The authors would like to acknowledge Ms. Angela Wirsching, who was a key contributor to the research we cite in the representative results section.

The authors verify that the Indiana University Institutional Review Board approved the study (protocol # 1610743422) and written informed consent was obtained.
NOTE: The SSHM was integrated into a repeated measures design that is intended to investigate changes among dependent variables within subjects at 0 h, 2 h, and 24 h post-intervention compared to individual pre-intervention values. This study design allows researchers to track changes for a 24 h period, which is the typical timeframe between athletic practices. In the present study, soccer players were randomly assigned to either a soccer heading (n = 18) or a soccer kicking group (n = 16).
1. Setup
<ol>
	<li>Following baseline measurement collection (pre-intervention), begin the SSHM with the positioning of a soccer ball launcher approximately 40 ft away from the subject, as well as ensuring the soccer ball is inflated to 9 psi.</li>
	<li>The face of the machine displays two identical dials, which regulate the speed of the left and right wheels, and an on/off switch in between them. Set both these dials to a standardized speed of choice. 
	NOTE: For this demonstration purpose, the ball traveling speed has been set to 30 mph. This speed was chosen as it simulates a soccer throw-in from the sideline to midfield. Soccer players frequently perform this maneuver during practice and games.</li>
	<li>Place 3 inch blocks underneath the wheels of the ball launcher to allow for the desired trajectory (no blocks needed for kicking subjects). Once this is complete, the ball launcher is then angled to 40&#176;, which is measured as the angle between the ground and the midline of the rotating wheels. 
	NOTE: The angle measurement is taken with a goniometer, and the machine can be adjusted after loosening a knob located along the blue rails where the soccer ball is loaded.</li>
	<li>Once the soccer machine is properly set, fit the subjects with a triaxial accelerometer embedded within a head-band pocket and positioned directly below the external occipital protuberance (inion) to monitor linear and rotational head accelerations.</li>
	<li>Start up the corresponding software for the accelerometer, and enter the subject&#8217;s information accordingly. At this point, the subject is ready to begin the familiarization trials of the intervention (heading, kicking).</li>
</ol>
2. Familiarization trials
<ol>
	<li>Position the subject approximately 40 ft in front of the ball launcher.</li>
	<li>Be sure to explain to the subject that the ball launcher will volley the soccer ball to them and that they simply need to simulate intervention contact with the ball (i.e., heading subjects will catch the ball with their hands in front of their forehead before head-to-ball contact is made, kicking subjects will &#8220;trap&#8221; the ball on the ground with their foot instead of volleying the ball back, and standing subjects will remain static and not make contact with the ball).</li>
	<li>When the subject understands and feels ready, have the researcher turn the ball launcher on, load the soccer ball onto the blue rails, and finally push the ball into the rotating wheels after a 3-2-1 countdown.</li>
	<li>After stopping the ball as described previously (step 2.2), have the subject roll the ball back.</li>
	<li>Repeat steps 2.3 and 2.4 two to four additional times (no rest time required between) to ensure that the subject positioning is correct and interaction with the ball will be safe and controlled. This concludes the familiarization trials.</li>
</ol>
3. Intervention
<ol>
	<li>Verbally confirm that the subject is ready. Once confirmed, give instructions to the heading subjects to only make forehead contact with the ball; tell the subjects to avoid potential impacts to the crown, parietal, and temporal lobes. Instruct the kicking subjects to kick the ball only while it is in flight as ball contact with the ground will attenuate the subsequent impact to the foot.</li>
	<li>Instruct both heading and kicking subjects to volley the ball to a target (additional researcher) approximately half the distance between them and the machine. As best they can, ask subjects to do this in a manner that will mimic the arched trajectory the ball took during its flight toward the subject.</li>
	<li>Activate the triaxial accelerometer and begin the recording.</li>
	<li>Load the soccer ball onto the blue rails, push the ball into the rotating wheels after a 3-2-1 countdown, and make sure appropriate contact is made.</li>
	<li>Repeat step 3.4 nine more times with a 60 s rest in between bouts. If the subject forgoes interaction with the ball (due to inopportune placement or suspected contact with the body in an area that must be avoided), then volley the ball to the subject again promptly, without any rest period.</li>
	<li>In between each head contact with the ball, verify that the triaxial accelerometer registered an impact (using triaxial software; kicking subjects should not register G-force).</li>
	<li>Once the intervention is concluded, turn off the ball launcher and stop the triaxial recording (important, as the movement required to remove the headband could record another &#8220;impact&#8221;). Once the recording has stopped, remove the headband.</li>
</ol>

