American Football Players Research Articles

NFL Draft Prep Players Improve 40-Yard Run Times and Foot-Ground Kinetics

Introduction: Linear speed is a discriminant factor between drafted and undrafted American football players into the National Football League. Linear speed is influenced by foot-ground contact time and the magnitude of vertical ground reaction force. The aim of this study was to determine if foot-ground kinetics during speed running could be modified through participating in a 6-week NFL draft preparation camp. Methods: To evaluate foot-ground kinetics, 16 American football players ran on an instrumented treadmill for 5 seconds at 6.5 m/s. Linear speed was measured during a 40-yard (36.6 m) outdoor run. Pre- and post-camp linear speed times, stance-averaged vertical ground reaction forces (vGRF, kg/N), foot-ground contact time (msec), and vertical impulse (kg/N * s) were examined using paired t-tests, p<.05. Results: Linear speed times significantly improved [(pre, 4.8±0.2 vs. post, 4.6±0.2 sec), t(15)=13.8, p<.001)], and foot-ground contact time significantly decreased for the right limb [(pre, 177+3.2 vs. post, 168+2.2 ms), t(15)=2.21, p=.043]. Mean vertical impulse and stance-averaged GRF for both limbs remained unchanged, p>.05. Conclusions: Linear speed and selected foot-ground kinetics are modifiable in NFL draft prep players. Training appears to lower 40-yard run times and foot-ground contact time.

Cervical Spine CT Can Miss Fractures in American Football Players When Protective Equipment is in Place: A Cadaver Study.

Iatrogenic worsening of spinal injury can result in significant harm to American football players and complicate management when equipment is removed in the acute setting by inexperienced personnel. Spine imaging before removal of protective equipment mitigates this risk. There is no consensus regarding the ideal timing of equipment removal or whether current diagnostic imaging modalities are effective to detect such injuries without equipment removal. Prior data suggest that CT is a diagnostic modality for this purpose; however, radiologists' accuracy in detecting fractures in the presence of protective equipment requires additional study. (1) Does the introduction of American football equipment result in a significant reduction in sensitivity for cervical spine fracture detection? (2) Absent specific guidance as to parameters needed to establish diagnostic quality, can a radiologist determine whether such CTs are of diagnostic quality by subjectively relying on the ability to identify anatomic landmarks? A pendulum device was engineered to deliver a measured axial load to the crown of cadavers to produce a variety of cervical spine fractures in 13 cadaver specimens. The cadavers were then imaged using a standardized CT protocol first without and then with protective football equipment. The images were presented to three board-certified, fellowship-trained radiologists to (1) identify all fractures from the occiput to T1 and (2) subjectively assess the diagnostic quality of the resulting CTs. A sensitivity analysis was performed against a reference standard of fractures produced by the consensus of all radiologists in this study to determine whether there was any reduction in radiologists' ability to detect fractures once football equipment was in place. We found that CT scans obtained with football protective equipment in place resulted in lower sensitivity in diagnosing cervical spine injuries than CT scans obtained without pads. A total of 42 fractures were identified in the reference standard, allowing for a combined 126 possible fracture identifications between the three interpreters. Without football equipment, a combined 98 fractures were identified, whereas a combined 65 fractures were identified once the equipment was introduced. Overall, the sensitivity was reduced by 26% (52% [65 of 126] versus 78% [98 of 126] [95% CI 14.8% to 37.5%]; p < 0.001). Of the 78 total CT series imaged with football equipment, 92% (72 of 78) were considered to be of diagnostic quality. However, the study radiologists failed to identify 50% (53 of 105) of fractures present in those CT images. The sensitivity of cervical spine fracture detection using CT is diminished in the setting of protective American football equipment. Future studies in live subjects with cervical spine fracture may be warranted to support these conclusions. These findings contradict previous studies that determined CT to be a diagnostic imaging modality to image the cervical spine through equipment. Although the interpreting radiologists consistently deemed CTs performed in the presence of helmets and shoulder pads to have subjectively diagnostic quality, numerous fractures that had been detected in the absence of equipment were missed in their presence. Furthermore, this study established that subjective approval of the appearance of an imaging study based on the ability to recognize anatomic landmarks is insufficient to reliably determine the diagnostic quality of a CT study.

