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Purpose: Limited data from former National Football League (NFL) players suggest that obstructive sleep apnea (OSA) may be highly prevalent after retirement. It remains unclear whether the high prevalence of OSA in retired players is comparable to nonathletes. This retrospective analysis compared sleep apnea (SA) risk in retired NFL players to a community cohort (CARDIA Sleep study), and examined associations between SA risk and cardiovascular risk factors, including subclinical atherosclerosis., Materials and Methods: Retired NFL players (n=122) were matched to CARDIA Sleep participants by age ±2 years (range 37-55 years), body mass index ±2 kg/m 2 , race, and male sex. Participants underwent electron-beam computed tomography to measure coronary artery calcium (CAC) and completed the Berlin Questionnaire to determine SA risk. The presence of CAC was defined as an Agatston score >0., Results: Retired NFL players had a greater prevalence of high SA risk than the matched CARDIA Sleep participants (27% vs 11.5%, P =0.002). Compared to the CARDIA Sleep participants, retired players were less likely to smoke, and had higher blood pressure, lower fasting glucose levels, and higher cholesterol levels. However, there was no difference in the prevalence of detectable CAC (30% vs 30%, P =1). In both players and the community cohort, SA risk was not significantly associated with CAC after controlling for age, race, and body mass index., Conclusion: Retired NFL players have a greater prevalence of high SA risk but similar prevalence of CAC compared with a well-matched community cohort., Competing Interests: Disclosure The authors report no conflicts of interest in this work.

Previous findings suggest that professional American football players have higher blood pressures (BP) and a higher prevalence of pre-hypertension and hypertension than the general population. We sought to determine whether race is associated with differences in BP and prevalence of pre-hypertension and hypertension among a large sample of professional football players. BP was measured at 2009 team mini-camps for 1484 black (n = 1007) and white (n = 477) players from 27 National Football League (NFL) teams. Players were categorized into three position groups based on body mass index (BMI). There was no racial difference in mean systolic or diastolic BP in any of the three position groups. There were no racial differences in prevalence of hypertension (99 [9.8%] black players vs. 39 [8.2%] white players; P = .353) or pre-hypertension (557 [55.3%] black players vs. 264 [55.3%] white players; P = 1.0). Contrary to findings in the general population, BP and prevalence of pre-hypertension/hypertension did not vary with race in a large population of active NFL players., (Copyright © 2015 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.)

Two American football players on the same team were diagnosed with methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections on the same day. Our investigation, including whole genome sequencing, confirmed that players did not transmit MRSA to one another nor did they acquire the MRSA from a single source within the training facility.

Background: Positions, signs, symptoms, and medical management of National Football League players with concussions involving 7 or more days out (7+) from play were compared for two 6-year study periods (2002-2007 vs 1996-2001)., Hypothesis: More players were held out 7+ days in the 2002-2007 period without significant difference in concussion signs and symptoms., Study Design: Cohort., Methods: From 1996 through 2007, National Football League team physicians reported concussion signs and symptoms, medical action taken, and follow-up management., Results: During the 2002-2007 period, 143 (16.7%) and 33 (3.86%) concussed players were out 7+ days and 21+ days, respectively, compared with 73 (8.2%) and 7 (0.79%) in the 1996-2001 period, a significant difference (z = 5.39, P < .01). The positions with the highest fraction of 7+ days out were the quarterback (24.5% vs 16.1%), linebacker (19.7% vs 4.6%), and wide receiver (19.5% vs 8.2%) in the later versus earlier period. The player positions with the highest odds for being out 7+ days were quarterback (odds ratio = 1.80 vs 4.02), linebacker (odds ratio = 1.28 vs 0.65), and wide receiver (odds ratio = 1.25 vs 1.15). The highest incidence of 7+ days out occurred after passing plays (32.2% vs 37.0%), followed by kickoffs (18.9% vs 21.9%). The majority of players with 7+ days out were removed from the game on the day of injury (74.8% vs 72.6%); a smaller fraction were returned to play on the day of injury in the later 6 years (3.5% vs 6.8%)., Conclusions: The positions with the highest odds for being out 7+ days with concussion were quarterbacks, linebackers, and wide receivers. In the more recent 6-year period, more players were managed conservatively by being held out 7+ days, even though the signs and symptoms of their concussions were similar to those in the earlier period.