<ol>
	<li>Goldstein, L. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+traumatic+encephalopathy+in+blast-exposed+military+veterans+and+a+blast+neurotrauma+mouse+model.">Chronic traumatic encephalopathy in blast-exposed military veterans and a blast neurotrauma mouse model.</a> Science Translational Medicine. 4 (134), 134ra60 (2012).</li><li>Kraus, M. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=White+matter+integrity+and+cognition+in+chronic+traumatic+brain+injury:+a+diffusion+tensor+imaging+study.">White matter integrity and cognition in chronic traumatic brain injury: a diffusion tensor imaging study.</a> Brain: A Journal of Neurology. 130 (Pt 10), 2508-2519 (2007).</li><li>McKee, A. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+spectrum+of+disease+in+chronic+traumatic+encephalopathy.">The spectrum of disease in chronic traumatic encephalopathy.</a> Brain: A Journal of Neurology. 136 (Pt. 136 (Pt 1), 43-64 (2013).</li><li>Mez, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinicopathological+Evaluation+of+Chronic+Traumatic+Encephalopathy+in+Players+of+American+Football.">Clinicopathological Evaluation of Chronic Traumatic Encephalopathy in Players of American Football.</a> JAMA. 318 (4), 360-370 (2017).</li><li>Tagge, C. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concussion,+microvascular+injury,+and+early+tauopathy+in+young+athletes+after+impact+head+injury+and+an+impact+concussion+mouse+model.">Concussion, microvascular injury, and early tauopathy in young athletes after impact head injury and an impact concussion mouse model.</a> Brain: A Journal of Neurology. 141 (2), 422-458 (2018).</li><li>Bailes, J. E., Petraglia, A. L., Omalu, B. I., Nauman, E., Talavage, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+subconcussion+in+repetitive+mild+traumatic+brain+injury.">Role of subconcussion in repetitive mild traumatic brain injury.</a> Journal of Neurosurgery. 119 (5), 1235-1245 (2013).</li><li>Schnebel, B., Gwin, J. T., Anderson, S., Gatlin, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+study+of+head+impacts+in+football:+a+comparison+of+National+Collegiate+Athletic+Association+Division+I+versus+high+school+impacts.">In vivo study of head impacts in football: a comparison of National Collegiate Athletic Association Division I versus high school impacts.</a> Neurosurgery. 60 (3), 490-496 (2007).</li><li>Guskiewicz, K. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+head+impacts+in+collegiate+football+players:+relationship+between+head+impact+biomechanics+and+acute+clinical+outcome+after+concussion.">Measurement of head impacts in collegiate football players: relationship between head impact biomechanics and acute clinical outcome after concussion.</a> Neurosurgery. 61 (6), 1244-1253 (2007).</li><li>Combat veterans coming home with CTE. CBS News Available from: <a target="_blank" href="https://www.cbsnews.com/news/60-minutes-combat-veterans-coming-home-with-cte-brain-injury/">https://www.cbsnews.com/news/60-minutes-combat-veterans-coming-home-with-cte-brain-injury/</a> (2018)</li><li>Ward, J., Williams, J., Manchester, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=111+N.F.L.+Brains.+All+But+One+Had+C.T.E.">111 N.F.L. Brains. All But One Had C.T.E.</a> The New York Times. , (2017).</li><li>Ling, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mixed+pathologies+including+chronic+traumatic+encephalopathy+account+for+dementia+in+retired+association+football+(soccer)+players.">Mixed pathologies including chronic traumatic encephalopathy account for dementia in retired association football (soccer) players.</a> Acta Neuropathologica. 133 (3), 337-352 (2017).</li><li>Kawata, K., Tierney, R., Phillips, J., Jeka, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+Repetitive+Sub-concussive+Head+Impacts+on+Ocular+Near+Point+of+Convergence.">Effect of Repetitive Sub-concussive Head Impacts on Ocular Near Point of Convergence.</a> International Journal of Sports Medicine. 37 (5), 405-410 (2016).