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.

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.

Head Impact Modeling to Support a Rotational Combat Helmet Drop Test

2021 ◽  
Author(s):  
Ryan Terpsma ◽  
Rika Wright Carlsen ◽  
Ron Szalkowski ◽  
Sushant Malave ◽  
Alice Lux Fawzi ◽  
...  
Keyword(s):  
Human Head ◽  
Mechanical Stimulus ◽  
Scientific Basis ◽  
Test Method ◽  
Drop Test ◽  
Head Impacts ◽  
Digital Twin ◽  
Brain Deformation ◽  
Acceleration Time Histories ◽  
Hybrid Iii

ABSTRACT Introduction The Advanced Combat Helmet (ACH) military specification (mil-spec) provides blunt impact acceleration criteria that must be met before use by the U.S. warfighter. The specification, which requires a helmeted magnesium Department of Transportation (DOT) headform to be dropped onto a steel hemispherical target, results in a translational headform impact response. Relative to translations, rotations of the head generate higher brain tissue strains. Excessive strain has been implicated as a mechanical stimulus leading to traumatic brain injury (TBI). We hypothesized that the linear constrained drop test method of the ACH specification underreports the potential for TBI. Materials and Methods To establish a baseline of translational acceleration time histories, we conducted linear constrained drop tests based on the ACH specification and then performed simulations of the same to verify agreement between experiment and simulation. We then produced a high-fidelity human head digital twin and verified that biological tissue responses matched experimental results. Next, we altered the ACH experimental configuration to use a helmeted Hybrid III headform, a freefall cradle, and an inclined anvil target. This new, modified configuration allowed both a translational and a rotational headform response. We applied this experimental rotation response to the skull of our human digital twin and compared brain deformation relative to the translational baseline. Results The modified configuration produced brain strains that were 4.3 times the brain strains from the linear constrained configuration. Conclusions We provide a scientific basis to motivate revision of the ACH mil-spec to include a rotational component, which would enhance the test’s relevance to TBI arising from severe head impacts.

scholarly journals Analysis of HIC and Hydrostatic Pressure in the Human Head during NOCSAE Tests of American Football Helmets

2021 ◽  
Vol 11 (3) ◽  
pp. 287
Author(s):  
Mateusz Dymek ◽  
Mariusz Ptak ◽  
Monika Ratajczak ◽  
Fábio A. O. Fernandes ◽  
Artur Kwiatkowski ◽  
...  
Keyword(s):  
Human Head ◽  
Numerical Approach ◽  
American Football ◽  
Head Model ◽  
Head Impacts ◽  
Social Burden ◽  
Direct Head ◽  
Hybrid Iii ◽  
Football Helmets ◽  
Head Injury Criteria

Brain damage is a serious economic and social burden. Contact sports such as American football, are one of the most common sources of concussions. The biomechanical response of the head–helmet system caused by dynamic loading plays a major role. The literature has focused on measuring the resultant kinematics that act on the head and helmet during tackles. However, few studies have focused on helmet validation tests, supported by recent findings and emerging numerical approaches. The future of helmet standards could benefit from insights at the level of injury mechanisms, using numerical tools to assess the helmets. Therefore, in this work, a numerical approach is employed to investigate the influence of intracranial pressure (ICP) on brain pathophysiology during and after helmeted impacts, which are common in American football. The helmeted impacts were performed at several impact locations according to the NOCSAE standard (configurations A, AP, B, C, D, F, R, UT). In order to evaluate the ICP levels, the αHEAD finite element head and brain model was combined with a Hybrid III-neck structure and then coupled with an American football helmet to simulate the NOCSAE impacts. In addition, the ICP level was analyzed together with the resulting HIC value, since the latter is commonly used, in this application and others, as the injury criterion. The obtained results indicate that ICP values exceed the common threshold of head injury criteria and do not correlate with HIC values. Thus, this work raises concern about applying the HIC to predict brain injury in American football direct head impacts, since it does not correlate with ICP predicted with the FE head model.

scholarly journals Tau isoforms are differentially expressed across the hippocampus in chronic traumatic encephalopathy and Alzheimer’s disease

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Jonathan D. Cherry ◽  
Camille D. Esnault ◽  
Zachary H. Baucom ◽  
Yorghos Tripodis ◽  
Bertrand R. Huber ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Chronic Traumatic Encephalopathy ◽  
Temporal Cortex ◽  
Head Impacts ◽  
Hippocampal Subfields ◽  
Mild Disease ◽  
Tau Isoforms ◽  
Ghost Tangles