Background: Repeat concussion is an important issue in the National Football League (NFL). An initial description of repeat injuries was published for 6 years (1996-2001)., Hypothesis: The characteristics and frequency of repeat concussion in the NFL have not changed in the subsequent 6 years (2002-2007)., Study Design: Case control., Methods: From 1996 to 2007, concussions were reported using a standardized form documenting signs and symptoms, loss of consciousness and medical action taken. Data on repeat concussions were analyzed for the 12 years and compared between the 2 periods., Results: In 2002-2007, 152 players had repeat concussions (vs 160 in 1996-2001); 44 had 3+ head injuries (vs 52). The positions most often associated with repeat concussion in 2002-2007 were the defensive secondary, kick unit, running back, and linebacker. The odds for repeat concussion were elevated for wide receivers, tight ends, and linebackers but lower than in the earlier period. During 2002-2007, over half of players with repeat concussion were removed from play, and fewer immediately returned (vs 1996-2001). The average duration between concussions was 1.25 years for 2002-2007 and 1.65 years for the 12-year period. Over 12 years, 7.6% of all repeat concussions occurred within 2 weeks of the prior concussion., Conclusions: The defensive secondary, kick unit, running back, and linebacker have the highest incidence of repeat concussion. During 2002-2007, more than half of players with repeat concussion were removed from play, and only a fraction immediately returned. Although concussion was managed more conservatively by team physicians in the recent 6 years, repeat concussions occurred at similar rates during both periods.

Background: Concussion in the National Football League (NFL) remains an important issue. An initial description of the injury epidemiology involved 6 years from 1996 to 2001., Hypothesis: The increased attention to concussions may have resulted in team physicians being more conservative in treating players in recent years., Study Design: Two consecutive 6-year periods (1996-2001 and 2002-2007) were compared to determine changes in the circumstances associated with the injury, the patterns of signs and symptoms, and the players' time loss from participation in the NFL., Methods: During 2002-2007, concussions were recorded by NFL team physicians and athletic trainers using the same standardized reporting form used from 1996 to 2001. Player position, type of play, concussion signs and symptoms, loss of consciousness, and medical action taken were recorded., Results: There were 0.38 documented concussions per NFL game in 2002-2007-7.6% lower than the 0.42 in the earlier period (1996-2001). The injury rate was lower in quarterbacks and wide receivers but significantly higher in tight ends during the second 6 years. The most frequent symptoms were headaches and dizziness; the most common signs were problems with information processing and immediate recall. During 2002-2007, a significantly lower fraction of concussed players returned to the same game, and more were removed from play. Most concussed players (83.5%) returned to play in < 7 days; the percentage decreased to 57.4% with loss of consciousness. The number of players returning in < 7 days was 8% lower during 2002-2007 and 25% lower for those with loss of consciousness., Conclusion: The most recent 6 years of NFL concussion data show a remarkable similarity to the earlier period. However, there was a significant decrease in the percentage of players returning to the same game, and players were held out of play longer., Clinical Relevance: There was a more conservative management of concussion in NFL players from 2002 to 2007 even though the clinical signs and symptoms remained similar to the earlier 6-year period.

Context: Concern exists about the cardiovascular health implications of large size among professional football players and those players who aspire to professional status., Objectives: To assess cardiovascular disease (CVD) risk factors in active National Football League (NFL) players and to compare these findings with data from the Coronary Artery Risk Development in Young Adults (CARDIA) study., Design, Setting, and Participants: A cross-sectional study of 504 active, veteran football players from a convenience sample of 12 NFL teams at professional athletic training facilities between April and July 2007. Data were compared with men of the same age in the general US population (CARDIA study, a population-based observational study of 1959 participants aged 23 to 35 years recruited in 1985-1986)., Main Outcome Measures: Prevalence of CVD risk factors (hypertension, dyslipidemia, glucose intolerance, and smoking)., Results: The NFL players were less likely to smoke when compared with the CARDIA group (0.1% [n = 1]; 95% confidence interval [CI], 0%-1.4%; vs 30.5% [n = 597]; 95% CI, 28.5%-32.5%; P < .001). Despite being taller and heavier, NFL players had significantly lower prevalence of impaired fasting glucose (6.7% [n = 24]; 95% CI, 4.6%-8.7%; vs 15.5% [n = 267]; 95% CI, 13.8%-17.3%; P < .001). The groups did not differ in prevalence of high total cholesterol and low-density lipoprotein cholesterol (LDL-C), low high-density lipoprotein cholesterol (HDL-C), or high triglycerides. Hypertension (13.8% [n = 67]; 95% CI, 11.0%-16.7%; vs 5.5% [n = 108]; 95% CI, 4.6%-6.6%) and prehypertension (64.5% [n = 310]; 95% CI, 58.3%-70.7%; vs 24.2% [n = 473]; 95% CI, 22.3%-26.1%) were significantly more common in NFL players than in the CARDIA group (both P < .001). Large size measured by body mass index (BMI) was associated with increased blood pressure, LDL-C, triglycerides, and fasting glucose, and decreased HDL-C., Conclusions: Compared with a sample of healthy young-adult men, a sample of substantially larger NFL players had a lower prevalence of impaired fasting glucose, less reported smoking, a similar prevalence of dyslipidemia, and a higher prevalence of hypertension. Increased size measured by BMI was associated with increased CVD risk factors in this combined population.