</li><li>Wirsching, A., Chen, Z., Bevilacqua, Z. W., Huibregtse, M. E., Kawata, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Association+of+Acute+Increase+in+Plasma+Neurofilament+Light+with+Repetitive+Subconcussive+Head+Impacts:+A+Pilot+Randomized+Control+Trial.">Association of Acute Increase in Plasma Neurofilament Light with Repetitive Subconcussive Head Impacts: A Pilot Randomized Control Trial.</a> Journal of Neurotrauma. , (2018).</li><li>Coon, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Acute Effects of Sleep Deprivation on Ocular-Motor Function as Assessed by King-Devick Test Performance. , (2018).</li><li>Hwang, S., Ma, L., Kawata, K., Tierney, R., Jeka, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vestibular+Dysfunction+after+Subconcussive+Head+Impact.">Vestibular Dysfunction after Subconcussive Head Impact.</a> Journal of Neurotrauma. 34 (1), 8-15 (2017).</li><li>Oliver, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serum+Neurofilament+Light+in+American+Football+Athletes+over+the+Course+of+a+Season.">Serum Neurofilament Light in American Football Athletes over the Course of a Season.</a> Journal of Neurotrauma. 33 (19), 1784-1789 (2016).</li><li>Shahim, P., Zetterberg, H., Tegner, Y., Blennow, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serum+neurofilament+light+as+a+biomarker+for+mild+traumatic+brain+injury+in+contact+sports.">Serum neurofilament light as a biomarker for mild traumatic brain injury in contact sports.</a> Neurology. 88 (19), 1788-1794 (2017).</li><li>FIFA Communications Division, Information Services. FIFA Big Count 2006: 270 million people active in football Available from: <a target="_blank" href="https://www.fifa.com/mm/document/fifafacts/bcoffsurv/bigcount.statspackage_7024.pdf">https://www.fifa.com/mm/document/fifafacts/bcoffsurv/bigcount.statspackage_7024.pdf</a> (2007)</li><li>Dorminy, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+soccer+heading+ball+speed+on+S100B,+sideline+concussion+assessments+and+head+impact+kinematics.">Effect of soccer heading ball speed on S100B, sideline concussion assessments and head impact kinematics.</a> Brain Injury. , 1-7 (2015).</li><li>Bretzin, A. C., Mansell, J. L., Tierney, R. T., McDevitt, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sex+Differences+in+Anthropometrics+and+Heading+Kinematics+Among+Division+I+Soccer+Athletes.">Sex Differences in Anthropometrics and Heading Kinematics Among Division I Soccer Athletes.</a> Sports Health. 9 (2), 168-173 (2017).</li><li>Crisco, J. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Frequency+and+location+of+head+impact+exposures+in+individual+collegiate+football+players.">Frequency and location of head impact exposures in individual collegiate football players.</a> Journal of Athletic Training. 45 (6), 549-559 (2010).</li><li>Duma, S. 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B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Practice+type+effects+on+head+impact+in+collegiate+football.">Practice type effects on head impact in collegiate football.</a> Journal of Neurosurgery. , 1-10 (2015).</li><li>Kawata, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Association+of+Football+Subconcussive+Head+Impacts+With+Ocular+Near+Point+of+Convergence.">Association of Football Subconcussive Head Impacts With Ocular Near Point of Convergence.</a> JAMA Ophthalmology. 134 (7), 763-769 (2016).</li><li>Wilcox, B. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Head+impact+exposure+in+male+and+female+collegiate+ice+hockey+players.">Head impact exposure in male and female collegiate ice hockey players.</a> Journal of Biomechanics. 47 (1), 109-114 (2014).</li><li>Wallace, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heading+in+soccer+increases+serum+neurofilament+light+protein+and+SCAT3+symptom+metrics.">Heading in soccer increases serum neurofilament light protein and SCAT3 symptom metrics.</a> BMJ Open Sport &amp; Exercise Medicine. 4 (1), e000433 (2018).</li></ol>

