American Football Players Research Articles

Megaformer as a Rehabilitation Modality for Hamstring Strain Injury in Division I American Football: A Case Study

BACKGROUND: With athletes striving for peak performance, noncontact muscle strain injuries are increasingly common. Hamstring strain injuries (HSIs) make up the largest portion of noncontact injuries and provide further difficulty because of the high reinjury rate. This case study explores the Megaformer as a modality to treat HSIs with the potential to reduce the return to play timetable and recurrence rate. CASE PRESENTATION: A 23-year-old male American football player with a history of hamstring injuries presented with pain in the right proximal hamstring and deficits in strength and mobility testing as a result of sustained hyperflexion of the right hip with full knee extension. Magnetic resonance imaging (MRI) confirmed a recurrent proximal hamstring strain. OUTCOME AND FOLLOW-UP: Subsequent strength and range of motion testing revealed no impactful tenderness or pain during active participation or palpation after 9 days, and complete alleviation of symptoms at 6 weeks. No reinjury occurred during the remaining football season. DISCUSSION: This case study highlights possible advantageous features of the Megaformer as a recovery modality for HSIs. The Megaformer aims to improve flexibility, strengthen primary and secondary muscles, and enhance neuromuscular coordination to attempt to decrease the return to play timetable and reduce injury recurrence.

The Reliability and Validity of the Rebound Countermovement Jump in National Collegiate Athletic Association Division I American Football Players.

Talpey, SW, Drake, M, Haintz, L, Belanger, A, O'Grady, MW, Young, WB, Mundy, PD, James L, Gabbett, TJ, Gardner, EC. The reliability and validity of the rebound countermovement jump in National Collegiate Athletic Association Division I American Football Players. J Strength Cond Res XX(X): 000-000, 2024-The purpose of this study was to investigate the reliability and validity of the rebound countermovement jump (R-CMJ), as an alternate test of leg muscle function to the CMJ and drop jumps (DJs). Because the first phase of the R-CMJ mimics that of the CMJ, it is hypothesized that variables obtained in phase I of the R-CMJ will be like those of a CMJ. Similarly, because the second phase of a R-CMJ mimics a DJ, it is believed that the variables obtained from phase II will be like those from a DJ. Collegiate male American football players (N = 46) aged 18-24 years completed CMJs and R-CMJs on a portable force plate. Tests were completed on 3 separate days to determine the repeatability of select variables and to establish their validity. In addition, a subgroup (N = 20) of players from the cohort completed DJs from both 30 cm (DJ30) and 45 cm (DJ45) to determine the concurrent validity of the variables obtained from the second phase of the R-CMJ. Most variables obtained from the CMJ and R-CMJ phase I were found to be reliable, except for time-to-take-off. The variables from the DJ30, DJ45, and R-CMJ phase II displayed moderate to good reliability; however, all coefficient of variations were >10%. Jump height achieved in the CMJ was significantly greater than that achieved in phase I of the R-CMJ. The reactive strength index was significantly different in the R-CMJ compared with the DJ from both 30 and 45 cm heights. Although the R-CMJ may be inviting for coaches to use owing to its ease and time efficiency, the results of this study highlight that it may not provide a valid representation of an athlete's reactive strength.

Injury Characteristics and Risk Factors of Sport-Related Concussion Among High School Athletes in School-Sponsored Sports.