Do Americans Really Support Black Athletes Who Kneel During the National Anthem? Estimating the True Prevalence and Strength of Sensitive Racial Attitudes in the Context of Sport

Professional athletes in the United States have protested racism in various ways for decades. Kneeling during the national anthem became a prominent form of such activism, ever since American football player Colin Kaepernick popularized the practice in 2016. “Anthem protests” gained renewed attention after the police killing of George Floyd and nationwide unrest in the summer of 2020. This article explores whether public approval of those protests was weaker than scholars and journalists suggested, because survey respondents were reluctant to admit that they considered the protesters disrespectful. A list experiment confirms hidden opposition to anthem protests, especially among people of color, who may feel heightened pressure to support racialized protesters. A second experiment reveals that social desirability bias persists even after respondents hear reassurance that nobody will judge their views. These findings indicate that mainstream surveys misrepresent attitudes toward contemporary racial issues, and that anthem protests have yet to gain wide acceptance in the general U.S. population.

The effects of docosahexaenoic acid and eicosapentaenoic acid on biomarkers of sub‐concussive injury in National Collegiate Athletic Association Division 1 American football players

Participation in American football has been associated with repeated head impacts (RHI) and an increase in risk of concussive injury also called mild traumatic brain injury (mTBI). Elevated neurofilament light (NfL), a biomarker of axonal injury, has been shown to be a sensitive marker for both mTBI and sub-concussive brain injury in contact sports. Omega-3 polyunsaturated fatty acids, including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), have been reported to reduce inflammation, protecting against nerve damage, stimulating neuronal growth, and promoting recovery following head injury. Here we performed a randomized, placebo-controlled, double-blinded, parallel group design trial to determine the potential impact of DHA/EPA supplementation on serum NfL in National Collegiate Athletic Association (NCAA) Division I American football athletes (n=38). Players (both starters and nonstarters) were assigned to either 3.0 g/d DHA/EPA or placebo groups, and blood was sampled at baseline and throughout the football season from no contact conditioning to the last in-season scheduled game. DHA/EPA supplementation markedly increased plasma DHA levels from baseline at four time points (p<0.000001 at time point (T) 2; p<0.0001 at T3; p<0.001 at T4; and p<0.01 at T5). Additionally, serum NfL increased in all participants (starters and nonstarters) during conditioning and early season (p<0.001), and this upward trend continued in starters throughout the season (p<.05). There was no impact of DHA/EPA supplementation on serum NfL levels in either group tested. This study confirms results from previous studies which show an increased circulating NfL level in players who spent the greatest amount of time on the field in games (starters). However, it did not corroborate previous findings that DHA/EPA supplementation attenuates the increase in NfL levels in either group. Important limitations of this study include the small sample size and heterogeneous group of football players. This study supports the need for effective strategy to protect American football participants from brain injury.

Arthroscopic Soft Tissue Stabilization With Selective Augmentations for Traumatic Anterior Shoulder Instability in Competitive Collision Athletes

Background: Many surgeons prefer bony stabilization including Bristow or Latarjet procedures for shoulder instability in collision athletes, even though several potential complications have been reported. There has been a limited number of studies on the midterm outcomes of arthroscopic soft tissue stabilization for anterior shoulder instability in competitive collision athletes. Purpose: To assess the outcomes of arthroscopic soft tissue stabilization in combination with selective augmentation procedures for collision athletes with traumatic anterior shoulder instability Study Design: Case series; Level of evidence, 4. Methods: We retrospectively assessed rugby or American football players (<40 years old) who underwent arthroscopic Bankart or bony Bankart repair with selective augmentations (rotator interval closure and/or Hill-Sachs remplissage) for traumatic anterior shoulder instability between January 2012 and March 2017. Shoulders that required other bony procedures were excluded. Recurrence, complications, return to sport, and functional scores (Rowe score and Subjective Shoulder Value sports score) were investigated. Results: This study included 113 shoulders in 100 patients with a mean age of 20 years (range, 15-36 years) at surgery. Rotator interval closure was performed on 36 shoulders in addition to Bankart repair, and rotator interval closure and Hill-Sachs remplissage were performed on 77 shoulders. The mean follow-up period was 44 months (range, 24-72 months). Of the 113 shoulders, 4 (3.5%) experienced postoperative dislocation, but there were no complications. A total of 93 athletes (93%) attained complete or near complete preinjury sports activity levels. The mean Rowe score significantly improved from 36 (range, 10-75) at presurgery to 96 (range, 35-100; P = .003) at postsurgery. The mean Subjective Shoulder Value sports score significantly improved after surgery, from a mean preoperative score of 22 (range, 0-50) to a postoperative score of 92 (range, 64-100; P = .002). Conclusion: Our treatment strategy, where arthroscopic soft tissue stabilization was combined with selected augmentations, provided good clinical outcomes for competitive collision athletes in terms of low rates of recurrence and complication, a high rate of return to sports, and good shoulder function.