The authors have nothing to disclose.

While contact sports like American football might appear to be driving the need for a concise research model to study subconcussive impacts, other sports like soccer may account for the dominant share of subconcussive exposure around the globe as approximately 265 million people participate in what is perhaps the world&#8217;s most popular sport19. However, while the majority of the suspected long-term neurodegenerative effects of subconcussion have been autopsied in American football players, the...

Long-term, repetitive exposure to subconcussive head impacts has been proposed as one of the key contributors for developing the neurodegenerative disease CTE1,2,3,4,5. Each year, approximately 2.5 million high school and college athletes engage in contact sports that frequently induce these subconcussive insults through rapid acceleration-deceleration of the body and head6,7. Specifically, contact sport athletes may experience several 100 up to a 1,000 of such impacts per season6,8,9. Additionally, other populations, such as military men and women, have registered more than 300,000 head injuries since 2001, which has manifested into the recent diagnosis of CTE within a retired military veteran10. This diagnosis parallels with 110 postmortem CTE brains of American football players and four postmortem soccer players to present a burgeoning public health issue11,12. In light of the staggering prevalence, head impact research must shift its gaze to incorporate sound, precise methods of analyzing the acute debt subconcussive hits are inducing in a variety of arenas.
The SSHM presented here is one that satisfies the current methodological need to safely induce common mechanical stresses placed upon neural tissue during contact sport activities. The implementation of this model allows investigators to meticulously manage ball traveling speed, the frequency of impacts, interval, ball placement to the head, as well as measurements of head impact magnitude13,14. While these factors are virtually impossible to control in the field setting, the SSHM provides an outlet for researchers to isolate the effects of subconcussive head impacts. Furthermore, through the elimination of confounding variables seen during play (e.g., effects from vigorous exercise, body damage, body temperature change, and hydration/perspiration), the SSHM provides a superior method of validating clinical observations.
The SSHM has direct parallels to head impacts seen specifically within the realm of sport. As such, the literature has already begun to show its utility and corroborate the findings of cumulative head impact burden from other investigators. For example, we have demonstrated that the burden of subconcussive head impacts significantly drive neuro-ophthalmologic dysfunction amongst soccer athletes13,15. In addition, as few as 10 subconcussive impacts have been shown to immediately perturb vestibular function which can be normalized after 24 h of resting16. In this methodological report, we describe the application of SSHM to safely study the effects of subconcussive head impacts and introduce one of our findings that repetitive subconcussive head impacts gradually increase the concentration of a neuron-derived blood biomarker, namely NF-L14. This finding not only substantiates previous results of NF-L presence due to repetitive subconcussive blows to the head17,18 but also validates that the SSHM can reproduce such findings in a controlled clinical manner.

<table><tbody><tr><td>JUGS Soccer Machine</td><td>JUGS Sports</td><td>http://jugssports.com/products/soccer-machine.html</td><td></td></tr><tr><td>SIM-G Triaxial Accelerometer</td><td>Triax Technologies</td><td>https://www.triaxtec.com/workersafety/wp-content/uploads/2017/08/SIM-G-User-Manual_V4-2-01.pdf</td><td></td></tr></tbody></table>

in vivo protocol of controlled subconcussive head impacts for the validation of field study data

Subconcussive hits pose a threat to neuronal health as they have shown to induce neuronal structural damage and functional impairment without causing outward symptomology and appear to be a key contributor to an irreversible neurodegenerative disease, chronic traumatic encephalopathy (CTE). In addition, athletes can incur more than 1,000 of these hits per season. The subconcussive soccer heading model (SSHM) is a relevant, reproducible, and leading method of isolating and examining the effects of these subconcussive head impacts. By controlling variables such as ball traveling speed, the frequency of impacts, interval, ball placement to the head, as well as by measuring head impact magnitude, the SSHM provides the scientific community with a superior avenue of investigating the acute subconcussive effects on neuronal health. In this paper, we demonstrate the utility of SSHM in studying a time-course expression of neurofilament-light polypeptide (NF-L) in plasma in a repeated measures fashion. NF-L is an axonal injury marker that has previously been shown to be elevated in boxers and football players following subconcussive head trauma. Thirty-four adult aged soccer players were recruited and randomly assigned to either a soccer heading (n = 18) or kicking (n = 16) group. The heading group executed 10 headers with soccer balls projected at a velocity of 25 mph over 10 min. The kicking group followed the same protocol with 10 kicks. Plasma samples were obtained before and at 0 h, 2 h, and 24 h after heading/kicking and assessed for NF-L expressions. The heading group showed a gradual increase in plasma NF-L expression and peaked at 24 h after the heading protocol, whereas the kicking group remained consistent across the time points. These results confirmed the NF-L data from clinical field studies, encouraging the use of SSHM to validate clinical subconcussion data.

The results represented here were interpreted from a previous article14, in which the SSHM was utilized as previously described. In this particular study, we aimed to show how the SSHM could induce changes in plasma levels of NF-L, which is an axonal injury marker that is hypothesized to filter out of the cranium and into the peripheral blood following head impacts.
SSHM and head kinematics</stron...

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In Vivo Protocol of Controlled Subconcussive Head Impacts for the Validation of Field Study Data

The subconcussive soccer heading model is a safe and concise methodological approach to isolate and measure the effects of subconcussive head impacts.

Subconcussive hits pose a threat to neuronal health as they have shown to induce neuronal structural damage and functional impairment without causing ...

in-vivo-protocol-controlled-subconcussive-head-impacts-for-validation

Research

JoVE Journal

Behavior

6.3K Views.  Indiana University. The subconcussive soccer heading model is a safe and concise methodological approach to isolate and measure the effects of subconcussive head impacts.