The authors' studies have yielded a great deal of data regarding the biomechanics of head injury and the clinical picture of mild traumatic brain injury (MTBI) in the National Football League (NFL). The research has demonstrated the link between the effects of biomechanical forces on the brain and the clinical symptomatology of the concussed players. New insights into the mechanisms of injury are leading to new ways of protecting football players from the effects of MTBI. The clinical data validate the effectiveness of the current NFL physician approach to the evaluation and treatment of the player who sustains MTBI. There are still many more questions to answer and much more knowledge to be gained from continuing research in this area.

The authors' studies have yielded a great deal of data regarding the biomechanics of head injury and the clinical picture of mild traumatic brain injury (MTBI) in the National Football League (NFL). The research has demonstrated the link between the effects of biomechanical forces on the brain and the clinical symptomatology of the concussed players. New insights into the mechanisms of injury are leading to new ways of protecting football players from the effects of MTBI. The clinical data validate the effectiveness of the current NFL physician approach to the evaluation and treatment of the player who sustains MTBI. There are still many more questions to answer and much more knowledge to be gained from continuing research in this area.

Objective: Impacts causing concussion in professional football were simulated in laboratory tests to determine collision mechanics. This study focuses on the biomechanics of concussion in the struck player., Methods: Twenty-five helmet impacts were reconstructed using Hybrid III dummies. Head impact velocity, direction, and helmet kinematics-matched game video. Translational and rotational accelerations were measured in both players' heads; 6-axis upper neck responses were measured in all striking and five struck players. Head kinematics and biomechanics were determined for concussed players. Head displacement, rotation, and neck loads were determined because finite element analysis showed maximum strains occurring in the midbrain after the high impact forces. A model was developed of the helmet impact to study the influence of neck strength and other parameters on head responses., Results: The impact response of the concussed player's head includes peak accelerations of 94 +/- 28 g and 6432 +/- 1813 r/s2, and velocity changes of 7.2 +/- 1.8 m/s and 34.8 +/- 15.2 r/s. Near the end of impact (10 ms), head movement is only 20.2 +/- 6.8 mm and 6.9 +/- 2.5 degrees. After impact, there is rapid head displacement involving a fourfold increase to 87.6 +/- 21.2 mm and 29.9 +/- 9.5 degrees with neck tension and bending at 20 ms. Impacts to the front of the helmet, the source of the majority of National Football League concussions, cause rotation primarily around the z axis (superior-inferior axis) because the force is forward of the neck centerline. This twists the head to the right or left an average of 17.6 +/- 12.7 degrees, causing a moment of 17.7 +/- 3.3 Nm and neck tension of 1704 +/- 432 N at 20 ms. The head injury criterion correlates with concussion risk and is proportional to deltaV(4)/d(1.5) for half-sine acceleration. Stronger necks reduce head acceleration, deltaV, and displacement. Even relatively small reductions in deltaV have a large effect on head injury criterion that may reduce concussion risks because changes in deltaV change head injury criterion through the 4th power., Conclusion: This study addresses head responses causing concussion in National Football League players. Although efforts are underway to reduce impact acceleration through helmet padding, further study is needed of head kinematics after impact and their contribution to concussion, including rapid head displacement, z-axis rotation, and neck tension up to the time of maximum strain in the midbrain. Neck strength influences head deltaV and head injury criterion and may help explain different concussion risks in professional and youth athletes, women, and children.

PIn 1994 the National Football League (NFL) initiated a comprehensive clinical and biomechanical research study of mild traumatic brain injury (TBI), a study that is ongoing. Data on mild TBIs sustained between 1996 and 2001 were collected and submitted by NFL team physicians and athletic trainers, and these data were analyzed by the NFL's Committee on Mild Traumatic Brain Injury. At the same time, analysis of game videos was performed for on-field mild TBIs to quantify the biomechanics involved and to develop means to improve the understanding of these injuries so that manufacturers could systematically improve and update their head protective equipment. The findings and analysis of the Committee have been presented in a series of articles in Neurosurgery.

