On-Field Performance of an Instrumented Mouthguard for Detecting Head Impacts in American Football

2020 ◽  
Vol 48 (11) ◽  
pp. 2599-2612
Author(s):  
Lee F. Gabler ◽  
Samuel H. Huddleston ◽  
Nathan Z. Dau ◽  
David J. Lessley ◽  
Kristy B. Arbogast ◽  
...  
Keyword(s):  
Field Performance ◽  
American Football ◽  
Head Impacts

scholarly journals Fluctuations in blood biomarkers of head trauma in NCAA football athletes over the course of a season

2019 ◽  
Vol 130 (5) ◽  
pp. 1655-1662 ◽  
Author(s):  
Jonathan M. Oliver ◽  
Anthony J. Anzalone ◽  
Jason D. Stone ◽  
Stephanie M. Turner ◽  
Damond Blueitt ◽  
...  
Keyword(s):  
Head Trauma ◽  
Plasma Concentrations ◽  
Objective Measure ◽  
American Football ◽  
Neurological Injury ◽  
Cumulative Exposure ◽  
Serum Concentrations ◽  
Blood Biomarkers ◽  
Head Impacts ◽  
Subconcussive Head Trauma

OBJECTIVERepetitive subconcussive head trauma is a consequence of participation in contact sports and may be linked to neurodegenerative diseases. The degree of neurological injury caused by subconcussive head trauma is not easily detectible, and this injury does not induce readily identifiable clinical signs or symptoms. Recent advancements in immunoassays make possible the detection and quantification of blood biomarkers linked to head trauma. Identification of a blood biomarker that can identify the extent of neurological injury associated with subconcussive head trauma may provide an objective measure for informed decisions concerning cumulative exposure to subconcussive head trauma. The purpose of the current study was to examine changes in the blood biomarkers of subconcussive head trauma over the course of an American football season.METHODSThirty-five National Collegiate Athletic Association (NCAA) American football athletes underwent blood sampling throughout the course of a football season. Serial samples were obtained throughout the 2016 season, during which the number and magnitude of head impacts changed. Blood samples were analyzed for plasma concentrations of tau and serum concentrations of neurofilament light polypeptide (NF-L). Athletes were grouped based on their starter status, because athletes identified as starters are known to sustain a greater number of impacts. Between-group differences and time-course differences were assessed.RESULTSIn nonstarters, plasma concentrations of tau decreased over the course of the season, with lower values observed in starters; this resulted in a lower area under the curve (AUC) (starters: 416.78 ± 129.17 pg/ml/day; nonstarters: 520.84 ± 163.19 pg/ml/day; p = 0.050). Plasma concentrations of tau could not be used to discern between starters and nonstarters. In contrast, serum concentrations of NF-L increased throughout the season as head impacts accumulated, specifically in those athletes categorized as starters. The higher serum concentrations of NF-L observed in starters resulted in a larger AUC (starters: 1605.03 ± 655.09 pg/ml/day; nonstarters: 1067.29 ± 272.33 pg/ml/day; p = 0.007). The AUC of the receiver operating characteristic curve analyses displayed fair to modest accuracy to identify athletes who were starters with the use of serum NF-L following periods of repetitive impacts.CONCLUSIONSThe different patterns observed in serum NF-L and plasma tau concentrations provide preliminary evidence for the use of blood biomarkers to detect the neurological injury associated with repetitive subconcussive head trauma. Although further investigation is necessary, such findings might lay the foundation for the further development of an objective measure for the detection of neurological injury caused by subconcussive head trauma.

Association Between Antemortem FLAIR White Matter Hyperintensities and Neuropathology in Brain Donors Exposed to Repetitive Head Impacts

Neurology ◽  
2021 ◽  
pp. 10.1212/WNL.0000000000013012
Author(s):  
Madeline Uretsky ◽  
Sylvain Bouix ◽  
Ronald J. Killiany ◽  
Yorghos Tripodis ◽  
Brett Martin ◽  
...  
Keyword(s):  
White Matter ◽  
White Matter Hyperintensities ◽  
Microvascular Disease ◽  
Head Impact ◽  
American Football ◽  
Football Players ◽  
Head Impacts ◽  
Repetitive Head Impacts ◽  
Pathological Correlation ◽  
Daily Function