Contribution of American Football Uniforms to the Development of Exercise-Induced Hyperthermia: A Critically Appraised Topic

Clinical Scenario: Many American football players have died from exertional heatstroke, one of the leading causes of sudden death in athletes. These athletes are predisposed to exertional heatstroke, in part, because of their protective equipment. Few authors have systematically appraised the research to determine how much faster rectal temperature (Trec) increases when full American football uniforms generally consisting of a helmet, shoulder pads, jersey, pants with padding, socks, shoes, and underwear/compressions (PADS) are worn compared with no uniform so that clinicians can better plan and modify exercise sessions to prevent dangerous Trec (i.e., ≥40.5 °C). Clinical Question: How much faster does Trec increase when men wear a full American football uniform compared with workout clothing during exercise in the heat? Summary of Key Findings: The authors searched the literature for randomized controlled studies with PEDro scores &gt;6 that compared Trec of males wearing PADS to a control uniform during exercise under controlled laboratory conditions. In all four studies, Trec increased faster when PADS were worn during exercise (PADS = 0.052 ± 0.007 °C/min and control = 0.039 ± 0.009 °C/min). The average effect size across studies was 1.4 ± 0.5. Clinical Bottom Line: PADS increase Trec significantly faster than lesser uniform ensembles. Clinicians should factor in equipment and alterations in exercise duration and rest break frequency to help prevent dangerous Trec in American football players. Strength of Recommendation: Given the large effect size and controlled experimental study designs, there is strong evidence that wearing PADS during exercise results in faster increases in body core temperature.

Staying on the ball during COVID-19 pandemic: impact on training modalities in football players.

COVID-19 pandemic has affected worldwide sports competitions and training in both amateur and professional leagues. We thus aimed to investigate changes in different training modalities in elite and amateur football players following COVID-19 lockdown in March 2020. In this cross-sectional study, we applied a Likert Scale-based questionnaire with 20 items to quantify and classify time spent at standard training methods in 47 professional and 54 amateur football players from 12 Austrian clubs before and during lockdown. Additionally, McLean Score was calculated to assess perceived training fatigue. Weekly amount of training time at endurance exercises (cycling) increased in both professional (37.5 [IQR 46.5] min/week vs. 187.5 [IQR 127.5] min/week, P<0.001), and amateur players (0.0 [IQR 45.0] min/week vs. 37.5 [IQR 112.5] min/week, P=0.015) during COVID-19 lockdown. Time on diverse muscle strengthening workouts was significantly elevated in both cohorts. Total training time at ball declined for professionals (from 472.5 [IQR 150] min/week to 15.0 [IQR 112.5] min/week, P<0.001) and amateurs (from 337.5 [IQR 285] min/week to 0.0 [IQR 37.5] min/week, P<0.001). Video-guided training was intensified in both groups (P<0.001 each). Location shifted from football fields and gyms to home and outdoors. Overall McLean Score remained unchanged in amateurs (P=0.42) while elite players showed a trend towards an increase (P=0.056). COVID-19 lockdown compromised football training, especially training concepts with ball. Consequently, resulting changes in exercise loads and muscular burden might impact susceptibility for injuries and impair performances especially in amateur players, especially as they lacked training supervision and professional training plans. Minimum effective dose of training workload to maintain endurance- and neuromuscular-related performance parameters should be prescribed.

Neuroimaging Biomarkers of Chronic Traumatic Encephalopathy: Targets for the Academic Memory Disorders Clinic.

