20.8 seconds, Part B was 41.9 seconds, Digit Symbol Matching score was 53, Simple Reaction Time was 277 milliseconds, and Choice Reaction Time was 412 milliseconds. On discharge, the patient experienced a 70% in self-reported symptoms, Trails A improved to 14.8 seconds (+29%), Trails B improved to 30.3 seconds (+28%), Simple Reaction Time was 248 milliseconds (10% faster), and Choice Reaction Time was 340 milliseconds (17% faster). The present case study demonstrates a meaningful improvement in symptoms and neurocognitive performance of a patient with multiple sports-related concussions. Therefore, the Press suggest further investigation into a functional neurology approach to multi-modal, intensive care to improve neurocognitive impairment in athletes that sustained concussions participating in footballs.

Impact of Playing Surface on Concussion Symptoms in Young American Football Players

To identify differences in symptoms following sports-related concussion (SRC) on natural grass vs artificial turf in youth and adolescent football players. There is continued interest in reducing risk of SRC in football, with playing surface being one potentially modifiable factor. It is estimated that 15-30% of concussions result from helmet-to-ground contact, and some studies have suggested a higher incidence of SRC on grass in competitive contact sports compared to turf. To our knowledge, our study is the first to investigate reported post-concussive symptoms after SRC as they relate to playing surface. Data were prospectively collected from the North Texas Concussion Registry (ConTex), a longitudinal multi-institutional concussion database. We selected male football players between the ages of 10 and 24 who sustained a helmet-to-ground SRC (GCS 13-15) on either grass or turf. Pre-injury information and post-concussive symptoms (Graded Symptom Checklist from the SCAT-5) were collected at an initial in-person visit within 2 weeks of injury and via electronic follow up at 3 months. Fifty-eight participants were included (grass = 32, turf = 26), and groups were similar in age (p = 0.089), time since injury (p = 0.500), history of headache (χ2 = 0.167), and prior history of concussion (χ2 = 0.868). Athletes who sustained SRC on grass reported significantly higher scores on the Graded Symptom Checklist (p = 0.018, mean 26.0 vs 11.4) and higher numbers of distinct symptoms (p = 0.013, mean 10.2 vs 5.5) compared to those who sustained SRC on turf. Symptoms that were rated significantly higher after SRC on grass included headache (p = 0.010), phonophobia (p = 0.014), dizziness (p = 0.001), fatigue (p = 0.021), blurred vision (p = 0.001), feeling "in a fog" (p = 0.014), difficulty remembering (p = 0.004), and feeling emotional (p = 0.041). Youth and adolescent football players who sustain SRC on grass report higher post-concussive symptom severity and burden. Elucidating differential effects of SRC on grass vs turf is important, as competitive playing surface is a modifiable risk factor.

Пулсометрични критерии за класификация на тренировъчните натоварвания

Measuring heart rate gives us the opportunity to make the best analysis of the behaviour of the cardiac system during physical activity and aids us to decide for the ideal training programs a performer must undergo. The aim for the investigation was to draw observant conclusions which would aid us in choosing the activities in said program, as the results portrayed the body’s response to the different intensities of the physical tests. The pulsometric criteria for the classification of the training overloads among amateur runners and football players were used.

Age at League Entry and Early All-Cause Mortality among National Football League Players