Video: In Vivo Protocol of Controlled Subconcussive Head Impacts for the Validation of Field Study Data

An Investigation of the Effects of Sports-related Concussion in Youth Using Functional Magnetic Resonance Imaging and the Head Impact Telemetry System

One of the most commonly reported injuries in children who participate in sports is concussion or mild traumatic brain injury (mTBI)1. Children and youth involved in organized sports such as competitive hockey are nearly six times more likely to suffer a severe concussion compared to children involved in other leisure physical activities2. While the most common cognitive sequelae of mTBI appear similar for children and adults, the recovery profile and breadth of consequences in children remains largely unknown2, as does the influence of pre-injury characteristics (e.g. gender) and injury details (e.g. magnitude and direction of impact) on long-term outcomes. Competitive sports, such as hockey, allow the rare opportunity to utilize a pre-post design to obtain pre-injury data before concussion occurs on youth characteristics and functioning and to relate this to outcome following injury. Our primary goals are to refine pediatric concussion diagnosis and management based on research evidence that is specific to children and youth. To do this we use new, multi-modal and integrative approaches that will:
 1.Evaluate the immediate effects of head trauma in youth 
2.Monitor the resolution of post-concussion symptoms (PCS) and cognitive performance during recovery 
3.Utilize new methods to verify brain injury and recovery
To achieve our goals, we have implemented the Head Impact Telemetry (HIT) System. (Simbex; Lebanon, NH, USA). This system equips commercially available Easton S9 hockey helmets (Easton-Bell Sports; Van Nuys, CA, USA) with single-axis accelerometers designed to measure real-time head accelerations during contact sport participation 3 - 5. By using telemetric technology, the magnitude of acceleration and location of all head impacts during sport participation can be objectively detected and recorded. We also use functional magnetic resonance imaging (fMRI) to localize and assess changes in neural activity specifically in the medial temporal and frontal lobes during the performance of cognitive tasks, since those are the cerebral regions most sensitive to concussive head injury 6. Finally, we are acquiring structural imaging data sensitive to damage in brain white matter.

This article provides an overview of a multi-modal approach to mild traumatic brain injury diagnosis and recovery in youth. This approach combines neuropsychological testing with functional magnetic resonance imaging and the Head Impact Telemetry System to monitor the relationship between head impacts and brain activity during cognitive testing.

One of the most commonly reported injuries in children who participate in sports is concussion or mild traumatic brain injury (mTBI)1. Children and youth ...

Medicine

Modified Drop Tower Impact Tests for American Football Helmets

A modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test method for American football helmet drop impact test standards is presented that would provide better assessment of a helmet's on-field impact performance by including a faceguard on the helmet. In this study, a merger of faceguard and helmet test standards is proposed. The need for a more robust systematic approach to football helmet testing procedures is emphasized by comparing representative results of the Head Injury Criterion (HIC), Severity Index (SI), and peak acceleration values for different helmets at different helmet locations under modified NOCSAE standard drop tower tests. Essentially, these comparative drop test results revealed that the faceguard adds a stiffening kinematic constraint to the shell that lessens total energy absorption. The current NOCSAE standard test methods can be improved to represent on-field helmet hits by attaching the faceguards to helmets and by including two new helmet impact locations (Front Top and Front Top Boss). The reported football helmet test method gives a more accurate representation of a helmet's performance and its ability to mitigate on-field impacts while promoting safer football helmets.

This article provides a novel technique to assess the performance characteristics of American football helmets by inclusion of faceguards during NOCSAE Standard drop tests. Additionally, two more impact locations are proposed to be added to the NOCSAE certification.

A modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test method for American football helmet drop impact test standards ...

Bioengineering

A Test Bed to Examine Helmet Fit and Retention and Biomechanical Measures of Head and Neck Injury in Simulated Impact

