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 be...

<ol>
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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. 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=Analysis+of+real-time+head+accelerations+in+collegiate+football+players.">Analysis of real-time head accelerations in collegiate football players.</a> Clinical Journal of Sport Medicine. 15 (1), 3-8 (2005).</li><li>Reynolds, B. 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.

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			<td height="23" style="height:23px;width:216px;">JUGS Soccer Machine</td>
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			<td height="23" style="height:23px;width:216px;">SIM-G Triaxial Accelerometer</td>
			<td style="width:179px;">Triax Technologies</td>
			<td style="width:705px;">https://www.triaxtec.com/workersafety/wp-content/uploads/2017/08/SIM-G-User-Manual_V4-2-01.pdf</td>
			<td></td>
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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 ...

Repetitive head impacts are a complex public health problem. This protocol is a safe and reproducible method for validating whether clinical findings are due to head impacts or noise factor. From ball speed and impact placement to exercise effect and body temperature, this model gives researchers a comprehensive method for studying subconcussive head impacts.This model allows researchers to validate clinical findings beyond acute profiles of brain-derived blood biomarkers and be used to investigate perturbations in ocular motor function, the vestibular system, and more. During play, the head makes contact with the ball in various ways. Therefore, it's important to visualize what is meant by soccer heading model as described in the literature.Following baseline measurement collection pre-intervention, position a soccer ball launcher approximately 40 feet away from the subject. And confirm that the soccer balls to be used for the trial have been inflated to nine pounds per square inch. The face of the machine displays two identical dials that regulate the speed of the left and right wheels with an on/off switch in between.Set both of the dials to a standardized speed of choice and place three inch blocks under the wheels of the ball launcher to allow the desired trajectory. When the last block has been placed, angle the launcher to 40 degrees between the ground and the midline of the rotating wheels. Next, fit the subject with a triaxial accelerometer embedded with a headband pocket positioned directly below the external occipital protuberance to monitor the linear and rotational head accelerations.Before beginning the familiarization trials, explain to the subject that the ball launcher will volley the soccer ball and that contact with the ball simply needs to be simulated for the trials. Next, explain to the subject how contact should be made during the intervention trials. For example, heading subjects should only make forehead contact with the ball, avoiding potential impacts to the crown, parietal, and temporal bones.Lastly, kicking subjects should make lower limb contact with the ball while it is in flight. For example, heading subjects will catch the ball in front of the forehead before head to ball contact is made. And Kicking subjects will trap the ball on the ground with the foot instead of volleying the ball back.When the subject is ready, turn on the ball launcher and load a soccer ball onto the blue rails. Next, count down from three to one and push the ball into the rotating wheels. The subject should stop the ball as instructed.Then, have the subject roll the ball back and repeat the trial two to four more times to be sure that the subject positioning is correct and that the interaction with the ball will be safe and controlled. Once the subject feels comfortable with how proper contact is to be made, you may begin the intervention trials. If needed, reiterate to the subject what proper contact entails as seen previously.Next, instruct both heading and kicking subjects to volley the ball back to the target researcher approximately half the distance to the machine. Mimicking the trajectory of the ball during its flight towards the subject as closely as possible. Load the soccer ball onto the blue rails and push the ball into the rotating wheels after a three, two, one, countdown, making sure that an appropriate contact is made.Then repeat the intervention nine more times with a 60 second rest between bouts. When the intervention has concluded, turn off the ball launcher and stop the triaxial recording before removing the headband. These representative data were derived from 34 subjects.There were no significant differences in any demographic characteristics between the groups. The head impact kinematic data revealed that the heading group experienced a median linear head acceleration of 31.8 G force per head impact and a median rotational head impact of 3.56 kilo radians per second squared per head impact. In contrast, the control kicking group did not demonstrate detectable levels of head acceleration.There is a gradual increase in plasma neurofilament light polypeptide expression every hour after 10 headers in the kicking subjects with no similar significant time effect for the kicking control group. Follow up analysis further revealed that a significant difference appeared at 24 hours post-heading compared to pre-heading and compared to the kicking control group 24 hours after the intervention. Familiarization of the protocol will ensure the participant's safety and uniformed impact.Therefore, it is important to both describe and have each participant practice the heading technique until they are comfortable. This protocol is a powerful tool that can be used to validate neuroimaging, auditory responses, and protective gear assessment, as well as clinical trials on therapeutic factors.

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6.2K visualizações.  Indiana University. Os impactos repetitivos na cabeça são um problema complexo de saúde pública. Este protocolo é um método seguro e reprodutível para validar se os achados clínicos são devido a impactos na cabeça ou fator sonorismo. Desde a velocidade da bola e a colocação do impacto até o efeito de exercício e a temperatura corporal, este modelo dá aos pesquisadores um método abrangente para estudar impactos subconcussivos na cabeça.Este modelo permite que os pesquisadores validem achad...