Background: A growing body of research suggests that American football players are exposed to higher cumulative head impact risk as competition level rises. Related literature finds that head impacts absorbed by youth, adolescent, and emerging adult players are associated with elevated risk of long-term health problems (e.g., neurodegenerative disease onset). Most National Football League (NFL) players enter the League as emerging adults (18–24 years old), a period of continued cognitive and overall physical development. However, no prior research has studied the effect of age-at-entry on long-term NFL player health. Hypothesis/Purpose: This study assesses whether early NFL player age-at-entry is associated with increased risk of early all-cause mortality, controlling for player position, BMI, year-of-entry, birth year, and NFL Draft round (expected ability upon League entry). Study Design: This retrospective cohort study included 9049 players who entered the NFL from 1970–2017 and subsequently played at least one game. The variables whether deceased, age-at-death, age-at-entry, and controls were collected from Pro Football Reference website, a leading data site for American football that has been used extensively in the literature. Data collection began on 13 July 2017, and follow-up ended on 1 July 2018. Statistical analysis was performed from 10 March 2020 to 3 August 2020. Data was validated by checking a large sub-sample of data points against alternative sources such as NFL.com and NFLsavant.com. Methods: Cox proportional hazards regression models were used to examine variation in death hazard by NFL player age-at-entry, conditional upon a full set of controls. Results: Conditional on controls, Cox regression results indicate that a one-year increase in age-at-entry was significantly associated with a 14% decreased hazard-of-death (H.R., 0.86; 95% CI, 0.74–0.98). Among relatively young entering players, the increased hazard appears to be concentrated in the first quartile of players by age at League entry (20.2 to 22.3 years). Players not in this quartile exhibited a decreased hazard-of-death (H.R., 0.74; 95% CI, 0.57–0.97) compared with players who entered at a relatively young (first quartile) age. Conclusion: An earlier age-at-entry is associated with an increased hazard-of-death among NFL players. Currently, the NFL regulates age-at-entry only indirectly by requiring players to be 3 years removed from high school before becoming NFL Draft-eligible. Implementing a minimum age at entry for NFL players of 22 years and 4 months at beginning of season is expected to result in reduced mortality. What is known about this subject? There are no prior studies on the effects of NFL player age-at-entry on early mortality risk. What this study adds to existing knowledge: This study determines whether entering the NFL at an age of physical and physiological development is related to early mortality risk.

Sports Level and the Personality of American Football Players in Poland.

Research on personality in sport is very popular as it allows prediction of the behavior of players in the starting situation. Hence, verifications of players due to their sports level may turn out to be crucial. Due to the dynamic development of American football in Poland, we undertook research to verify the relationship between the sports level and the personality of these players. The Big Five personality study that we carried out involved players aged from 20 to 29—the representatives of American football clubs in Poland (N = 140) from three league games levels: LFA 1 (n = 75), LFA 2 (n = 40), and LFA 9 (n = 25). The NEO-FFI personality questionnaire was used as a research tool. The players from the top-level games were characterized by their openness to experience, the level of which decreases along with the decrease in the players’ sports levels. The differences in openness to experience were revealed, first of all, in divergent thinking and creativity. It was ascertained that openness to experience is a characteristic personality trait for American football players in Poland. Therefore, systematic conduct of personality tests among American football players in Poland, in the process of selecting candidates for the highest levels of football competition, would be recommended. This might significantly affect the development of the sports level of this discipline in Poland. The obtained results of research on personality may, moreover, prove to be useful in selecting players and improving the predictions of important sports behaviors in American football in Poland.

Position-Specific Physical Workload Intensities in American Collegiate Football Training.

MamonJr, MA, Olthof, SBH, Burns, GT, Lepley, AS, Kozloff, KM, and Zernicke, RF. Position-specific physical workload intensities in American collegiate football training. J Strength Cond Res 36(2): 420-426, 2022-Quantifying player training loads allows football coaching staff to make informed adjustments to the volume and intensity of training. Physical workload intensity in American football practices have not been extensively quantified. The current study examined physical workload intensities across positions in American collegiate football during training. Data from player tracking technology (Catapult Vector) were collected from 72 American football players (National Collegiate Athletic Association Division I) during in-season practices. Players were involved in individualized skill (indy), team playbook (team), and special team (ST) drills during practice and analyzed for their specialist offensive or defensive role (e.g., linebacker or wide receiver). Player running (i.e., high-speed running and sprint) and accelerations (i.e., high-intensity PlayerLoad and high-intensity inertial movement analysis) per minute were of interest. Drill type and practice day had significant effects on all workload intensity metrics (p < 0.01), but not position. Greater running intensities were seen in ST drills compared with other drill types. Tuesday practice sessions had greater overall intensities compared with other days. Interaction effect of position and drill type was significant (p < 0.001) for all intensity metrics, indicating that position groups exhibited unique workload responses to the drill types. Drill type and practice day interaction effect was significant for all intensity metrics (p < 0.01). The findings may be informative for coaches to tailor physical workloads of practice drills for positional roles in preparation for games and practices. Player tracking technology can add value for strength and conditioning coaches to adjust training programs based on position-specific on-field demands of players.

Biomonitoring of urinary metals in athletes according to particulate matter air pollution before and after exercise.