Objective: The performance of five newer helmets was compared with the baseline VSR-4 helmet in 10 reconstructed cases of National Football League (NFL) collisions causing concussion. The laboratory reconstructions were conducted to determine changes in concussion risk with newer football helmets., Methods: In 60 laboratory tests, translational and rotational head accelerations were measured in the striking and struck players represented by Hybrid III dummies. Six-axis upper neck loads and moments were measured in five cases with the struck player and five with the striking player. Biomechanical responses and concussion risks were evaluated for each collision to determine changes with newer helmet designs., Results: Thirty-two out of 50 reconstructed cases showed greater than 10% reduction in severity index with newer helmets compared with the VSR-4; four cases increased. The average reduction in concussion risk with newer helmets was 10.8% (range, 6.9-16.7%) based on severity index. The reduction was 9.7% (range, 6.5-13.9%) based on translational acceleration and 18.9% (range, 10.6-23.4%) with rotational acceleration. Neck responses in the struck player showed a general reduction in moment and force with newer helmets., Conclusion: With newer football helmets, there was a trend toward 10 to 20% lower risks of concussion in reconstructed National Football League game collisions. However, a few designs and cases showed increased responses. The evaluation of football helmets to the proposed National Operating Committee on Standards for Athletic Equipment concussion standard should lead to more uniform reductions in concussion risk with future football helmets.

Objective: Acute recovery from concussion (mild traumatic brain injury) is assessed in samples of NFL and high school athletes evaluated within days of injury., Methods: All athletes were evaluated within days of injury using a computer-based neuropsychological test and symptom inventory protocol. Test performance was compared to preinjury baseline levels of a similar but not identical group of athletes who had undergone preseason testing. Statistical analyses were completed using Multivariate Analysis of Variance (MANOVA)., Results: NFL athletes demonstrated a rapid neuropsychological recovery. As a group, NFL athletes returned to baseline performance in a week with the majority of athletes having normal performance two days after injury. High school athletes demonstrated a slower recovery than NFL athletes., Conclusion: Computer-based neuropsychological testing was used within the overall medical evaluation and care of NFL athletes. As found in a prior study using more traditional neuropsychological testing, NFL players did not demonstrate decrements in neuropsychological performance beyond one week of injury. High school players demonstrated more prolonged neuropsychological effects of concussion.

Objective: National Football League (NFL) concussions occur at an impact velocity of 9.3 +/- 1.9 m/s (20.8 +/- 4.2 mph) oblique on the facemask, side, and back of the helmet. There is a need for new testing to evaluate helmet performance for impacts causing concussion. This study provides background on new testing methods that form a basis for supplemental National Operating Committee on Standards for Athletic Equipment (NOCSAE) helmet standards., Methods: First, pendulum impacts were used to simulate 7.4 and 9.3 m/s impacts causing concussion in NFL players. An instrumented Hybrid III head was helmeted and supported on the neck, which was fixed to a sliding table for frontal and lateral impacts. Second, a linear pneumatic impactor was used to evaluate helmets at 9.3 m/s and an elite impact condition at 11.2 m/s. The upper torso of the Hybrid III dummy was used. It allowed interactions with shoulder pads and other equipment. The severity of the head responses was measured by a severity index, translational and rotational acceleration, and other biomechanical responses. High-speed videos of the helmet kinematics were also recorded. The tests were evaluated for their similarity to conditions causing NFL concussions. Finally, a new linear impactor was developed for use by NOCSAE., Results: The pendulum test closely simulated the conditions causing concussion in NFL players. Newer helmet designs and padding reduced the risk of concussion in 7.4 and 9.3 m/s impacts oblique on the facemask and lateral on the helmet shell. The linear impactor provided a broader speed range for helmet testing and more interactions with safety equipment. NOCSAE has prepared a draft supplemental standard for the 7.4 and 9.3 m/s impacts using a newly designed pneumatic impactor. No helmet designs currently address the elite impact condition at 11.2 m/s, as padding bottoms out and head responses dramatically increase., Conclusions: The proposed NOCSAE standard is the first to address helmet performance in reducing concussion risks in football. Helmet performance has improved with thicker padding and fuller coverage by the shell. However, there remains a challenge for innovative designs that reduce risks in the 11.2 m/s elite impact condition.