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with exposure to repetitive head impacts, such as those from contact sports. The pathognomonic lesion for CTE is the perivascular accumulation of hyper-phosphorylated tau in neurons and other cell process at the depths of sulci. CTE cannot be diagnosed during life at this time, limiting research on risk factors, mechanisms, epidemiology, and treatment. There is an urgent need for in vivo biomarkers that can accurately detect CTE and differentiate it from other neurological disorders. Neuroimaging is an integral component of the clinical evaluation of neurodegenerative diseases and will likely aid in diagnosing CTE during life. In this qualitative review, we present the current evidence on neuroimaging biomarkers for CTE with a focus on molecular, structural, and functional modalities routinely used as part of a dementia evaluation. Supporting imaging-pathological correlation studies are also presented. We targeted neuroimaging studies of living participants at high risk for CTE (e.g., aging former elite American football players, fighters). We conclude that an optimal tau PET radiotracer with high affinity for the 3R/4R neurofibrillary tangles in CTE has not yet been identified. Amyloid PET scans have tended to be negative. Converging structural and functional imaging evidence together with neuropathological evidence show frontotemporal and medial temporal lobe neurodegeneration, and increased likelihood for a cavum septum pellucidum. The literature offers promising neuroimaging biomarker targets of CTE, but it is limited by cross-sectional studies of small samples where the presence of underlying CTE is unknown. Imaging-pathological correlation studies will be important forthe development and validation of neuroimaging biomarkers of CTE.

Analyses of Countermovement Jump Performance in Time and Frequency Domains.

This study aimed to analyze counter-movement jump (CMJ) performance in time and frequency domains. Fortyfour Division I American football players participated in the study. Kinetic variables were collected from both dominant and non-dominant legs using two force plates. Normalized peak power, normalized net impulse, and normalized peak force significantly correlated with jump height (r = .960, r = .998, r = .725, respectively with p < .05). The mean frequency component was significantly correlated with CMJ performance (r = .355 with p < .05). The reliability of the frequency variables was higher than the time domain variables. Frequency domain variables showed weaker correlations with jump height compared with time domain variables. Frequency domain analysis provides frequency components, which represent the rate of energy transmission from the eccentric phase to the end of the push-off phase. Frequency component information may provide additional information for the analyses of CMJ performance for athletes.

Player age and initial helmet contact among American football players.

Concussions and chronic traumatic encephalopathy (CTE) related to professional football has received much attention within emergency care and sports medicine. Research suggests that some of this may be due to a greater likelihood of initial helmet contact (IHC), however this association has not been studied across all age groups. This study aims to investigate the association between player age and IHC in American football. Retrospective review of championship games between 2016 and 2018 at 6 levels of amateur tackle football as well as the National Football League (NFL). Trained raters classified plays as IHC using pre-specified criteria. A priori power analysis established the requisite impacts needed to establish non-inferiority of the incidence rate of IHC across the levels of play. Thirty-seven games representing 2912 hits were rated. The overall incidence of IHC was 16% across all groups, ranging from 12.6% to 18.9%. All but 2 of the non-NFL divisions had a statistically reduced risk of IHC when compared with the NFL, with relative risk ratios ranging from 0.55-0.92. IHC initiated by defensive participants were twice as high as offensive participants (RR 2.04, p < 0.01) while 6% [95% CI 5.4-7.2] of all hits were helmet-on-helmet contact. There is a high rate of IHC with a lower relative risk of IHC at most levels of play compared to the NFL. Further research is necessary to determine the impact of IHC; the high rates across all age groups suggests an important role for education and prevention.

The Relationship between Mental Readiness and Difficulty in Emotion Regulation of Amateur Football Players

This study aims to investigate the relationship between amateur football players’ mental readiness and difficulty in dealing with the level of emotion regulation. The study group consisted of 219 volunteer male athletes who actively played amateur league football in Bingol, Turkey during the 2018-2019 season. Along with a consideration of various demographic variables, the “Mental Readiness Scale” and the “Difficulty in Emotion Regulation Scale” have been used in this study. SPSS packaged software has been utilized for data analysis purposes. Descriptive statistics, Pearson Correlation and the One-Way ANOVA test have been utilized in the data analysis. According to the findings, a negative relationship has been determined between mental readiness and difficulty in emotion regulation on the part of the amateur football players. Furthermore, a statistically significant difference has been found between the variable of the football playing year and the total degree of mental readiness, mental preparation, cool-headedness and goals sub-dimensions (p&lt; .05). Moreover, another statistically significant difference has been determined between the variable working period with the current coach and the total degree of mental readiness, mental preparation and cool-headedness sub-dimensions. As a consequence, the results suggest that as the mental readiness levels of the amateur players taking part in the study increase, the difficulty they experience in emotion regulation decreases. Additionally, it has been found out that as the football playing year and working period with the current coach increases, the athletes’ mental readiness levels go up, and the level of difficulty with regard to emotion regulation decreases.