Exposure to air pollution during physical exercise is a health issue because fine particulate matter (dimension < 10 μm; PM10) includes several inhalable toxic metals. Body metal changes in athletes according to air pollution are poorly known. Urinary concentrations of 15 metals: beryllium (Be9), aluminum (Al27), vanadium (V51), chromium (Cr51 + Cr52), manganese (Mn55), cobalt (Co59), nickel (Ni61), copper (Cu63), zinc (Zn61), arsenic (As75), selenium (Se82), cadmium (Cd111 + Cd112), thallium (Tl125), lead (Pb207), and uranium (U238) were measured before and after ten 2-h training sessions in 8 non-professional Italian American-football players (18–28 years old, body mass index 24.2–33.6 kg/m2). Collectively, post-training sessions, urinary concentrations of As, Cd, Co, Cu, Mn, Ni, Pb, Se, Tl, and Zn were higher than pre-training sessions; Al, Be, Cr, and U did not change; conversely, V decreased. Subdividing training sessions according to air PM10 levels: low (< 20 μg/m3), medium (20–40 μg/m3), and high (> 40 μg/m3), pre-session and post-session urinary concentrations of Be, Cd, Cu, and Tl were significantly higher (p < 0.05) in more polluted days, whereas V concentrations were lower (p < 0.001). All the remaining metals were unaffected. We first showed that PM10 levels modulate urinary excretion of some toxic metals suggesting an effect of air pollution. The effects of toxic metals inhaled by athletes exercising in polluted air need further studies.

Neuropsychological test performance in former college and professional American football players

AbstractBackgroundRepetitive head impacts from American football have been associated with long‐term cognitive symptoms. The late neuropsychological profiles of this population is not well‐characterized. Research has relied on retrospective informant reports and/or has been small samples of former professional players. We describe objective neuropsychological test performance in former college and professional American football players.MethodsMale (45‐74 years) former National Football League (n=107) and college football players (n=59) from the DIAGNOSE‐CTE Research Project completed a neuropsychological test battery, Functional Activities Questionnaire (FAQ) and Quick Dementia Rating Scale (QDRS). Neuropsychological test scores were converted to T‐scores using age, sex, and/or education‐adjusted normative data. T‐scores&lt;35 defined impairment. Participants were enrolled across the spectrum of symptom severity (asymptomatic to dementia). Individuals without decisional capacity were excluded. Participants with missing data (n=4) and who scored &lt;45 on Test of Memory Malingering Trial 2 (n=10) were excluded.Results108 (65.1%) identified as White and 53 (31.9%) as Black. Mean education years was 16.76 (SD=1.48). Fourteen (8.4%) and 6 (3.6%) reported diagnostic history of ADHD and learning disability, respectively. Average Montreal Cognitive Assessment score was 24.96 (SD=3.17); 85 (51.2%) scored &lt;26. Impairment rates were highest for learning and episodic memory. On Neuropsychological Assessment Battery List Learning, 29.5% were impaired on Immediate recall, 36.1% on Short Delay, and 44.0% on Long Delay Recall. Impairment rates for Craft Story Immediate and Delayed Recall (Paraphrase) were 15.7% and 18.7%, respectively. 19.9% and 15.7% were impaired on learning and delayed recall of the Brief Visuospatial Memory Test‐Revised. Impairments were frequent on the Multilingual Naming Test (20.5%), Trail Making Test Parts B (19.3%) and A (18.1%), Animal Fluency (15.7%), and Number Span Backward (15.1%). Impairments were less common (&lt;10%) for phonemic fluency, planning, basic attention, and visual‐perceptual abilities, Mean FAQ was 3.11 (SD=5.14); 23 (13.9%) had an FAQ &gt;9. Based on QDRS scores, 66 (39.8%) had mild cognitive impairment, 44 (26.5%) mild dementia, and 6 (3.6%) moderate dementia.ConclusionsIn these former American football players, neuropsychological impairments were most frequent in episodic memory, followed by confrontation naming and executive function. Further research is needed to delineate this population’s unique neuropsychological profile.