Background and Objectives:Late neuropathologies of repetitive head impacts from contact sports can include chronic traumatic encephalopathy (CTE) and white matter degeneration. White matter hyperintensities (WMH) on fluid attenuated inversion recovery (FLAIR) MRI scans are often viewed as microvascular disease from vascular risk, but might have unique underlying pathologies and risk factors in the setting of repetitive head impacts. We investigated the neuropathological correlates of antemortem WMH in brain donors exposed to repetitive head impacts. The association between WMH, and repetitive head impact exposure and informant-reported cognitive and daily function were tested.Methods:This imaging-pathological correlation study included symptomatic deceased men exposed to repetitive head impacts. Donors had antemortem FLAIR scans from medical records and were without evidence of CNS neoplasm, large vessel infarcts, hemorrhage, and/or encephalomalacia. WMH were quantified using log-transformed values for total lesion volume (TLV), calculated using the lesion prediction algorithm from the Lesion Segmentation Toolbox. Neuropathological assessments included semi-quantitative ratings of white matter rarefaction, cerebrovascular disease, p-tau severity (CTE stage, dorsolateral frontal cortex), and Aβ. Among football players, years of play was a proxy for repetitive head impact exposure. Retrospective informant-reported cognitive and daily function were assessed using the Cognitive Difficulties Scale (CDS) and Functional Activities Questionnaire (FAQ). Regression models controlled for demographics, diabetes, hypertension, and MRI resolution. Statistical significance was defined as p<0.05.Results:The sample included 75 donors: 67 football players and 8 non-football contact sport athletes and/or military veterans. Dementia was the most common MRI indication (64%). Fifty-three (70.7%) had CTE at autopsy. Log-TLV was associated with white matter rarefaction (OR=2.32, 95% CI=1.03,5.24, p=0.04), arteriolosclerosis (OR=2.38, 95% CI=1.02,5.52, p=0.04), CTE stage (OR=2.58, 95% CI=1.17,5.71, p=0.02), and dorsolateral frontal p-tau severity (OR=3.03, 95% CI=1.32,6.97, p=0.01). There was no association with Aβ. More years of football play was associated with log-TLV (b=0.04, 95% CI=0.01,0.06, p=0.01). Greater log-TLV correlated with higher FAQ (unstandardized beta=4.94, 95% CI=0.42,8.57, p=0.03) and CDS scores (unstandardized beta=15.35, 95% CI=-0.27,30.97, p=0.05).Discussion:WMH might capture long-term white matter pathologies from repetitive head impacts, including those from white matter rarefaction and p-tau, in addition to microvascular disease. Prospective imaging-pathological correlation studies are needed.Classification of Evidence:This study provides Class IV evidence of associations between FLAIR white matter hyperintensities, and neuropathological changes (white matter rarefaction, arteriolosclerosis, p-tau accumulation), years of American football play, and reported cognitive symptoms in symptomatic brain donors exposed to repetitive head impacts.

The Influence of Neck Stiffness on Head Kinematics and Maximum Principal Strain Associated With Youth American Football Collisions

2021 ◽  
pp. 1-8
Author(s):  
Janie Cournoyer ◽  
David Koncan ◽  
Michael D. Gilchrist ◽  
T. Blaine Hoshizaki
Keyword(s):  
American Football ◽  
Principal Strain ◽  
Neck Stiffness ◽  
Head Impacts ◽  
Head Kinematics ◽  
Upper Trapezius ◽  
Maximum Principal Strain ◽  
Direct Head ◽  
Hybrid Iii ◽  
Neck Strength

Understanding the relationship between head mass and neck stiffness during direct head impacts is especially concerning in youth sports where athletes have higher proportional head mass to neck strength. This study compared 2 neck stiffness conditions for peak linear and rotational acceleration and brain tissue deformations across 3 impact velocities, 3 impact locations, and 2 striking masses. A pendulum fitted with a nylon cap was used to impact a fifth percentile hybrid III headform equipped with 9 accelerometers and fitted with a youth American football helmet. The 2 neck stiffness conditions consisted of a neckform with and without resistance in 3 planes, representing the upper trapezius, the splenius capitis, and the sternocleidomastoid muscles. Increased neck stiffness resulted in significant changes in head kinematics and maximum principal strain specific to impact velocity, impact location, and striking mass.

scholarly journals Accident reconstructions of falls, collisions, and punches in sports