Over a million sport-related concussions (SRC) affect children annually in the United States, posing a significant public health concern. Limited data exist on the premorbid risk factors and injury characteristics of SRCs in high school athletes. This study aims to understand acute SRC injury characteristics and describe premorbid risk factors in high school athletes. Athletes (aged 14-19 years) from 19 central Illinois high schools participating in school-sponsored sports from 2009 to 2023 were included. Sports Concussion Assessment Tool evaluations were performed as part of preseason and postinjury evaluations. Injury characteristics, such as mechanism, setting, and symptoms, were described using all SRCs in the study period. Odds ratios (OR) were computed to determine risk factors using athletes with a baseline Sports Concussion Assessment Tool before SRC and nonconcussed athletes. In total, 4360 athletes were included (3953 without SRC; 407 with ≥1 SRC of whom 168 had a previous baseline). Overall, 24.2% of SRCs occurred in female athletes, and most SRCs occurred in competitions while playing American football (52.3%), soccer (20.4%), and basketball (7.6%). Blow/hit to the head was the most common mechanism. Headache was the most severe symptom (2.55 ± 1.51 [SD]), and symptoms of emotionality and nervousness/anxiety were significantly more severe in female athletes (P < .05). Students with previous concussions (OR 2.64 95% CI [1.81, 3.78]), previous hospitalization for head injury (OR 3.19 95% CI [1.9, 5.14]), headache/migraine disorders (OR 2.23 95% CI [1.29, 3.66]), and learning disabilities (OR 2.69 95% CI [1.47, 4.61]) had greater odds of SRC (P < .05). Lower odds of SRC were seen in athletes identifying as Black or African American (vs White) (OR 0.54 95% CI [0.32, 0.86]) and those attending larger (vs smaller) schools (OR 0.64 95% CI [0.46, 0.88]). Understanding SRC risk factors and characteristics in high school athletes is critical for developing prevention and management programs, guiding neurosurgeons in mitigating SRC risk, and informing return-to-play decisions.

Chronic traumatic encephalopathy in athletes, players, boxers and military: systematic review

The objective of the study was to demonstrate whether athletes, players, boxers and military personnel can really be victims of CTE, and to elucidate this pathology. In 53 articles, 14 were selected for qualitative synthesis in the results table that addresses CTE in football, soccer and rugby players, boxers and the military. Neuropathologically, CTE shows cerebral atrophy, a pelvic septum cavity with fenestrations, dense diffuse immunoreactive inclusions and a TDP-43 proteinopathy. Microscopically, there are extensive neurofibrillary tangles and spindle-shaped neurites throughout the brain. Thus, CTE is characterized by being a distinct tauopathy and with a clear environmental etiology. American football players, boxers and the military are more likely to trigger CET, due to the constant mechanical shocks from their heads. The most frequent clinical manifestations were: headache, aggressiveness, dementia, executive dysfunction and suicide. CET is definitely diagnosed only at autopsy, there is no specific treatment for it, but support and safety measures can help the patient. Advances to definitively diagnose CTE in living people and specific treatment for this disease are needed.

On-field concurrent validity of flight time-based countermovement jump height during fatigue: A comparison between inertial measurement units worn at different locations on the body

ABSTRACT We explored the feasibility of utilizing immediate changes in flight time-based vertical countermovement jump height as an on-field measure for fatigue-induced decrements in performance. Comparing Inertial Measurement Units (IMUs) worn at five body locations (feet, shorts for thighs and pelvis, waist strap, and thorax in a standard GPS vest) with a force plate as a reference, we enlisted 19 amateur football players who performed a series of 10 maximal 30 m sprints (initiated every minute). Maximal jumps were executed immediately before and after each sprint, with the latter jumps recorded on a force plate integrated into the field. Bland Altman’s bias (−0.49 cm) and limits of agreement (1.01 cm) were minimal for the feet IMUs. The thorax IMU had the highest bias (−6.35 cm), but the limits of agreement (2.73 cm) were similar to the other locations. Repeated measures correlations (rmcorr) between force plate and IMUs were excellent for the feet (rmcorr = 0.98) and good for the thorax (rmcorr = 0.86) and other locations except for the waist strap. In the fatigued state, within-session coefficients of variation ranged from 4.0% (pelvis in shorts) to 6.5% (waist strap). These findings suggest that body-worn IMUs possess the potential for a prompt and straightforward on-field vertical jump assessment to monitor acute fatigue.

Assessment of Blood Pressure Levels and Left Ventricular Functions of American Football Players in Türkiye

Assessment of Blood Pressure Levels and Left Ventricular Functions of American Football Players in Türkiye

Assessment of Eating Disorder Risk According to Sport Level, Sex, and Social Media Use among Polish Football Players: A Cross-Sectional Study