Sleep disruption and disorders in former college and professional American football players

AbstractBackgroundLittle is known about sleep in those with a history of contact sports, who are at increased risk for neurodegenerative disease(s). Sleep disruption and disorders are increasingly recognized as having a bidirectional relationship with Alzheimer’s disease neuropathology. Here, we investigated self‐reported sleep disruption and disorders in male former college and professional American football players.Method116 former National Football League (NFL) players, 60 former college football players, and 60 asymptomatic men without a history of traumatic brain injury or repetitive head impacts (controls), all between 45‐74 years, completed the Mayo Sleep Questionnaire (MSQ) which includes the Epworth Sleepiness Scale (ESS). Former American football players were enrolled across the spectrum of symptom severity (asymptomatic to mild dementia). Using binary logistic regression or analysis of covariance, comparisons (controlling for age, racial identity, body mass index, APOE e4 status) on each of the MSQ items and the ESS were made between each of the study groups.ResultCompared to controls, former NFL players were more likely to restless legs (OR = 7.32, 95% CI = 1.63‐32.97*), sleepwalking (OR = 8.65, 95% CI = 1.08‐69.22*), observed apnea (OR = 2.25, 95% CI = 1.04‐4.85*), lower alertness levels (marginal mean diff. = 0.90**) and had higher ESS (marginal mean diff. = 2.37**). Former college football players reported greater sleep disturbances compared with controls: restless legs (OR = 10.82, 95% CI = 1.86‐62.89**), sleepwalking (OR = 10.45, 95% CI = 1.12‐97.58*), alertness levels (marginal mean diff. = 1.48**) and ESS (marginal mean diff. = 2.76*). There were no college vs control differences for observed apnea. There were no differences between former NFL players and former college football players on any sleep metric. **p&lt;.005, *p&lt;.05.ConclusionSleep disturbances may be an important factor to investigate in those with a history of participation in American football.

Long‐term effects of repetitive head impacts on gray matter cortical thickness

AbstractBackgroundRepetitive head impact (RHI) exposure has been associated with the neurodegenerative disease chronic traumatic encephalopathy (CTE). Magnetic resonance imaging (MRI) and postmortem research suggest frontotemporal atrophy may be characteristic of CTE. The late effects of RHI on cortical volume remain poorly understood due to focus on male former professional American football players and lack of examination of specific lobar gyri. We leveraged the Boston University Alzheimer’s Disease Research Center (BU ADRC) to compare frontal, temporal, and parietal gyri gray matter thickness between participants with and without RHI exposure.Method39 participants exposed to RHI and 33 similar‐aged (+/‐ 5 years) participants without RHI from the BU ADRC, all spanning the cognitive continuum, underwent MRI on a 3T Philips. Freesurfer was used to derive regional gray matter cortical thickness values. For the frontal, temporal, and parietal lobes, we computed mean composites of superior, middle, and inferior gyri gray matter measures. Analysis of covariance compared participants with and without RHI, controlling for age, sex, race, education and hippocampal volume.ResultMean age was 62.31 (SD=8.87), 34 (47.2%) were female, and 65 (90.3%) were White. Of the RHI group, 23 (59.0%) played American football, 9 (23.1%) ice hockey, 5 (12.8%) were boxers, and 3 (7.7%) were amateur wrestlers. Compared to non‐RHI, RHI‐exposed participants had decreased gray matter thickness of superior (marginal mean diff [MD]=0.10, p&lt;0.01) and middle frontal gyri (MD=0.06, p=0.03), and the middle temporal gyrus (MD=0.07, p=0.03). There were no differences in gray matter thickness for inferior frontal, superior or inferior temporal, or parietal gyri. Because the CTE tau lesion is uniquely at the sulcal depths, we examined the gray matter thickness of the banks of superior temporal sulcus and RHI participants had reduced thickness (MD=0.09, p=0.02).ConclusionFrontotemporal atrophy may be a characteristic late effect of RHI exposure. Further examination of thickness of different lobar gyri in the setting of RHI may facilitate disease differentiation. Larger samples will be important to examine how the effects of RHI on gray matter cortical thickness differ by sex, sport played, etc.

Treatment Outcomes in American Football Players After Intervertebral Disk Herniation: Systematic Review and Meta-Analysis.