Analysis of Differences of Running Perfomances of Elite European and Latin American Football Players

This research is aimed to determine the differences in the racing performances of elite European and Latin American footballers. The research was conducted on a sample of N = 157 top football players, aged 19 to 35, who played all 90 minutes in the first round of the group stage of the competition at the 2018 World Cup. Respondents were classified into two groups, where group I (N = 103) consisted of football teams from Europe, and group II (N = 54), consisted of teams from Latin America. The obtained data showed that 8 out of 13 variables have the characteristic of heterogeneity with a higher value of variance than the arithmetic mean. The results of the T-test showed that only 4 of 13 variables had statistically significant differences. Footballers from European national teams are on average taller than Latin American footballers by just over 3 cm. European footballers had a 4% greater (p&gt; 0.05) total distance traveled, distance in the first and second half of the game than Latin American footballers.

Age at First Exposure to Tackle Football is Associated with Cortical Thickness in Former Professional American Football Players.

Younger age at first exposure (AFE) to repetitive head impacts while playing American football increases the risk for later-life neuropsychological symptoms and brain alterations. However, it is not known whether AFE is associated with cortical thickness in American football players. Sixty-three former professional National Football League players (55.5 ± 7.7years) with cognitive, behavioral, and mood symptoms underwent neuroimaging and neuropsychological testing. First, the association between cortical thickness and AFE was tested. Second, the relationship between clusters of decreased cortical thickness and verbal and visual memory, and composite measures of mood/behavior and attention/psychomotor speed was assessed. AFE was positively correlated with cortical thickness in the right superior frontal cortex (cluster-wise P value [CWP] = 0.0006), the left parietal cortex (CWP = 0.0003), and the occipital cortices (right: CWP = 0.0023; left: CWP = 0.0008). A positive correlation was found between cortical thickness of the right superior frontal cortex and verbal memory (R = 0.333, P = 0.019), and the right occipital cortex and visual memory (R = 0.360, P = 0.012). In conclusion, our results suggest an association between younger AFE and decreased cortical thickness, which in turn is associated with worse neuropsychological performance. Furthermore, an association between younger AFE and signs of neurodegeneration later in life in symptomatic former American football players seems likely.

Differences in trunk range of motion for various flexibility protocol types, particularly in quarterbacks wearing rib protectors

Summary Background It is unclear how rib protectors may affect trunk mobility in American football players. The purposes of the study were: 1) to determine which flexibility protocol (active-assisted, maximal-speed, self-selected) exhibits the highest range of motion for trunk lateral flexion and axial rotation and 2) to determine the effect of rib protectors (hard-rib and soft-rib protectors and control: compression shirt only) on trunk range of motion. Methods Eleven male participants with competitive quarterback experience were recruited. Participants were instructed to rotate the trunk in the lateral flexion and axial rotation directions during each flexibility protocol and rib protector condition. The lower-thoracic range of motion were measured. Results Two-way repeated measures ANOVA (flexibility protocol by rib protector) demonstrated significant main effect of flexibility protocol for lateral flexion, but not axial rotation. The range of motion during self-selected protocol was significantly greater than maximal-speed protocol by approximately 7° (p = .009). Conclusions Self-selected and maximal-speed protocol produced the highest lateral flexion and axial rotation range of motion, respectively, and can be used to test the influence of rib protectors and potentially other sports equipment on thoraco-lumbar range of motion. Additionally, rib protectors likely do not affect trunk range of motion needed to throw long-distance passes or other movements as performed by football quarterbacks.

Causes and differentiation of injuries depending on the positions taken on the pitch among American Football players in Poland.