Objective: This study addresses impact biomechanics from boxing punches causing translational and rotational head acceleration. Olympic boxers threw four different punches at an instrumented Hybrid III dummy and responses were compared with laboratory-reconstructed NFL concussions., Methods: Eleven Olympic boxers weighing 51 to 130 kg (112-285 lb) delivered 78 blows to the head of the Hybrid III dummy, including hooks, uppercuts and straight punches to the forehead and jaw. Instrumentation included translational and rotational head acceleration and neck loads in the dummy. Biaxial acceleration was measured in the boxer's hand to determine punch force. High-speed video recorded each blow. Hybrid III head responses and finite element (FE) brain modeling were compared to similarly determined responses from reconstructed NFL concussions., Results: The hook produced the highest change in hand velocity (11.0 +/- 3.4 m/s) and greatest punch force (4405 +/- 2318 N) with average neck load of 855 +/- 537 N. It caused head translational and rotational accelerations of 71.2 +/- 32.2 g and 9306 +/- 4485 r/s. These levels are consistent with those causing concussion in NFL impacts. However, the head injury criterion (HIC) for boxing punches was lower than for NFL concussions because of shorter duration acceleration. Boxers deliver punches with proportionately more rotational than translational acceleration than in football concussion. Boxing punches have a 65 mm effective radius from the head cg, which is almost double the 34 mm in football. A smaller radius in football prevents the helmets from sliding off each other in a tackle., Conclusion: Olympic boxers deliver punches with high impact velocity but lower HIC and translational acceleration than in football impacts because of a lower effective punch mass. They cause proportionately more rotational acceleration than in football. Modeling shows that the greatest strain is in the midbrain late in the exposure, after the primary impact acceleration in boxing and football.

Objective: Brain responses from concussive impacts in National Football League football games were simulated by finite element analysis using a detailed anatomic model of the brain and head accelerations from laboratory reconstructions of game impacts. This study compares brain responses with physician determined signs and symptoms of concussion to investigate tissue-level injury mechanisms., Methods: The Wayne State University Head Injury Model (Version 2001) was used because it has fine anatomic detail of the cranium and brain with more than 300,000 elements. It has 15 different material properties for brain and surrounding tissues. The model includes viscoelastic gray and white brain matter, membranes, ventricles, cranium and facial bones, soft tissues, and slip interface conditions between the brain and dura. The cranium of the finite element model was loaded by translational and rotational accelerations measured in Hybrid III dummies from 28 laboratory reconstructions of NFL impacts involving 22 concussions. Brain responses were determined using a nonlinear, finite element code to simulate the large deformation response of white and gray matter. Strain responses occurring early (during impact) and mid-late (after impact) were compared with the signs and symptoms of concussion., Results: Strain concentration "hot spots" migrate through the brain with time. In 9 of 22 concussions, the early strain "hot spots" occur in the temporal lobe adjacent to the impact and migrate to the far temporal lobe after head acceleration. In all cases, the largest strains occur later in the fornix, midbrain, and corpus callosum. They significantly correlated with removal from play, cognitive and memory problems, and loss of consciousness. Dizziness correlated with early strain in the orbital-frontal cortex and temporal lobe. The strain migration helps explain coup-contrecoup injuries., Conclusion: Finite element modeling showed the largest brain deformations occurred after the primary head acceleration. Midbrain strain correlated with memory and cognitive problems and removal from play after concussion. Concussion injuries happen during the rapid displacement and rotation of the cranium, after peak head acceleration and momentum transfer in helmet impacts.

Objective: Concussive impacts in professional football were simulated in laboratory tests to determine the collision mechanics resulting in injury to the struck player and the biomechanics of the striking players, who were not concussed or neck-injured in the tackle., Methods: Twenty-seven helmet-to-helmet collisions were reconstructed in laboratory tests using Hybrid III dummies. The head impact velocity, direction, and kinematics matched game video. Translational and rotational head accelerations and six-axis upper neck loads and moments were used to evaluate how the striking player delivered the concussive blow. The neck injury criterion, Nij, was calculated to assess neck injury risks in the striking player., Results: The time-averaged impact force reached 6372 +/- 2486 N at 7.2 milliseconds because of 46.8 +/- 21.7 g head acceleration and 3624 +/- 1729 N neck compression force in the striking player. Fifty-seven percent of the load was contributed by neck compression. The striking players had their heads down and lined up the impact axis through their necks and torsos. This allowed momentum transfer with minimal neck bending and increased the effective mass of the striking player to 1.67 times that of the struck player at peak load. The impact caused 94.3 +/- 27.5 g head acceleration in the concussed players and 67.9 +/- 14.5 g without concussion (t = 2.06, df = 25, P = 0.025). The striking player's Nij was greater than tolerance in 9 of 27 cases by exceeding the 4000 N neck compression limit. For these cases, the average neck compression force was 6631 +/- 977 N (range, 5210-8194 N). Nij was 1.25 +/- 0.16 for eight cases above the tolerance Nij = 1.0., Conclusion: In the NFL, striking players line up their heads, necks, and torsos to deliver maximum force to the other player in helmet-to-helmet impacts. The concussive force is from acceleration of the striking player's head and torso load through the neck. Even though neck responses exceeded tolerances, no striking player experienced neck injury or concussion. A head-up stance at impact would reduce the torso inertial load in the collision and the risk of concussion in the struck player.