Background/Objectives: Eating disorders (EDs) pose a significant health issue affecting athletes, with risk factors varying by sport level, sex, and social media use. This study assesses the risk of EDs among professional and amateur football players, considering these factors, and compares findings with a control group of non-athletes. Methods: The study involved 170 participants, including non-athletes as a control group, categorized by sex and sport level. The mean age of participants was 24.3 ± 4.20, with an age range of 18–36. The Eating Attitudes Test (EAT-26) and body mass index (BMI) assessments were used to determine ED risk. Results: Results showed a higher prevalence of ED risk among professional athletes, especially women, compared to amateurs and non-athletes. Social media use and body comparisons were linked to increased ED risk, with professional athletes exhibiting higher vulnerability due to performance pressures. Women, particularly those in professional sports, showed a higher risk of EDs than men, influenced by social and aesthetic pressures. Conclusions: The findings highlight the need for targeted interventions, promoting healthier body image perceptions and addressing social media’s role in shaping body dissatisfaction. Psychological support and sex-specific strategies should be integrated into athlete care programs to mitigate these risks.

An Effective Method of Aerobic Capacity Development: Combined Training with Maximal Aerobic Speed and Small-Sided Games for Amateur Football Players

This study aimed to investigate the effects of combined training with maximal aerobic speed and small-sided games on football players’ aerobic capacity development. Methods: The football players were divided into three groups as a combined training group (n = 20) (Mean ± SD age 23.40 ± 2.92 yrs, BMI was 23.67 ± 1.59 kg/m2, mass: 74.80 ± 5.46 kg, height: 177.73 ± 4.31 cm), maximal aerobic speed group (n = 20) (Mean ± SD age 23.93 ± 2.46 yrs, BMI was 23.32 ± 1.42 kg/m2, mass: 72.66 ± 5.38 kg, height: 176.46 ± 4.99 cm) and regular training group (n = 20) (Mean ± SD age 24.80 ± 5.84 yrs, BMI was 22.87 ± 1.67 kg/m2, mass: 73.06 ± 6.74 kg, height: 178.33 ± 7.98 cm). In addition to regular football training, maximal aerobic speed training with small-sided games was applied to the combined training group (CT) and only maximal aerobic speed training was applied to the maximal aerobic speed group (MAS) twice a week for 12 weeks. The normal training group (NT) continued their routine football training programme. All participants applied the Yo-Yo IR1 test in the pre-test and post-test of the study. As a result of normality tests, it was determined that the data showed normal distribution, and the ANOVA test and Tukey’s multiple comparison test were used in the intergroup evaluation. Results: When the Yo-Yo IR1 Test pre-test and post-test results were analysed, maximal aerobic speed training with small-sided games (CT) and maximal aerobic speed (MAS) groups were significantly higher compared to the normal training (NT) group regarding training load, running distance, and VO2max value among the football players (p = 0.001). There was no difference in the normal training group (p &gt; 0.05). As a result, it was determined that combined training with maximal aerobic speed, small-sided games, and only maximal aerobic speed effectively improved football players’ aerobic capacity and general performance.

Cavum Septum Pellucidum in Former American Football Players: Findings From the DIAGNOSE CTE Research Project.

Exposure to repetitive head impacts (RHI) is linked to the development of chronic traumatic encephalopathy (CTE), which can only be diagnosed at post-mortem. The presence of a cavum septum pellucidum (CSP) is a common finding in post-mortem studies of confirmed CTE and in neuroimaging studies of individuals exposed to RHI. This study examines CSP in living former American football players, investigating its association with RHI exposure, traumatic encephalopathy syndrome (TES) diagnosis, and provisional levels of certainty for CTE pathology. Data from the DIAGNOSE CTE Research Project were used to compare the presence and ratio of CSP in former American football players (n = 175), consisting of former college (n = 58) and former professional players (n = 117), and asymptomatic unexposed controls without RHI exposure (n = 55). We further evaluated potential associations between CSP measures and cumulative head impact index (CHII) measures (frequency, linear acceleration, and rotational force), a TES diagnosis (yes/no), and a provisional level of certainty for CTE pathology (suggestive, possible, and probable). Former American football players exhibited a higher CSP presence and ratio than unexposed asymptomatic controls. Among player subgroups, professional players showed a greater CSP ratio than former college players and unexposed asymptomatic controls. Among all football players, CHII rotational forces correlated with an increased CSP ratio. No significant associations were found between CSP measures and diagnosis of TES or provisional levels of certainty for CTE pathology. This study confirms previous findings, highlighting a greater prevalence of CSP and a greater CSP ratio in former American football players compared with unexposed asymptomatic controls. In addition, former professional players showed a greater CSP ratio than college players. Moreover, the relationship between estimates of CHII rotational forces and CSP measures suggests that cumulative frequency and strength of rotational forces experienced in football are associated with CSP. However, CSP does not directly correlate with TES diagnosis or provisional levels of certainty for CTE, indicating that it may be a consequence of RHI associated with rotational forces. Further research, especially longitudinal studies, is needed for confirmation and to explore changes over time.