American football players are at increased risk for many forms of spinal injury. Intervertebral disk herniations are particularly concerning as they are the leading cause of days lost to injury and can have long-term effects on player careers. Disk herniation management plays a major role in the likelihood and success of return-to-play (RTP). To assess the incidence, demographic variables, treatment approaches, outcomes, and RTP rates of disk herniations in American football players. A systematic review of the literature investigating disk herniations in American football players using PubMed, Cochrane Library, and Embase was performed. RTP estimates were calculated by pooling study-specific data using a random-effects model. Four hundred twenty-two studies were identified, with 18 meeting inclusion criteria. Offensive and defensive linemen were the 2 most commonly injured positions. Players undergoing operations were on average younger, with higher body mass indexes, fewer seasons played, and longer post-treatment careers than nonsurgical counterparts. Postsurgical recovery periods lasted an average 106 d, with a mean RTP duration of 33 games over 2.7 yr and an 8.45% reoperation rate. Operative treatment offered a nonsignificant increase in the likelihood of return-to-play compared with nonoperative treatment (odds ratio = 2.81, 95% CI 0.83-9.51). Disk herniations are a common injury, with surgery potentially improving post-treatment outcomes. The literature suffers from heterogeneous definitions of RTP and varying performance metrics, making it difficult to draw clear conclusions. To better understand the impact of disk herniation and treatment on player health and performance, more studies should be performed prospectively and with standardized metrics.

Commentary: Treatment Outcomes in American Football Players After Intervertebral Disk Herniation: Systematic Review and Meta-Analysis.

*Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA; ‡Vanderbilt Sports Concussion Center, Nashville, Tennessee, USA Correspondence: Scott L. Zuckerman, MD, MPH, Department of Neurological Surgery, Vanderbilt University Medical Center, 1500 21st Ave, 4340 Village at Vanderbilt, Nashville, TN 37212, USA. Email: [email protected]

High cognitive demand tasks may detect mild alterations in executive functions in American football players: A pilot study

High cognitive demand tasks may detect mild alterations in executive functions in American football players: A pilot study

Effect of “FIFA 11+” warm up program on fatigue, sleep quality, muscle flexibility and psychological status among amateur football players

Purpose: Although “FIFA 11+” warm up program was developed with the primary purpose of decreasing the risk of injuries, it is also a good warm-up program. Therefore this study was designed to explore possible effects of “FIFA 11+” warm up program on fatigue, sleep quality, muscle flexibility and psychological status among amateur football players in Lagos state.

Influence of play type on the magnitude and number of head impacts sustained in youth American football

The magnitude and number of head impacts experienced by young American football players are associated with negative brain health outcomes and may be affected by play-type strategies. The purpose of this research was to examine how play type affects the magnitude and number of head impacts in youth American tackle football. Head impacts were recorded for 30 games in the 5–9 age category and 30 games in the 9–14 age category. Impacts using physical and finite element models were conducted to determine the brain strain. Run plays had a higher head impact frequency in both age groups (p < 0.05). This increase in head impacts was consistent for all positions (p < 0.05), except wide receiver, and offensive line and defensive back in the 9–14 age group (p > 0.05). Both age groups experienced significantly different magnitude proportions with higher numbers of very low and low strain magnitude impacts during run plays (p < 0.05), and a higher proportion of moderate magnitude impacts in the 5–9 age category (p < 0.05). This data can be used to inform and educate teams and coaches and influence decisions around the use of runs and passing plays that may lead to a decrease in head impacts.

Futsal As a Means of Improving Women Football Players' Playing Skills : A Qualitative Assessment of Player Perceptions

The purpose of this study was to determine whether futsal could help improve playing skills for women football player. Some researchers claim that futsal can help in enhancing football playing skills. However, no studies have been conducted on women football player; the research was conducted on men's football players. Futsal was created as an indoor variant of football. With that in mind, it is fair to suggest futsal as many of the techniques and skills required are similar to football, such as controlling the ball, shooting, passing and shooting. This research is qualitative, data collection using open questions conducted through the google form application.The participants in this study were amateur women football player who had participated in futsal. This article wants to show that futsal can positively impact improving skills for women football player.