Conventional wisdom and the language in international helmet testing and certification standards suggest that appropriate helmet fit and retention during an impact are important factors in protecting the helmet wearer from impact-induced injury. This manuscript aims to investigate impact-induced injury mechanisms in different helmet fit scenarios through analysis of simulated helmeted impacts with an anthropometric test device (ATD), an array of headform acceleration transducers and neck force/moment transducers, a dual high speed camera system, and helmet-fit force sensors developed in our research group based on Bragg gratings in optical fiber. To simulate impacts, an instrumented headform and flexible neck fall along a linear guide rail onto an anvil. The test bed allows simulation of head impact at speeds up to 8.3 m/s, onto impact surfaces that are both flat and angled. The headform is fit with a crash helmet and several fit scenarios can be simulated by making context specific adjustments to the helmet position index and/or helmet size. To quantify helmet retention, the movement of the helmet on the head is quantified using post-hoc image analysis. To quantify head and neck injury potential, biomechanical measures based on headform acceleration and neck force/moment are measured. These biomechanical measures, through comparison with established human tolerance curves, can estimate the risk of severe life threatening and/or mild diffuse brain injury and osteoligamentous neck injury. To our knowledge, the presented test-bed is the first developed specifically to assess biomechanical effects on head and neck injury relative to helmet fit and retention.

Using an anthropometric head and neck, optical fiber-based fit force transducers, an array of head acceleration and neck force/moment transducers, and a dual high speed camera system, we present a test bed to study helmet retention and effects on biomechanical measures of head and neck injury secondary to head impact.

Conventional wisdom and the language in international helmet testing and certification standards suggest that appropriate helmet fit and retention during ...

A Repetitive Concussive Head Injury Model in Mice

Despite the concussion/ mild traumatic brain injury (mTBI) being the most frequent occurrence of traumatic brain injury, there is still a lack of knowledge on the injury and its effects. To develop a better understanding of concussions, animals are often used because they provide a controlled, rigorous, and efficient model. Studies have adapted traditional animal models to perform mTBI to stimulate mild injury severity by changing the injury parameters. These models have been used because they can produce morphologically similar brain injuries to the clinical condition and provide a spectrum of injury severities. However, they are limited in their ability to present the identical features of injuries in patients. Using a traditional impact system, a repetitive concussive injury (rCHI) model can induce mild to moderate human-like concussion. The injury degree can be determined by measuring the period of loss of consciousness (LOC) with a sign of a transient termination of breathing. The rCHI model is beneficial to use for its accuracy and simplicity in determining mTBI effects and potential treatments.

Concussion presents the most common type of traumatic brain injury. Therefore, a repetitive concussive animal model, which replicates the important features of an injury in patients, may provide a means to study concussion in a rigorous, controlled, and efficient manner.

Despite the concussion/ mild traumatic brain injury (mTBI) being the most frequent occurrence of traumatic brain injury, there is still a lack of ...

A Novel and Translational Rat Model of Concussion Combining Force and Rotation with In Vivo Cerebral Microdialysis

Persistent cognitive and motor symptoms are known consequences of concussions/mild traumatic brain injury (mTBIs) that can be partly attributable to altered neurotransmission. Indeed, cerebral microdialysis studies in rodents have demonstrated an excessive extracellular glutamate release in the hippocampus within the first 10 min following trauma. Microdialysis offers the clear advantage of in vivo neurotransmitter continuous sampling while not having to sacrifice the animal. In addition to the aforementioned technique, a closed head injury model that exerts rapid acceleration and deceleration of the head and torso is needed, as such a factor is not available in many other animal models. The Wayne State weight-drop model mimics this essential component of human craniocerebral trauma, allowing the induction of an impact on the head of an unrestrained rodent with a falling weight. Our novel and translational rat model combines cerebral microdialysis with the Wayne State weight-drop model to study, in lightly anesthetized and unrestrained adult rats, the acute changes in extracellular neurotransmitter levels following concussion. In this protocol, the microdialysis probe was inserted inside the hippocampus as region of interest, and was left inserted in the brain at impact. There is a high density of terminals and receptors in the hippocampus, making it a relevant region to document altered neurotransmission following concussion. When applied to adult Sprague-Dawley rats, our combined model induced increases in hippocampal extracellular glutamate concentrations within the first 10 min, consistent with the previously reported post-concussion symptomology. This combined weight-drop model provides a reliable tool for researchers to study early therapeutic responses to concussions in addition to repetitive brain injury, since this protocol induces a closed-head mild trauma.

Neurotransmitter alteration is a mechanism of neural dysfunction that occurs after concussion and contributes to the sometimes-catastrophic long-term consequences. This rat model combines microdialysis, allowing in vivo neurotransmitter quantification, with a weight-drop technique exerting rapid acceleration and deceleration of the head and torso, an important factor of human craniocerebral trauma.

Persistent cognitive and motor symptoms are known consequences of concussions/mild traumatic brain injury (mTBIs) that can be partly attributable to ...