Knee

The October 2024 Knee Roundup360 looks at: Managing the unexpected: treatment of intraoperative medial collateral ligament injuries; Identifying subgroups of patients that may benefit from robotic arm-assisted total knee arthroplasty: secondary analysis of data from a randomized controlled trial; Cost-effectiveness of enoxaparin versus aspirin in the prevention of venous thromboembolism after total hip or knee arthroplasty: an analysis from the CRISTAL cluster-randomized trial; Cartilage regeneration and long-term survival in medial knee osteoarthritis patients treated with high tibial osteotomy and osteochondral autologous transfer system; Treatment of chronic and complex meniscal tears with arthroscopic meniscus repair augmented with collagen matrix wrapping: failure rate and functional outcomes; Long-term outcomes of multiligament knee injuries in American football players.

Examination of plasma biomarkers of amyloid, tau, neurodegeneration, and neuroinflammation in former elite American football players.

Blood-based biomarkers offer a promising approach for the detection of neuropathologies from repetitive head impacts (RHI). We evaluated plasma biomarkers of amyloid, tau, neurodegeneration, and inflammation in former football players. The sample included 180 former football players and 60 asymptomatic, unexposed male participants (aged 45-74). Plasma assays were conducted for beta-amyloid (Aβ) 40, Aβ42, hyper-phosphorylated tau (p-tau) 181+231, total tau (t-tau), neurofilament light (NfL), glial fibrillary acidic protein (GFAP), interleukin-6 (IL-6), Aβ42/p-tau181 and Aβ42/Aβ40 ratios. We evaluated their ability to differentiate the groups and associations with RHI proxies and traumatic encephalopathy syndrome (TES). P-tau181 and p-tau231(padj=0.016) were higher and Aβ42/p-tau181 was lower(padj=0.004) in football players compared to controls. Discrimination accuracy for p-tau was modest (area under the curve [AUC]=0.742). Effects were not attributable to AD-related pathology. Younger age of first exposure (AFE) correlated with higher NfL (padj=0.03) and GFAP (padj=0.033). Plasma GFAP was higher in TES-chronic traumatic encephalopathy (TES-CTE) Possible/Probable (padj=0.008). Plasma p-tau181 and p-tau231, GFAP, and NfL may offer some usefulness for the characterization of RHI-related neuropathologies. Former football players had higher plasma p-tau181 and p-tau231 and lower Aβ42/ptau-181 compared to asymptomatic, unexposed men. Younger age of first exposure was associated with increased plasma NfL and GFAP in older but not younger participants. Plasma GFAP was higher in participants with TES-CTE possible/probable compared to TES-CTE no/suggestive.

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.

Health outcomes of former division I college athletes

ABSTRACT Background Former professional collision sport (CS) athletes, particularly American football players, are at risk of developing chronic health conditions; however, little is known about the health outcomes of amateur athletes. Methods A 60-item health survey examined self-reported symptoms and diagnoses among former Division 1 Collegiate CS athletes and non- or limited-contact sport (non-CS) athletes. Binary logistic regressions tested the association between playing CS and health outcomes. Results Five hundred and two (6.2%) participants completed the survey: 160 CS athletes (mean age: 59.2, SD = 16.0) and 303 non-CS athletes (mean age: 54.0, SD = 16.9). CS athletes had increased odds of reported cognitive complaints and neuropsychiatric symptoms including memory (Padj < 0.01), attention/concentration (Padj = 0.01), problem solving/multi-tasking (Padj = 0.05), language (Padj = 0.02), anxiety (Padj = 0.04), impulsivity (Padj = 0.02), short-fuse/rage/explosivity (Padj < 0.001), and violence/aggression (Padj = 0.02). CS athletes also reported higher rates of sleep apnea (Padj = 0.02). There were no group differences in cardiovascular and physical health outcomes. Conclusions Former CS athletes reported more cognitive and neuropsychiatric complaints. The low response rate is a limitation of this study; however, over 500,000 athletes play college sports each year, thus research on long-term health outcomes in this population is critical.