Objective: A 6-year study was conducted to determine the signs, symptoms, and outcome of players who were concussed and either returned immediately or were rested and returned to the same game in the National Football League (NFL)., Methods: From 1996 to 2001, concussions were recorded by NFL teams by use of a special standardized reporting form filled out by team physicians. Signs and symptoms were grouped by general symptoms, somatic complaints, cranial nerve effects, cognition problems, memory problems, and unconsciousness. Action taken after concussion was recorded for 887 patients., Results: There were 135 players (15.2%) who returned immediately and 304 (34.3%) who rested and returned to the same game after concussion. There were few differences by player position or team activity about the injury or action taken. However, the mean number of signs and symptoms progressively increased from those who returned immediately (1.52), rested and returned to play (2.07), were removed from play (3.51), or were hospitalized (6.55). Immediate recall problems (odds ratio [OR], 1.93; confidence interval [CI], 1.26-2.94), memory problems (OR, 1.52; CI, 1.06-2.19), and the number of signs and symptoms (OR, 1.39; CI, 1.25-1.55) were predictive of removal from play or hospitalization. There was no statistical association between return to play in the same game and a subsequent concussion or a more serious concussion involving 7+ days out., Conclusion: Players who are concussed and return to the same game have fewer initial signs and symptoms than those removed from play. Return to play does not involve a significant risk of a second injury either in the same game or during the season. The current decision-making of NFL team physicians seems appropriate for return to the game after a concussion, when the player has become asymptomatic and does not have memory or cognitive problems.

Objective: The National Football League (NFL) neuropsychological testing program is reviewed, and neuropsychological test data are presented on various samples of NFL athletes who sustained concussion (mild traumatic brain injury, MTBI)., Methods: This study evaluated post-MTBI neuropsychological testing of NFL players from 1996 to 2001. All athletes completed a standardized battery of neuropsychological tests and underwent postinjury neuropsychological testing within a few days after concussion. Test scores were compared with baselines using analysis of variance for athletes having on-field memory dysfunction, three or more concussions, or 7+ days out from practice and play., Results: The MTBI group did not display significant neuropsychological dysfunction relative to baseline scores within a few days of injury. However, a subsample of the injured athletes who displayed on-field memory dysfunction performed significantly more poorly on two of the memory tests. The neuropsychological test results of a group of athletes with a history of three or more MTBIs did not differ significantly compared with a group who had fewer than three concussions or compared with league-wide normative data. The neuropsychological performance of athletes who were out from full participation 7+ days was not significantly different from the group who returned to play within 7 days or the norms., Conclusion: Neuropsychological testing is used within the overall medical evaluation and care of NFL athletes. Players who experience MTBI generally demonstrate rapid recovery of neuropsychological performance, although poorer neuropsychological test results were related to on-field memory dysfunction. NFL players did not demonstrate evidence of neurocognitive decline after multiple (three or more) MTBIs or in those players out 7+ days. The data show that MTBI in this population is characterized by a rapid return of neuropsychological function in the days after injury.

Objective: A 6-year study was conducted to determine the signs, symptoms, and outcome of concussions with 7 or more (7+) days out from play or extended postconcussion recovery in the National Football League (NFL)., Methods: From 1996 to 2001, reporting of concussion was performed by NFL teams using a special standardized reporting form filled out by team physicians. Signs and symptoms were grouped by general symptoms, somatic complaints, cranial nerve effects, cognition problems, memory problems, and unconsciousness. Medical action taken and management were recorded. In all, 887 concussions were reported in practices and games., Results: There were 72 concussions (8.1%) involving 7+ days out from play. The highest frequency occurred in quarterbacks (14.8%), the return unit on special teams (11.8%), and secondary (10.8%). Quarterbacks had the highest odds ratio (OR) of 7+ days out with concussion (OR = 2.10, P = 0.049), whereas running backs had the lowest relative risk (OR = 0.13, P = 0.021). The greatest fraction of 7+ days out occurred in passing plays (36.1%) and kickoffs (22.2%). Many signs and symptoms occurred at a greater frequency on initial examination in players 7+ days out; the average number per player was 4.64 with 7+ days out versus 2.58 with fewer days out (t = 6.02, df = 77.1). The signs and symptoms with the highest incidence for 7+ days out were disorientation to time (chi(2) = 51.2, P = 001), retrograde amnesia (chi(2) = 33.2, P = 0.001), fatigue (chi(2) = 28.1, P = 0.001), and the general category of cognition problems (chi(2) = 21.7, P = 0.001). Loss of consciousness for more than 1 minute was a predictor of 7+ days out (chi(2) = 33.5, P = 0.001), although it occurred in only 7.9% of cases. Of players with 7+ days out, 72.2% were removed from the game and 12.5% were hospitalized. These frequencies were significantly greater than for players with fewer than 7 days out (chi(2) = 68.03, df = 3, P < 0.0001). Approximately 90% of players were managed by rest, irrespective of days out, but a greater fraction were given drug or medical therapies with prolonged days out., Conclusion: The most vulnerable players for 7+ days out with concussion were quarterbacks and the secondary in professional football. Although 8.1% of concussions involved 7+ days out, only 1.6% involved a prolonged postconcussion syndrome. They recovered from symptoms and had a consistent return to play in the NFL.