2020 ◽  
Vol 4 ◽  
pp. 205970022093695
Author(s):  
Marshall Kendall ◽  
Anna Oeur ◽  
Susan E Brien ◽  
Michael Cusimano ◽  
Shawn Marshall ◽  
...  
Keyword(s):  
Finite Element ◽  
Brain Tissue ◽  
Ice Hockey ◽  
American Football ◽  
External Loading ◽  
Loading Conditions ◽  
Head Impacts ◽  
Impact Parameters ◽  
Impact Events ◽  
Impact Mass

Objective Impacts to the head are the primary cause of concussive injuries in sport and can occur in a multitude of different environments. Each event is composed of combinations of impact characteristics (striking velocity, impact mass, and surface compliance) that present unique loading conditions on the head and brain. The purpose of this study was to compare falls, collisions, and punches from accident reconstructions of sports-related head impacts using linear, rotational accelerations and maximal principal strain of brain tissue from finite element simulation. Methods This study compared four types of head impact events through reconstruction. Seventy-two head impacts were taken from medical reports of accidental falls and game video of ice hockey, American football, and mixed-martial arts. These were reconstructed using physical impact systems to represent helmeted and unhelmeted falls, player-to-player collisions, and punches to the head. Head accelerations were collected using a Hybrid III headform and were input into a finite element brain model used to approximate strain in the cerebrum associated with the external loading conditions. Results Significant differences ( p < 0.01) were found for peak linear and rotational accelerations magnitudes (30–300 g and 3.2–7.8 krad/s2) and pulse durations between all impact event types characterized by unique impact parameters. The only exception was found where punch impacts and helmeted falls had similar rotational durations. Regression analysis demonstrated that increases to strain from unhelmeted falls were significantly influenced by both linear and rotational accelerations, meanwhile helmeted falls, punches, and collisions were influenced by rotational accelerations alone. Conclusion This report illustrates that the four distinct impact events created unique peak head kinematics and brain tissue strain values. These distinct patterns of head acceleration characteristics suggest that it is important to keep in mind that head injury can occur from a range of low to high acceleration magnitudes and that impact parameters (surface compliance, striking velocity, and impact mass) play an important role on the duration-dependent tolerance to impact loading.

Association between Muscle Damage and Head Impacts in High School American Football

2019 ◽  
Vol 41 (01) ◽  
pp. 36-43 ◽  
Author(s):  
Megan E. Huibregtse ◽  
Steven W. Zonner ◽  
Keisuke Ejima ◽  
Zachary W. Bevilacqua ◽  
Sharlene D. Newman ◽  
...  
Keyword(s):  
High School ◽  
Skeletal Muscle ◽  
Muscle Damage ◽  
Physical Exertion ◽  
American Football ◽  
Health Concern ◽  
Physiological Factors ◽  
Prospective Longitudinal Study ◽  
Head Impacts ◽  
Prospective Longitudinal

AbstractSubconcussive head impacts (SHI), defined as impacts to the cranium that do not result in concussion symptoms, are gaining traction as a major public health concern. The contribution of physiological factors such as physical exertion and muscle damage to SHI-dependent changes in neurological measures remains unknown. A prospective longitudinal study examined the association between physiological factors and SHI kinematics in 15 high school American football players over one season. Players wore a sensor-installed mouthguard for all practices and games, recording frequency and magnitude of all head impacts. Serum samples were collected at 12 time points (pre-season, pre- and post-game for five in-season games, and post-season) and were assessed for an isoenzyme of creatine kinase (CK-MM) primarily found in skeletal muscle. Physical exertion was estimated in the form of excess post-exercise oxygen consumption (EPOC) from heart rate data captured during the five games. Mixed-effect regression models indicated that head impact kinematics were significantly and positively associated with change in CK-MM but not EPOC. There was a significant and positive association between CK-MM and EPOC. These data suggest that when examining SHI, effects of skeletal muscle damage should be considered when using outcome measures that may have an interaction with muscle damage.

scholarly journals Similar head impact acceleration measured using instrumented ear patches in a junior rugby union team during matches in comparison with other sports

2016 ◽  
Vol 18 (1) ◽  
pp. 65-72 ◽  
Author(s):  
Doug A. King ◽  
Patria A. Hume ◽  
Conor Gissane ◽  
Trevor N. Clark
Keyword(s):  
Injury Risk ◽  
Linear Acceleration ◽  
Rugby Union ◽  
Head Impact ◽  
American Football ◽  
Football Players ◽  
Head Impacts ◽  
Impact Acceleration ◽  
The Impact ◽  
Rugby Players