B - 55 Diffusion Tensor Imaging Analysis of Former American Football Players Exposed to Repetitive Head Impacts

Abstract Objective Exposure to repetitive head impacts (RHI) has been linked to Chronic Traumatic Encephalopathy (CTE) and neuropathological alterations such as white matter shear injuries. In this study, we use diffusion-tensor imaging (DTI) to investigate in vivo white matter alterations among former American football players. We also investigate how age and factors associated with RHI exposure influence white matter integrity. Methods We analyzed data from the DIAGNOSE CTE Research Project, focusing on former American football players (n = 166). The measures included whole-brain Fractional Anisotropy (FA), reflecting water diffusion directionality in white matter, and FreeWater-corrected FA (FAt) accounting for extracellular free water, using FSL Tract-Based Spatial Statistics (TBSS). We performed linear regressions on FA and FAt with age, age of first exposure to football, and estimates of cumulative head impact index (CHII) scores of frequency, linear acceleration, and rotational force controlling for age, body mass index, race, education, and APOE e4 allele presence as covariates. Results Both FA (p &amp;lt; 0.00001) and FAt (p &amp;lt; 0.00001) decreased as age increased. Moreover, FA (p &amp;lt; 0.01) and FAt (p &amp;lt; 0.01) were significantly lower with an earlier age of first exposure to football. Finally, FAt decreased as CHII linear acceleration (p &amp;lt; 0.04) and rotational forces (p &amp;lt; 0.02) increased. Conclusion Our study reveals age-related declines in both FA and FAt and highlights that the duration and intensity of exposure to RHI have an impact on white matter microstructure later in life. Overall, these results underscore the impact of prolonged exposure to RHI on white matter microstructure.

Clinical and Neuropathological Correlates of Substance Use in American Football Players.

Chronic traumatic encephalopathy (CTE) is a neurodegenerative tauopathy more frequently found in deceased former football players. CTE has heterogeneous clinical presentations with multifactorial causes. Previous literature has shown substance use (alcohol/drug) can contribute to Alzheimer's disease and related tauopathies pathologically and clinically. To examine the association between substance use and clinical and neuropathological endpoints of CTE. Our sample included 429 deceased male football players. CTE was neuropathologically diagnosed. Informant interviews assessed features of substance use and history of treatment for substance use to define indicators: history of substance use treatment (yes vs no, primary variable), alcohol severity, and drug severity. Outcomes included scales that were completed by informants to assess cognition (Cognitive Difficulties Scale, BRIEF-A Metacognition Index), mood (Geriatric Depression Scale-15), behavioral regulation (BRIEF-A Behavioral Regulation Index, Barratt Impulsiveness Scale-11), functional ability (Functional Activities Questionnaire), as well as CTE status and cumulative p-tau burden. Regression models tested associations between substance use indicators and outcomes. Of the 429 football players (mean age = 62.07), 313 (73%) had autopsy confirmed CTE and 100 (23%) had substance use treatment history. Substance use treatment and alcohol/drug severity were associated with measures of behavioral regulation (FDR-p-values<0.05, ΔR2 = 0.04-0.18) and depression (FDR-p-values<0.05, ΔR2 = 0.02-0.05). Substance use indicators had minimal associations with cognitive scales, whereas p-tau burden was associated with all cognitive scales (p-values <0.05). Substance use treatment had no associations with neuropathological endpoints (FDR-p-values>0.05). Among deceased football players, substance use was common and associated with clinical symptoms.