American Football (AF) players are assigned to positions by specific abilities and responsible for different tasks on the field; this may result into wide differentiation in experienced injuries. The aim of this study was to analyze the causes of injuries and their differentiation depending on the position on the pitch. Original questionnaire was used to investigate 150 Polish amateur AF players who had suffered from 189 injuries. The questionnaire detailed the following positions: offensive line (OL), defensive line (DL), quarterback (QB), running back (RB), wide receiver (WR), linebacker (LB), defensive backs (DB). The results were statistically analyzed by SofaStas v. 1.4.5 (SOFA Statistics, San Jose, CA, USA) and then had been interpreted. Over 90% of all investigated AF players had self-reported injury history with the injury rate 1.27 injury per player. No statistically significant relationship was stated between position on the pitch and the occurrence rate, type and location of the injury. Significant relationship (P=0.030) was stated between the injury circumstances and position on the pitch - QB were mostly injured in collision with opponent, OL in direct sport fight while WR and RB due to a fall. Occurrence and type of injuries in AF players does not depend on position on the pitch in AF. Relationship between the injury location or injury circumstances and position on the pitch requires further studies. The most common location of injury is the knee joint, and the most common type of injury is sprain while the most common causes of injury were collision with opponent and direct sport fight.

Disparate Associations of Years of Football Participation and a Metric of Head Impact Exposure with Neurobehavioral Outcomes in Former Collegiate Football Players.

Years of sport participation (YoP) is conventionally used to estimate cumulative repetitive head impacts (RHI) experienced by contact sport athletes. The relationship of this measure to other estimates of head impact exposure and the potential associations of these measures with neurobehavioral functioning are unknown. We investigated the association between YoP and the Head Impact Exposure Estimate (HIEE), and whether associations between the two estimates of exposure and neurobehavioral functioning varied. Former American football players (N = 58; age = 37.9 ± 1.5 years) completed in-person evaluations approximately 15 years following sport discontinuation. Assessments consisted of neuropsychological assessment and structured interviews of head impact history (i.e., HIEE). General linear models were fit to test the association between YoP and the HIEE, and their associations with neurobehavioral outcomes. YoP was weakly correlated with the HIEE, p = .005, R2 = .13. Higher YoP was associated with worse performance on the Symbol Digit Modalities Test, p = .004, R2 = .14, and Trail Making Test-B, p = .001, R2 = .18. The HIEE was associated with worse performance on the Delayed Recall trial of the Hopkins Verbal Learning Test-Revised, p = .020, R2 = .09, self-reported cognitive difficulties (Neuro-QoL Cognitive Function), p = .011, R2 = .10, psychological distress (Brief Symptom Inventory-18), p = .018, R2 = .10, and behavioral regulation (Behavior Rating Inventory of Executive Function for Adults), p = .017, R2 = .10. YoP was marginally associated with the HIEE, a comprehensive estimate of head impacts sustained over a career. Associations between each exposure estimate and neurobehavioral functioning outcomes differed. Findings have meaningful implications for efforts to accurately quantify the risk of adverse long-term neurobehavioral outcomes potentially associated with RHI.

Positional Differences in Pre-Season Scrimmage Performance of Division I Collegiate Football Players.

This study aimed to describe the physical demands of American football players using novel performance analysis techniques. Heart rate (HR) and accelerometer-based activity levels were observed across two pre-season scrimmages in 23 Division I collegiate football players (age: 19 ± 1 y, height: 1.90 ± 0.06 m, weight: 116.2 ± 19.4 kg). Data were analyzed using a MATLAB program and inter-rater reproducibility assessed using inter-class correlations (ICC). Players were analyzed by side (offense/defense) and position (skill/non-skill). Performance variables assessed in bursts of activity included burst duration, HRmean and HRmax (bpm), and mean activity (vector magnitude units [vmu]). Exercise intensity was categorized as time spent in % HRmax in 5% increments. The burst duration (8.1±3.9 min, ICC = 0.72), HRmean (157 ± 12 bpm, ICC = 0.96) and mean activity (0.30 ± 0.05 vmu, ICC = 0.86) were reproducible. HRmean (p = 0.05) and HRmax (p = 0.001) were greater on defense. Offense spent more time at 65–70% HRmax (p = 0.01), 70–75% HRmax (p = 0.02) while defense spent more time 90–95% HRmax and ≥95% HRmax (p = 0.03). HRmean (p = 0.70) and HRpeak (p = 0.80) were not different between positions across both sides. Skilled players demonstrated greater mean activity (p = 0.02). The sport-specific analysis described HR and activity level in a reproducible manner. Automated methods of assessing HR may be useful in training and game time performance but ultimately provides support to coaching decision making.