Neuroscience

Murine Model of Controlled Cortical Impact for the Induction of Traumatic Brain Injury

The Centers for Disease Control and Injury Prevention estimate that almost 2 million people sustain a traumatic brain injury (TBI) every year in the United States. In fact, TBI is a contributing factor to over a third of all injury-related mortality. Nonetheless, the cellular and molecular mechanisms underlying the pathophysiology of TBI are poorly understood. Thus, preclinical models of TBI capable of replicating the injury mechanisms pertinent to TBI in human patients are a critical research need. The controlled cortical impact (CCI) model of TBI utilizes a mechanical device to directly impact the exposed cortex. While no model can full recapitulate the disparate injury patterns and heterogeneous nature of TBI in human patients, CCI is capable of inducing a wide range of clinically applicable TBI. Furthermore, CCI is easily standardized allowing investigators to compare results across experiments as well as across investigative groups. The following protocol is a detailed description of applying a severe CCI with a commercially available impacting device in a murine model of TBI.

Here we describe a protocol for the induction of murine traumatic brain injury via an open-head controlled cortical impact.

The Centers for Disease Control and Injury Prevention estimate that almost 2 million people sustain a traumatic brain injury (TBI) every year in the ...

Low-intensity Blast Wave Model for Preclinical Assessment of Closed-head Mild Traumatic Brain Injury in Rodents

Traumatic brain injury (TBI) is a large-scale public health problem. Mild TBI is the most prevalent form of neurotrauma and accounts for a large number of medical visits in the United States. There are currently no FDA-approved treatments available for TBI. The increased incidence of military-related, blast-induced TBI further accentuates the urgent need for effective TBI treatments. Therefore, new preclinical TBI animal models that recapitulate aspects of human blast-related TBI will greatly advance the research efforts into the neurobiological and pathophysiological processes underlying mild to moderate TBI as well as the development of novel therapeutic strategies for TBI.
Here we present a reliable, reproducible model for the investigation of the molecular, cellular, and behavioral effects of mild to moderate blast-induced TBI. We describe a step-by-step protocol for closed-head, blast-induced mild TBI in rodents using a bench-top setup consisting of a gas-driven shock tube equipped with piezoelectric pressure sensors to ensure consistent test conditions. The benefits of the setup that we have established are its relative low-cost, ease of installation, ease of use and high-throughput capacity. Further advantages of this non-invasive TBI model include the scalability of the blast peak overpressure and the generation of controlled reproducible outcomes. The reproducibility and relevance of this TBI model has been evaluated in a number of downstream applications, including neurobiological, neuropathological, neurophysiological and behavioral analyses, supporting the use of this model for the characterization of processes underlying the etiology of mild to moderate TBI.

We present here a protocol of a blast wave model for rodents to investigate neurobiological and pathophysiological effects of mild to moderate traumatic brain injury. We established a gas-driven, bench-top setup equipped with pressure sensors allowing for reliable and reproducible generation of blast-induced mild to moderate traumatic brain injury.

Traumatic brain injury (TBI) is a large-scale public health problem. Mild TBI is the most prevalent form of neurotrauma and accounts for a large number of ...

Objectively Assessing Sports Concussion Utilizing Visual Evoked Potentials

A portable system capable of measuring steady-state visual-evoked potentials (SSVEP) was developed to provide an objective, quantifiable method of electroencephalogram (EEG) testing following a traumatic event. In this study, the portable system was used on 65 healthy rugby players throughout a season to determine whether SSVEP are a reliable electrophysiological biomarker for concussion. Preceding the competition season, all players underwent a baseline SSVEP assessment. During the season, players were re-tested within 72 h of a match for either test-retest reliability or post-injury assessment. In the case of a medically diagnosed concussion, players were reassessed again once deemed recovered by a physician. The SSVEP system consisted of a smartphone housed in a VR-frame delivering a 15 Hz flicker stimulus, while a wireless EEG headset recorded occipital activity. Players were instructed to stare at the screen's fixation point while remaining seated and quiet. Electrodes were arranged according to the 10-20 EEG-positioning nomenclature, with O1-O2 being the recording channels while P1-P2 the references and bias, respectively. All EEG data was processed using a Butterworth bandpass filter, Fourier transformation, and normalization to convert data for frequency analysis. Players SSVEP responses were quantified into a signal-to-noise ratio (SNR), with 15 Hz being the desired signal, and summarized into respective study groups for comparison. Concussed players were seen to have a significantly lower SNR compared to their baseline; however, post-recovery, their SNR was not significantly different from the baseline. Test-retest indicated high device reliability for the portable system. An improved portable SSVEP system was also validated against an established EEG amplifier to ensure the investigative design is capable of obtaining research quality EEG measurements. This is the first study to identify differences in SSVEP responses in amateur athletes following a concussion and indicates the potential for SSVEP as an aid in concussion assessment and management.