Objective: A 6-year study was conducted to determine the signs, symptoms, and management of repeat concussion in National Football League players., Methods: From 1996 to 2001, concussions were reported by 30 National Football League teams using a standardized reporting form filled out by team physicians with input from athletic trainers. Signs and symptoms were grouped by general symptoms, somatic complaints, cranial nerve effects, cognition problems, memory problems, and unconsciousness. Medical actions taken and management were recorded., Results: Data were captured for 887 concussions in practices and games involving 650 players. A total of 160 players experienced repeat injury, with 51 having three or more concussions during the study period. The median time between injuries was 374.5 days, with only six concussions occurring within 2 weeks of the initial injury. Repeat concussions were more prevalent in the secondary (16.9%), the kick unit on special teams (16.3%), and wide receivers (12.5%). The ball return carrier on special teams (odds ratio [OR] = 2.08, P = not significant) and quarterbacks (OR = 1.92, P < 0.1) had elevated odds for repeat injury, followed by the tight end (OR = 1.24, P = not significant) and linebackers (OR = 1.22, P = not significant). There were similar signs and symptoms with single and repeat concussion, except for a higher prevalence of somatic complaints in players on their repeat concussions compared with their first concussion (27.5% versus 18.8%, P < 0.05). More than 90% of players were managed by rest, and 57.5% of those with second injuries returned to play within a day. Players with three or more concussions had signs, symptoms, and treatment similar to those with only a single injury., Conclusion: The most vulnerable players for repeat concussion in professional football are the ball return carrier on special teams and quarterbacks. Single and repeat concussions are managed conservatively with rest, and most players return quickly to play.

Objective: A 6-year study was performed to determine the circumstances, causes, and outcomes of concussions in the National Football League., Methods: Between 1996 and 2001, the epidemiological features of concussions were recorded by National Football League teams with a standardized reporting form. Symptoms were reported and grouped as general symptoms, cranial nerve symptoms, memory or cognitive problems, somatic complaints, and loss of consciousness. The medical actions taken were recorded. In total, 787 game-related cases were reported, with information on the players involved, type of helmet impact, symptoms, medical actions, and days lost. Concussion risks were calculated according to player game positions., Results: There were 0.41 concussions per National Football League game. The relative risk was highest for quarterbacks (1.62 concussions/100 game-positions), followed by wide receivers (1.23 concussions/100 game-positions), tight ends (0.94 concussion/100 game-positions), and defensive secondaries (0.93 concussion/100 game-positions). The majority of concussions (67.7%) involved impact by another player's helmet. The remainder involved impact by other body regions of the striking player (20.9%) or ground contact (11.4%). The three most common symptoms of mild traumatic brain injury were headaches (55.0%), dizziness (41.8%), and blurred vision (16.3%). The most common signs noted in physical examinations were problems with immediate recall (25.5%), retrograde amnesia (18.0%), and information-processing problems (17.5%). In 58 of the reported cases (9.3%), the players lost consciousness; 19 players (2.4%) were hospitalized. A total of 92% of concussed players returned to practice in less than 7 days, but that value decreased to 69% with unconsciousness., Conclusion: The professional football players most vulnerable to concussions are quarterbacks, wide receivers, and defensive secondaries. Concussions involved 2.74 symptoms/injury, and players were generally removed from the game. More than one-half of the players returned to play within 1 day, and symptoms resolved in a short time in the vast majority of cases.