AbstractChronic traumatic encephalopathy (CTE) is a progressive neurodegenerative disease, characterized by hyperphosphorylated tau, found in individuals with a history of exposure to repetitive head impacts. While the neuropathologic hallmark of CTE is found in the cortex, hippocampal tau has proven to be an important neuropathologic feature to examine the extent of disease severity. However, the hippocampus is also heavily affected in many other tauopathies, such as Alzheimer’s disease (AD). How CTE and AD differentially affect the hippocampus is unclear. Using immunofluorescent analysis, a detailed histologic characterization of 3R and 4R tau isoforms and their differential accumulation in the temporal cortex in CTE and AD was performed. CTE and AD were both observed to contain mixed 3R and 4R tau isoforms, with 4R predominating in mild disease and 3R increasing proportionally as pathological severity increased. CTE demonstrated high levels of tau in hippocampal subfields CA2 and CA3 compared to CA1. There were also low levels of tau in the subiculum compared to CA1 in CTE. In contrast, AD had higher levels of tau in CA1 and subiculum compared to CA2/3. Direct comparison of the tau burden between AD and CTE demonstrated that CTE had higher tau densities in CA4 and CA2/3, while AD had elevated tau in the subiculum. Amyloid beta pathology did not contribute to tau isoform levels. Finally, it was demonstrated that higher levels of 3R tau correlated to more severe extracellular tau (ghost tangles) pathology. These findings suggest that mixed 3R/4R tauopathies begin as 4R predominant then transition to 3R predominant as pathological severity increases and ghost tangles develop. Overall, this work demonstrates that the relative deposition of tau isoforms among hippocampal subfields can aid in differential diagnosis of AD and CTE, and might help improve specificity of biomarkers for in vivo diagnosis.

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 Innovative Test Rig for Jet Fuels Thermal Stability Testing / Innowacyjne Stanowisko Badawcze Do Określania Stabilności Termicznej Paliw Lotniczych

2014 ◽  
Vol 29 (1) ◽  
pp. 15-22
Author(s):  
Jarosław Sarnecki
Keyword(s):  
Thermal Stability ◽  
Laboratory Test ◽  
Thermal Conditions ◽  
Standard Test ◽  
Test Method ◽  
Jet Fuels ◽  
Stability Testing ◽  
Test Rig ◽  
Standard Test Method ◽  
Laboratory Test Method

Abstract The article deals with laboratory test method for jet fuels thermal stability testing. Author described the reasons that led to test rig preparation, its construction and operation principles. Innovative test rig for jet fuels thermal stability testing enables research in wide thermal conditions and different pressures. Testing capabilities and advantages compared with currently used standard test method of jet fuels thermal stability testing according to ASTM D3241 have been also presented

scholarly journals Video Analysis and Verification of Direct Head Impacts Recorded by Wearable Sensors in Junior Rugby League Players

2020 ◽  
Author(s):  
Lauchlan John Carey ◽  
Douglas P Terry ◽  
Andrew McIntosh ◽  
Peter Stanwell ◽  
Grant L Iverson ◽  
...  
Keyword(s):  
Video Analysis ◽  
Wearable Sensors ◽  
Case Series ◽  
Rugby League ◽  
Secondary Source ◽  
Head Impacts ◽  
Youth Athletes ◽  
Video Review ◽  
Direct Head ◽  
Elite Level

Abstract Background: Rugby League is a high-intensity collision sport that carries a risk of concussion. Youth athletes are considered to be more vulnerable and take longer to recover from concussion than adult athletes. Purpose: To review head impact events in elite level junior representative rugby league and to verify and analyze x-patchTM recorded impacts via video analysis.Study Design: Observational case series.Methods: The x-patchTM was used on twenty-one adolescent players (thirteen forwards and eight backs) during a 2017 junior representative rugby league competition. Game day footage, recorded by a trained videographer from a single camera, was synchronized with accelerometer timestamps. Impacts were double verified by video review. Impact rates, playing characteristics, and game play situations were described.Results: The x-patchTM recorded 624 impacts 20g between game start and finish, of which 564 (90.4%) were verified on video. Upon video review, 413 (73.2%) of all verified impacts 20g where determined to be direct head impacts. Direct head impacts 20g occurred at a rate of 5.2 impacts per game hour; 7.6 for forwards and 3.0 for backs (range=0-18.2). A defender’s arm directly impacting the head of the ball carrier was the most common event, accounting for 21.3% (n=120) of all impacts, and 46.7% of all “hit-up” impacts. There were no medically diagnosed concussions during the competition.Conclusion: The majority (90.4%) of impacts 20g recorded by the x-patchTM sensor were verified by video. Double verification of direct head impacts in addition to cross-verification of sensor recorded impacts using a secondary source such as synchronized video review can be used to ensure accuracy and validation of data.