Player position in American football influences the magnitude of mechanical strains produced in the location of chronic traumatic encephalopathy pathology: A computational modelling study

American football players are frequently exposed to head impacts, which can cause concussions and may lead to neurodegenerative diseases such as chronic traumatic encephalopathy (CTE). Player position appears to influence the risk of concussion but there is limited work on its effect on the risk of CTE. Computational modelling has shown that large brain deformations during head impacts co-localise with CTE pathology in sulci. Here we test whether player position has an effect on brain deformation within the sulci, a possible biomechanical trigger for CTE. We physically reconstructed 148 head impact events from video footage of American Football games. Players were separated into 3 different position profiles based on the magnitude and frequency of impacts. A detailed finite element model of TBI was then used to predict Green-Lagrange strain and strain rate across the brain and in sulci. Using a one-way ANOVA, we found that in positions where players were exposed to large magnitude and low frequency impacts (e.g. defensive back and wide receiver), strain and strain rate across the brain and in sulci were highest. We also found that rotational head motion is a key determinant in producing large strains and strain rates in the sulci. Our results suggest that player position has a significant effect on impact kinematics, influencing the magnitude of deformations within sulci, which spatially corresponds to where CTE pathology is observed. This work can inform future studies investigating different player-position risks for concussion and CTE and guide design of prevention systems.

NCAA Division I American football players with sickle cell trait have altered hematological responses and hydration status

Sickle cell trait (SCT) is a risk factor of collapse and sudden death in athletes. We conducted a longitudinal study to determine the hematological responses and hydration status in NCAA Division I American football players with SCT. The study took place over 2 years with 6 SCT and 6 position-matched controls (CON) in year 1; and 4 SCT and 4 CON in year 2. In year 2, three of the four SCT players were recruited and re-enrolled with new position-matched controls (total sample data = 10 SCT and 10 CON). Blood samples were taken at three visits: pre-camp, post-camp, and post-season to examine hemoglobin variants, complete blood counts, and chemistry panel 26. Hydration status was assessed by measuring body weight change, urine specific gravity, and urine and sweat electrolyte concentrations during the pre-season training camp. All SCT players were confirmed to have SCT (HbS = 37.9 ± 2.4%) and had greater red cell distribution width (RDW) compared to CON across all visits. Serum uric acid was higher in SCT (7.3 ± 1.0 mg/dL) compared to CON (6.1 ± 0.6 mg/dL; p = 0.001). Furthermore, serum creatine kinase levels were greater in SCT (1617.0 ± 1034.8 IU/L) at pre-camp compared to CON (1037.4 ± 602.8 IU/L; p = 0.03). SCT players exhibited lower pre- and post-practice urine electrolytes and urine specific gravity (SCT pre: 1.019 ± 0.005 vs. CON pre: 1.026 ± 0.008 p < 0.001; SCT post: 1.020 ± 0.005 vs. CON post: 1.030 ± 0.008 p < 0.01), whereas sweat sodium concentrations were higher in SCT players (55.4 ± 13.6 mmol/L) compared to CON (45.5 ± 10.6 mmol/L; p < 0.001). Given the evidence, greater uric acid and CPK levels in SCT players compared to CON may be an early indicator of altered kidney function and muscle damage, which could be added into NCAA guidelines for surveillance among SCT players. Consistent education and reinforcement of the importance of adequate fluid balance during exercise are critical for both SCT and CON players.

Parachute Resistance Training: A Method to Improve the Running Speed of Football Players

The problem raised is the absence of data on the implementation of prisoner parachute-assisted training methods that can increase the short running speed of amateur football players. This study aims to determine the effect of parachute resistance assisted training methods on running speed. This type of research is quantitative with a quasi-experimental research method with the modified pre-test-post-test group design. The subjects of this study were 10 male amateur football players aged 18-20 years. The test instrument in this study is to measure the running speed using the 30 meters sprint test. Data were analyzed using t-test paired sample t-test at a significance level of 5%. The results of data analysis showed that the parachute resistance assisted training method had an effect on running speed (sig value = 0.000). Thus, the parachute resistance assisted training method is suitable to be applied to increase the running speed of amateur football players. This research can be further developed by increasing the number of samples and applied to professional football players.