A portable system capable of measuring steady-state visual-evoked potentials was developed and trialed on 65 amateur rugby players over 18 weeks to investigate SSVEP as a potential electrophysiological biomarker for concussion. Players' baselines were measured pre-season, with retesting for reliability, concussion, and recovery assessment being conducted within controlled time-periods, respectively.

A portable system capable of measuring steady-state visual-evoked potentials (SSVEP) was developed to provide an objective, quantifiable method of ...

A Preclinical Controlled Cortical Impact Model for Traumatic Hemorrhage Contusion and Neuroinflammation

Cerebral contusion is a severe medical problem affecting millions of people worldwide each year. There is an urgent need to understand the pathophysiological mechanism and to develop effective therapeutic strategy for this devastating neurological disorder. Intraparenchymal hemorrhage and post-traumatic inflammatory response induced by initial physical impact can aggravate microglia/macrophage activation and neuroinflammation which subsequently worsen brain pathology. We provide here a controlled cortical impact (CCI) protocol that can reproduce experimental cortical contusion in mice by using a pneumatic impactor system to deliver mechanical force with controllable magnitude and velocity onto the dural surface. This preclinical model allows researchers to induce moderately severe focal cerebral contusion in mice and to investigate a wide range of post-traumatic pathological progressions including hemorrhage contusion, microglia/macrophage activation, iron toxicity, axonal injury, as well as short-term and long-term neurobehavioral deficits. The present protocol can be useful for exploring the long-term effects of and potential interventions for cerebral contusion.

Intraparenchymal hemorrhage and neuroinflammation accompanied by cerebral contusion can trigger severe secondary brain injury. This protocol details a mouse controlled cortical impact (CCI) model allowing researchers to study hemorrhage contusion and post-traumatic immune responses and explore potential therapeutics.

Cerebral contusion is a severe medical problem affecting millions of people worldwide each year. There is an urgent need to understand the ...

CHILD Model &#8212; Recapitulating Juvenile Concussion and Long-Term Outcomes in Mice

A Pediatric Concussion Model in Mice: Closed Head Injury with Long-Term Disorders (CHILD)

Concussions and mild traumatic brain injuries (mTBI) during childhood represent a significant health endangerment, with many patients later in life exhibiting debilitating physiological, neurological, and psychosocial outcomes. The cellular and molecular pathophysiological mechanisms are relatively unknown, and this significant gap effectively precludes investigations into specific therapeutic strategies to mitigate chronic sequelae. No single animal concussion model recapitulates all the features reported in human subjects, and current models are designed to answer specific research questions. We set out to develop a juvenile concussion that recapitulates clinical early, and long-term symptomology encountered, termed Closed Head Injury with Long-term Disorder (CHILD). In this model, a concussive force via an electromagnetic impactor is delivered to the head of a lightly anesthetized unrestrained post-natal day 17 (P17) mouse, allowing free rotation of the head. Mice are placed on a tightly stretched tin foil across a stereotactic device, and the impactor is carefully aligned with the targeted cortical region. The electromagnetic impactor facilitates the selection of impact depth, dwell, and duration to determine injury severity. A strength of this model is that it allows head rotation, an important clinical feature. After impact, mice are immediately monitored for righting time and time to explore their environment, followed by their return to their dam. Increasing the severity of concussion results in intracranial bleeds in a subset of mice. Mice can be routinely monitored for behavior and neuroimaging over their lifespan, as desired. Various injury severities mimic the heterogeneous nature of juvenile concussions. The current standard CHILD model exhibits no skull fracture, no observable conventional neuroimaging change (similar to clinical), but leads to progressive and persistent neuronal death, altered diffusion MRI, modified neuronal activity and plasticity, increased gliosis, and progressive behavioral perturbations with age. In summary, this CHILD model mimics the early and long-term features observed in many clinical concussion patients.

Pediatric concussions can result in long-term sequelae with physiological and psychological perturbations. This pediatric concussion mouse model results in long-term neuroinflammation, white matter alterations, and neuronal modifications with behavioral dysfunction. The model can be adapted to differential impact locations or repeated concussions to assess lifetime changes.

Concussions and mild traumatic brain injuries (mTBI) during childhood represent a significant health endangerment, with many patients later in life ...