OBJECTIVE Direct impact with the head and the inertial loading of the head have been postulated as major mechanisms of head-related injuries, such as concussion. METHODS This descriptive observational study was conducted to quantify the head impact acceleration characteristics in under-9-year-old junior rugby union players in New Zealand. The impact magnitude, frequency, and location were collected with a wireless head impact sensor that was worn by 14 junior rugby players who participated in 4 matches. RESULTS A total of 721 impacts > 10g were recorded. The median (interquartile range [IQR]) number of impacts per player was 46 (IQR 37–58), resulting in 10 (IQR 4–18) impacts to the head per player per match. The median impact magnitudes recorded were 15g (IQR 12g–21g) for linear acceleration and 2296 rad/sec2 (IQR 1352–4152 rad/sec2) for rotational acceleration. CONCLUSIONS There were 121 impacts (16.8%) above the rotational injury risk limit and 1 (0.1%) impact above the linear injury risk limit. The acceleration magnitude and number of head impacts in junior rugby union players were higher than those previously reported in similar age-group sports participants. The median linear acceleration for the under-9-year-old rugby players were similar to 7- to 8-year-old American football players, but lower than 9- to 12-year-old youth American football players. The median rotational accelerations measured were higher than the median and 95th percentiles in youth, high school, and collegiate American football players.

An Investigation of the NOCSAE Linear Impactor Test Method Based on In Vivo Measures of Head Impact Acceleration in American Football

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Joseph T. Gwin ◽  
Jeffery J. Chu ◽  
Solomon G. Diamond ◽  
P. David Halstead ◽  
Joseph J. Crisco ◽  
...  
Keyword(s):  
Laboratory Test ◽  
Impulse Response ◽  
Test Method ◽  
Drop Test ◽  
Process Models ◽  
American Football ◽  
Head Impacts ◽  
Response Characteristics ◽  
Direct Head

The performance characteristics of football helmets are currently evaluated by simulating head impacts in the laboratory using a linear drop test method. To encourage development of helmets designed to protect against concussion, the National Operating Committee for Standards in Athletic Equipment recently proposed a new headgear testing methodology with the goal of more closely simulating in vivo head impacts. This proposed test methodology involves an impactor striking a helmeted headform, which is attached to a nonrigid neck. The purpose of the present study was to compare headform accelerations recorded according to the current (n=30) and proposed (n=54) laboratory test methodologies to head accelerations recorded in the field during play. In-helmet systems of six single-axis accelerometers were worn by the Dartmouth College men’s football team during the 2005 and 2006 seasons (n=20,733 impacts; 40 players). The impulse response characteristics of a subset of laboratory test impacts (n=27) were compared with the impulse response characteristics of a matched sample of in vivo head accelerations (n=24). Second- and third-order underdamped, conventional, continuous-time process models were developed for each impact. These models were used to characterize the linear head/headform accelerations for each impact based on frequency domain parameters. Headform linear accelerations generated according to the proposed test method were less similar to in vivo head accelerations than headform accelerations generated by the current linear drop test method. The nonrigid neck currently utilized was not developed to simulate sport-related direct head impacts and appears to be a source of the discrepancy between frequency characteristics of in vivo and laboratory head/headform accelerations. In vivo impacts occurred 37% more frequently on helmet regions, which are tested in the proposed standard than on helmet regions tested currently. This increase was largely due to the addition of the facemask test location. For the proposed standard, impactor velocities as high as 10.5 m/s were needed to simulate the highest energy impacts recorded in vivo. The knowledge gained from this study may provide the basis for improving sports headgear test apparatuses with regard to mimicking in vivo linear head accelerations. Specifically, increasing the stiffness of the neck is recommended. In addition, this study may provide a basis for selecting appropriate test impact energies for the standard performance specification to accompany the proposed standard linear impactor test method.

scholarly journals High Energy American Football Head Impacts to the Side and Rear Damaging Than to the Front

Neurology ◽  
2019 ◽  
Vol 93 (14 Supplement 1) ◽  
pp. S10.1-S10
Author(s):  
Adam Bartsch ◽  
Edward Benzel ◽  
Sergey Samorezov ◽  
Vincent Miele
Keyword(s):  
High Energy ◽  
Head Impact ◽  
American Football ◽  
Dose Response Relationship ◽  
Positive Events ◽  
Head Impacts ◽  
Injury Threshold ◽  
Impact Location ◽  
Player Game ◽  
Concussive Injury