scholarly journals Skrining Mekanisme Kerja Daun Malaka (Phyllanthus emblica L.) Sebagai Antidiabetes

2018 ◽  
Vol 1 (3) ◽  
pp. 106-110
Author(s):  
Novi Irwan Fauzi ◽  
Seno Aulia Ardiansyah ◽  
Saeful Hidayat
Keyword(s):  
Mechanism Of Action ◽  
Inhibitory Activity ◽  
Leaf Extract ◽  
Test Method ◽  
Diabetic Rat ◽  
Phyllanthus Emblica ◽  
Insulin Sensitizer ◽  
Water Fraction

Daun malaka (Phyllanthus emblica L.) mempunyai potensi digunakan sebagai alternatif obat antidiabetes. Daun malaka menunjukkan efek hipoglikemia pada tikus yang diinduksi aloksan. Namun, mekanisme kerjanya belum diketahui pasti. Penelitian ini dilakukan dalam rangka skrining mekanisme kerja daun malaka sebagai antidiabetes. Skrining mekanisme kerja dilakukan terhadap fraksi air daun malaka melalui uji aktivitas inhibisi enzim α-glukosidase serta α-amilase secara in vitro dan pengujian aktivitas insulin-sensitizer terhadap ekstrak daun malaka dengan metode tes toleransi insulin secara in vivo. Fraksi air daun malaka menunjukkan aktivitas inhibisi terhadap enzim α-glukosidase serta α-amilase dengan nilai IC50 (Inhibitor Concentration 50) pada kedua enzim tersebut berturut-turut adalah 0,87% dan 8,64% b/v. Pada uji aktivitas insulin sensitizer, pemberian ekstrak daun malaka dapat meningkatkan sensitivitas insulin pada tikus diabet dengan kondisi resistensi insulin. Nilai KTTI pada kelompok tikus diabet yang diberi ekstrak daun malaka dosis 100 dan 500 mg/kgbb tikus (74,89 dan 75,57) lebih tinggi dibandingkan kelompok tikus diabet (38,41) dan kadar glukosa darah yang lebih rendah selama interval waktu pengukuran. Daun malaka telah diketahui mampu meningkatkan sekresi insulin dan pada penelitian ini menunjukkan aktivitas inhibisi enzim α-glukosidase serta α-amilase secara in vitro dan menunjukkan aktivitas insulinsensitizer pada tikus diabet dengan kondisi resistensi insulin.   Malaka leaf (Phyllanthus emblica L.) has the potential to be used as an alternative antidiabetic drug. Malacca leaves showed hypoglycemia effect in rat induced by alloxan. However, the mechanism of action is not yet known. This study was conducted to evaluate the mechanism of action of Malaka leaves as antidiabetic. Screening of the mechanism of action was carried out on the water fraction of Malaka leaf  byinhibitory activity examination  on α-glucosidase and α-amylase by in vitro studyand Evaluation of insulin-sensitizer activity of Maaka leaf leaf extract was conducted by invivo  insulin tolerance test method. Malaka leaf water fraction showed inhibitory activity against the α-glucosidase and α-amylase with IC50 values ​​(Inhibitory Concentration 50)  of0.87% and 8.64% b / v on both enzyme, respectively. The evaluation of insulin sensitizer revelead that administration ofMalaka  leaf extract can increase insulin sensitivity in diabetic rat with insulin resistance.KTTI values ​​in diabetic rats given malaka extract  at the dose of 100 and 500 mg / kg BW (74.89 and 75.57) were higher than diabetics rat (38.41) and the extract also decrease blood glucose levels during measurement time intervals . Malaka leafhas been known to increase insulin secretion and the study showedthe  inhibitory activity on α-glucosidase and α-amylase by in vitro study and showed insulinsensitizer activity in diabetic rat with insulin resistance.

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