The Effectiveness of Constraints-Led Training on Skill Development in Football

This study aimed to examine whether constraints-led training improved technical skills in young football players. Twenty-four Under-13 amateur football players were divided into two groups: the experimental group (CLA; n = 12) participated in the Constraints-led training protocol; the control group (n = 12) performed conventional training sessions based on the cognitive approach. The study consisted of a pre-test, two months of training intervention, and a post-test. Contextualized technical skills were tested using the Speed dribbling Test. The experimental CLA group recorded notable improvements in the observation variable, respectively: (d [95% CI] = 0.90 [0.70; 0.94] P <0.05). The control group, on the other hand, did not show significant changes (P> 0.05). From the ANOVA repeated measurements, it was possible to appreciate a significant group x moment interaction, respectively: (d [95% CI] = 0.77 [0.54; 0.85] P <0.05). Participants who practiced with the constraint-driven training protocol demonstrated significant improvements in dribbling accuracy while reducing execution errors. This suggests that integrating CLA as a tool in a football training program can have a positive impact on their technical skills.

Factors Associated With the Mechanism of ACL Tears in the National Football League: A Video-Based Analysis.

Background:The factors associated with anterior cruciate ligament (ACL) injury mechanism in professional American football players are not well-understood.Hypothesis:It was hypothesized that football-related and player-specific factors, such as position and body mass index (BMI), are associated with ACL injury mechanism in these athletes.Study Design:Descriptive epidemiology study.Methods:Videos of ACL tears occurring in National Football League (NFL) games over 6 consecutive seasons from 2014 to 2019 were reviewed by 2 orthopaedic surgeons who specialize in sports medicine. For each injury, the role of contact (direct contact [contact to the injured knee/lower extremity], indirect contact [contact not involving the injured knee/lower extremity], or no contact) as well as playing situation and lower extremity position were recorded. Additional player characteristics, timing of injury, and surface information were obtained from NFL game-day and injury database statistics.Results:Of the 140 ACL tears, a minority occurred via direct contact to the injured lower extremity (30%), although this varied by position. Just over two-thirds (70%) of ACL tears in offensive linemen occurred via direct contact to the injured lower extremity, while wide receivers had no direct contact ACL tears. Elevated BMI was associated with a greater likelihood of ACL tears occurring via direct contact (53% in players with BMI ≥35 kg/m2 vs 24% in players with BMI <35 kg/m2; P = <.01). Rookies had the lowest percentage of direct contact ACL tears (18%; P = .22). ACL tears that occurred during the middle 8 weeks of the regular season resulted more often from direct contact (38%; P = .06). ACL tears that occurred in the third quarter were the most likely to occur via direct contact (44%), while those that occurred in the fourth quarter were the least likely to occur via direct contact (13%; P < .01).Conclusion:Although most NFL players sustained ACL tears via a noncontact mechanism (ie, through indirect or no contact), players with an elevated BMI, especially on the offensive line, were more likely to injure their ACL through direct contact. Position-dependent variance in injury mechanism may help guide injury prevention efforts in these athletes.

Using Random Forest Regression to Determine Influential Force-Time Metrics for Countermovement Jump Height: A Technical Report.

Merrigan, JJ, Stone, JD, Wagle, JP, Hornsby, WG, Ramadan, J, Joseph, M, and Hagen, JA. Using random forest regression to determine influential force-time metrics for countermovement jump height: a technical report. J Strength Cond Res 36(1): 277-283, 2022-The purpose of this study was to indicate the most influential force-time metrics on countermovement jump (CMJ) height using multiple statistical procedures. Eighty-two National Collegiate Athletic Association Division I American football players performed 2 maximal-effort, no arm-swing, CMJs on force plates. The average absolute and relative (i.e., power/body mass) metrics were included as predictor variables, whereas jump height was the dependent variable within regression models (p < 0.05). Best subsets regression (8 metrics, R2 = 0.95) included less metrics compared with stepwise regression (18 metrics, R2 = 0.96), while explaining similar overall variance in jump height (p = 0.083). Random forest regression (RFR) models included 8 metrics, explained ∼93% of jump height variance, and were not significantly different than best subsets regression models (p > 0.05). Players achieved higher CMJs by attaining a deeper, faster, and more forceful countermovement with lower eccentric-to-concentric force ratios. An additional RFR was conducted on metrics scaled to body mass and revealed relative mean and peak concentric power to be the most influential. For exploratory purposes, additional RFR were run for each positional group and suggested that the most influential variables may differ across positions. Thus, developing power output capabilities and providing coaching to improve technique during the countermovement may maximize jump height capabilities. Scientists and practitioners may use best subsets or RFR analyses to help identify which force-time metrics are of interest to reduce the selectable number of multicollinear force-time metrics to monitor. These results may inform their training programs to maximize individual performance capabilities.