ObjectiveThe aim of this study was to investigate head impact doses in American football. We analyzed time-synchronized video and data collected during n = 445 player-games of American football resulting in 2851video-verified impacts. Cases where a player sustained impacts and on video was demonstrably witnessed to meet the NFL’s “No-go” criteria were analyzed in-depth.BackgroundIn 2011, after reviewing scalar on-field kinematics data leading concussion clinicians concluded “Recent studies suggest that a concussive injury threshold is elusive, and may, in fact, be irrelevant when predicting the clinical outcome”.1 It is likely that higher fidelity estimates of spatial and temporal impact parameters will clarify the currently unclear impact dose-response relationship.Design/MethodsA total of 2851 video-verified head impacts were identified from 445 player-games. Each event was time-synchronized to video. Any events collected when the athlete was not being impacted in the head were discarded. The remaining true positive events were scrutinized based on published methods to confirm a head impact occurred in the video and the computed motion was physically realistic and matched the video.ResultsWe found a median of 5 video-verified head impacts per player-game, which is far fewer than published studies without video verification.11 For the four players with “No-go” impacts, all were to the side/rear. Coronal plane impact sensitivity has been a hypothesized clinical injury mechanism12 and our results support that hypothesis.ConclusionsWe did not see high PLA/PAA impacts without obvious player “No-go” observations. This finding disagrees with other studies that have reported high PLA/PAA impacts without any demonstrable “No-go” observations13. High energy impacts to the side and rear of the head are more damaging than similar magnitude impacts to the forehead. Armed with this knowledge, clinicians should have more fidelity in their understanding of real-time impact location and severity, and how it relates to athlete concussion risk.

scholarly journals Impact on the head during collisions between university American football players - focusing on the number of head impacts and linear head acceleration -

2017 ◽  
Vol 6 (4) ◽  
pp. 241-249 ◽  
Author(s):  
Takashi Fukuda ◽  
Sekiya Koike ◽  
Syumpei Miyakawa ◽  
Hiroto Fujiya ◽  
Yuki Yamamoto
Keyword(s):  
American Football ◽  
Football Players ◽  
Head Acceleration ◽  
Head Impacts

scholarly journals Association of physiological variables with football subconcussive head impacts: Why measure?

2018 ◽  
Author(s):  
Megan E. Huibregtse ◽  
Steven W. Zonner ◽  
Keisuke Ejima ◽  
Zachary W. Bevilacqua ◽  
Sharlene Newman ◽  
...  
Keyword(s):  
High School ◽  
Skeletal Muscle ◽  
Heart Rate ◽  
Muscle Damage ◽  
Physical Exertion ◽  
Head Impact ◽  
American Football ◽  
Physiological Factors ◽  
Head Impacts ◽  
Skeletal Muscle Damage

AbstractSubconcussive head impacts, defined as impacts to the cranium that do not result in clinical symptoms of concussion, are gaining traction as a major public health concern. Researchers begin to suggest subconcussive impact-dependent changes in various neurological measures. However, a contribution of physiological factors such as physical exertion and muscle damage has never been accounted. We conducted a prospective longitudinal study during a high school American football season to examine the association between physiological factors and subconcussive head impact kinematics. Fifteen high-school American football players volunteered in the study. A sensor-installed mouthguard recorded the number of head impacts, peak linear (PLA: g) and peak rotational (PRA: rad/s2) head accelerations from every practice and game. Serum samples were collected at 12 time points (pre-season baseline, five in-season pre-post games, and post-season) and assessed for the creatine kinase skeletal muscle-specific isoenzyme (CK-MM), as a surrogate for skeletal muscle damage. Physical exertion was estimated in the form of excess post-exercise oxygen consumption (EPOC) from heart rate data captured during five games via a wireless heart rate monitor. A total of 9,700 hits, 214,492 g, and 19,885,037 rad/s2 were recorded from 15 players across the study period. Mixed-effect regression models indicated that head impact kinematics (frequency, PLA, and PRA) were significantly and positively associated with CK-MM increase, but not with EPOC. There was a significant and positive association between CK-MM and EPOC. These data suggest that skeletal muscle damage effects should be considered when using outcome measures that may have an interaction with muscle damage, including inflammatory biomarkers and vestibular/balance tests.

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