Assessment of Nutritional Knowledge, Alcohol and Tobacco Consumption in Amateur and Elite Youth Football Players

Introduction: Nutrition is increasingly recognized as a key component of optimal sports performance. On the other hand, insufficient and continuous food intake can compromise athletic performance and success where Nutritional Knowledge can play a leading role. Methods: One hundred and three youth athletes from 6 different clubs belonging to the District, Honor, and National Championship participated in this study. To assess Nutritional Knowledge, consumption of alcohol and tobacco the Abridged Nutrition for Sport Knowledge Questionnaire was applied. Results: The percentage of Nutritional Knowledge obtained in the District Championship was 31.25%, in the Honors it was 35.56% and in the National Championship it was 35.02%. No significant differences were found between the Nutritional Knowledge of athletes. In turn, there were statistical differences in the consumption of alcohol and tobacco among the athletes of the 3 Championships, with the District division having the highest percentage of smokers (100%) and alcohol consumers (42.6%). Conclusion: It is essential to increase the Nutritional Knowledge observed in these young athletes since it can have an influential role in their food choices.

Nutritional Optimization for Brain Health in Contact Sports: A Systematic Review and Meta-Analysis on Long-Chain ω-3 Fatty Acids and Neurofilament Light

Accumulating evidence has highlighted the acute and chronic impact of repetitive subconcussive head impacts (rSHIs) in contact sports. Neurofilament-light (Nf-L), a brain-derived biomarker of neuroaxonal injury, elevates in concert with rSHI. Recently, long-chain ω-3 polyunsaturated fatty acids (LC ω-3 PUFAs) supplementation has been suggested to mitigate brain injury from rSHI as reflected by attenuation of Nf-L concentrations within contact sport athletes. Using a systematic review with a meta-analysis, we aimed to determine the effect of LC ω-3 PUFA supplementation on Nf-L concentrations in athletes routinely exposed to rSHI. Electronic databases (PubMed and CINAHL) were searched from inception through January 2024. One-stage meta-analysis of individual participant-level data was used to detect changes in Nf-L concentrations between LC ω-3 PUFA and control/placebo (PL) groups from baseline to midseason (MS) and postseason (PS). Least square means (±SE) for Nf-L change from baseline were compared by treatment group for MS/PS using contrast t tests. Significance was set a priori at adjusted P ≤ 0.05. Of 460 records identified, 3 studies in collegiate American football players (n = 179; LC ω-3 PUFA = 105, PL = 71) were included in the meta-analysis. Compared with PL, the change in Nf-L concentrations was statistically similar at MS [mean difference (MD) = –1.66 ± 0.82 pg·mL–1, adjusted P = 0.09] and significantly lower at PS (MD = –2.23 ± 0.83 pg·mL–1, adjusted P = 0.02) in athletes following LC ω-3 PUFA supplementation. Our findings demonstrate preliminary support for the prophylactic administration of LC ω-3 PUFA in contact sport athletes exposed to rSHI; however, further research is required to determine the effective dosage required.This trial was registered at OSF (DOI: https://doi.org/10.17605/OSF.IO/EY5QW).

Lower limb injuries in american football players in Poland.

The aim of the study was to determine the location and types of injuries in the lower limbs in American football players in Poland. The circumstances of the injuries were identified, with particular emphasis on the player's position on the field. Original questionnaire to investigate 70 consecutive Polish players was used. Analyses as a whole and divided into offensive and defensive players were carried out. Overall, injuries to both lower limbs accounted for 17.1%, injuries to the right lower limb to 37.2%, and injuries to the left limb to 29%. Ankle injuries were the most common, both offensive and defensive, accounting for 58.5% and 48.3% of lower limb injuries, respectively. Injuries to muscles, tendons and ligaments were more common in defensive players (55.2%), while in offensive sprains (52.5%), fractures (19.5%), and contusions (17.1%). The incidence of lower limb injuries was higher in general during training than competitions and in the case of offensive players (14.6%). Coaching American football increases the risk of foot injury, accounting for 10% of lower limb injuries. The obtained results indicate the need to strengthen the ligamentous-muscular complex of the lower limbs. Lower limb injuries are more common among offensive players than defensive. Offensive players are twice as likely to suffer from foot injuries. Lower limb injuries are more common during training, compared to competitions, both offensively and defensively.