Objective: National Football League game video was analyzed for the typical locations of severe helmet impacts in professional football. By use of selected cases that were reconstructed in laboratory tests and reported previously, the magnitude and direction of force causing concussion was determined for these locations., Methods: Multiple video views were obtained for 182 severe helmet impacts that occurred between 1996 and 2001. From a top view, the helmet was divided into 45-degree quadrants with 0 degrees eyes forward. From a side view, it was divided into seven equal levels, four (+Q1 to +Q4) above the head center of gravity and three below (-Q1 to -Q3). The initial helmet contact was located in these regions. Thirty-one impacts were reconstructed with helmeted Hybrid III dummies involving 25 concussions. Measurement of head translational and rotational acceleration was used to determine the average and +/-1 standard deviation in responses, with impacts reflected to the right side., Results: From video, the majority (71%) of impact is to the helmet shell primarily from a striking player's helmet, arm, or shoulder pad to the side (45-135 degrees) or from ground contact to the back (135-180 degrees). Most impacts were high on the helmet at +Q2 to +Q4. The remainder (29%) were primarily from helmet contact on the facemask at an oblique frontal angle (0-45 degrees) and -Q3 to +Q1 height. From reconstructions, concussion occurred with the lowest peak head acceleration in facemask impacts at 78 +/- 18 g versus an average 107 to 117 g for impacts on other quadrants (t = 2.90, P < 0.005). There was a significantly higher head acceleration for concussed versus nonconcussed players (t = 2.85, P < 0.05). The vector of peak force was essentially horizontal for facemask impacts and downward at 12 to 27 degrees for impacts to the helmet side and back. Concussion in professional football involves four typical conditions, as follows: A, 0- to 45-degree quadrant, -Q3 to +Q3 level, peak force 49 +/- 18 degrees from front and horizontal; B, 45- to 90-degree quadrant, -Q2 to +Q3 level, peak force 73 +/- 12 degrees and horizontal; C, 90- to 135-degree quadrant, +Q1 to +Q4 level, peak force 97 +/- 9 degrees and 12 degrees downward; and D, 135- to 180-degree quadrant, +Q1 to +Q4 level, peak force 157 +/- 1 degrees and 27 degrees downward. Concussed players averaged 3.6 +/- 2.7 initial signs and symptoms. The most common were headaches, dizziness, immediate recall problems, and difficulty with information processing., Conclusion: The location, direction, and severity of helmet impacts causing concussion in the National Football League have been defined from analysis of game video and laboratory reconstruction. These conditions define the circumstances in which helmets need to reduce head injury risks in professional football.

Objective: Concussion in professional football was studied with respect to impact types and injury biomechanics. A combination of video surveillance and laboratory reconstruction of game impacts was used to evaluate concussion biomechanics., Methods: Between 1996 and 2001, videotapes of concussions and significant head impacts were collected from National Football League games. There were clear views of the direction and location of the helmet impact for 182 cases. In 31 cases, the speed of impact could be determined with analysis of multiple videos. Those cases were reconstructed in laboratory tests using helmeted Hybrid III dummies and the same impact velocity, direction, and head kinematics as in the game. Translational and rotational accelerations were measured, to define concussion biomechanics. Several studies were performed to ensure the accuracy and reproducibility of the video analysis and laboratory methods used., Results: Concussed players experienced head impacts of 9.3 +/- 1.9 m/s (20.8 +/- 4.2 miles/h). There was a rapid change in head velocity of 7.2 +/- 1.8 m/s (16.1 +/- 4.0 miles/h), which was significantly greater than that for uninjured struck players (5.0 +/- 1.1 m/s, 11.2 +/- 2.5 miles/h; t = 2.9, P < 0.005) or striking players (4.0 +/- 1.2 m/s, 8.9 +/- 2.7 miles/h; t = 7.6, P < 0.001). The peak head acceleration in concussion was 98 +/- 28 g with a 15-millisecond half-sine duration, which was statistically greater than the 60 +/- 24 g for uninjured struck players (t = 3.1, P < 0.005). Concussion was primarily related to translational acceleration resulting from impacts on the facemask or side, or falls on the back of the helmet. Concussion could be assessed with the severity index or head injury criterion (the conventional measures of head injury risk). Nominal tolerance levels for concussion were a severity index of 300 and a head injury criterion of 250., Conclusion: Concussion occurs with considerable head impact velocity and velocity changes in professional football. Current National Operating Committee on Standards for Athletic Equipment standards primarily address impacts to the periphery and crown of the helmet, whereas players are experiencing injuries in impacts to the facemask, side, and back of the helmet. New tests are needed to assess the performance of helmets in reducing concussion risks involving high-velocity and long-duration injury biomechanics.