Repetitive Head Impacts and Perivascular Space Volume in Former American Football Players

Exposure to repetitive head impacts (RHI) is associated with increased risk for neurodegeneration. Accumulation of toxic proteins due to impaired brain clearance is suspected to play a role. To investigate whether perivascular space (PVS) volume is associated with lifetime exposure to RHI in individuals at risk for RHI-associated neurodegeneration. This cross-sectional study was part of the Diagnostics, Imaging, and Genetics Network for the Objective Study and Evaluation of Chronic Traumatic Encephalopathy (DIAGNOSE CTE) Research Project, a 7-year multicenter study consisting of 4 US study sites. Data were collected from September 2016 to February 2020 and analyses were performed between May 2021 and October 2023. After controlling for magnetic resonance image (MRI) and processing quality, former American football players and unexposed asymptomatic control participants were included in analyses. Prior exposure to RHI while participating in American football was estimated using the 3 cumulative head impact indices (CHII-G, linear acceleration; CHII-R, rotational acceleration; and CHII, number of head impacts). Individual PVS volume was calculated in the white matter of structural MRI. Cognitive impairment was based on neuropsychological assessment. Linear regression models were used to assess associations of PVS volume with neuropsychological assessments in former American football players. All analyses were adjusted for confounders associated with PVS volume. Analyses included 224 participants (median [IQR] age, 57 [51-65] years), with 170 male former football players (114 former professional athletes, 56 former collegiate athletes) and 54 male unexposed control participants. Former football players had larger PVS volume compared with the unexposed group (mean difference, 0.28 [95% CI, 0.00-0.56]; P = .05). Within the football group, PVS volume was associated with higher CHII-R (β = 2.71 × 10-8 [95% CI, 0.50 × 10-8 to 4.93 × 10-8]; P = .03) and CHII-G (β = 2.24 × 10-6 [95% CI, 0.35 × 10-6 to 4.13 × 10-6]; P = .03). Larger PVS volume was also associated with worse performance on cognitive functioning in former American football players (β = -0.74 [95% CI, -1.35 to -0.13]; P = .04). These findings suggest that impaired perivascular brain clearance, as indicated by larger PVS volume, may contribute to the association observed between RHI exposure and neurodegeneration.

Associations Between Brain Metabolites Measured With MR Spectroscopy and Head Impacts in High School American Football Athletes.

While changes in brain metabolites after injury have been reported, relationships between metabolite changes and head impacts are less characterized. To investigate alterations in neurochemistry in high school athletes as a function of head impacts, concussion, and the use of a jugular vein compression (JVC) collar. Prospective controlled trial. A total of 284 male American football players, divided into JVC collar and noncollar groups; 215 included in final analysis (age = 15.9 ± 1.0 years; 114 in collar group). 3 Tesla/T1-weighted gradient echo, 1H point resolved spectroscopy, acquired between August and November 2018. Head impacts were quantified using accelerometers. Concussion was diagnosed by medical professionals for each team. Pre- to postseason differences in total N-acetylaspartate (tNAA), total choline (tCho), myo-inositol (myoI), and glutamate + glutamine (Glx), in primary motor cortex (M1) and anterior cingulate cortex (ACC), relative to total creatine (tCr), were determined. Group-wise comparisons were performed using Wilcoxon signed-rank, Friedman's, and Mann-Whitney U tests. Relationships between ∆metabolite/tCr and mean g-force were analyzed using linear regressions accounting for concussion and JVC collar. Significance was set at P ≤ 0.05. In participants without concussion, a significant decrease in tCho/tCr (0.233 ± 1.40 × 10-3 to 0.227 ± 1.47 × 10-7) and increase in Glx/tCr (1.60 ± 8.75 × 10-3 to 1.63 ± 1.08 × 10-2) in ACC were observed pre- to postseason. The relationship between ∆tCho/tCr in M1 and ACC and mean g-force from >80 g to >140 g differed significantly between participants with and without concussion (M1 β ranged from 3.9 × 10-3 to 2.1 × 10-3; ACC β ranged from 2.7 × 10-3 to 2.1 × 10-3). Posthoc analyses revealed increased tCho/tCr in M1 was positively associated with mean g-force >100 g (β = 3.6 × 10-3) and >110 g (β = 2.9 × 10-3) in participants with concussion. Significant associations between in ACC and mean g-force >110 g (β = -1.1 × 10-3) and >120 g (β = -1.1 × 10-3) were observed in the collar group only. Diagnosed concussion and the use of a JVC collar result in distinct neurochemical trends after repeated head impacts. 2 TECHNICAL EFFICACY: Stage 3.