Role of Helmet Fit on Angular and Linear Accelerations of Head in Ice Hockey

Hesam Sarvghad Moghaddam; Whitman Kwok

doi:doi:10.11648/j.ijbse.20190702.11

| Peer-Reviewed

Role of Helmet Fit on Angular and Linear Accelerations of Head in Ice Hockey

Hesam Sarvghad Moghaddam, Whitman Kwok

Published in International Journal of Biomedical Science and Engineering (Volume 7, Issue 2)

Received: 6 August 2019 Accepted: 23 August 2019 Published: 6 September 2019

Views: Downloads:

Download PDF

Share This Article

Twitter
Linked In
Facebook

Abstract

Increasing the protection efficiency of helmets is counted as the biggest challenge in ice hockey. The main objective of this study is twofold: first to understand the effect of fitting on the protection capability of ice hockey helmets, and second to determine a possible optimal fit with respect to minimum head accelerations. A purpose-built monorail drop tower was utilized to perform front and front boss impacts at a velocity of 4.47m/s on a custom headform outfitted with a commercial helmet (CCM Resistance) with no gap (tight fit), 2mm (regular fit), and 5 mm gaps (loose fit). It was observed that while in both impacts linear accelerations were lower for the regular fit model, the loose fit model predicted the lowest angular accelerations. A loosely-fitted helmet provides non-deterministic shifting upon impact which generally leads to a wider standard deviation of linear and angular accelerations. The results indicated that in front impacts while introducing a gap reduced the risk of focal injuries, only the loose fit model suggested lower risks of concussive injuries. However, the regular and loose fit models showed better protection against focal and concussive injuries in the front boss impacts, respectively.

Published in	International Journal of Biomedical Science and Engineering (Volume 7, Issue 2)
DOI	10.11648/j.ijbse.20190702.11
Page(s)	26-32
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2024. Published by Science Publishing Group

Keywords

Ice Hockey, Helmet, Fitting, Concussion, Head Acceleration

References

[1]	Wennberg, R. and Tator, C. National Hockey League reported concussions, 1986-87 to 2001-02. Canadian Journal of Neurological Sciences/Journal Canadien des Sciences Neurologiques, 2003. 30 (03): p. 206-209.
[2]	LaPrade, R., Wijdicks, C., and Spiridonov, S. A prospective study of injuries in NCAA intercollegiate ice-hockey goaltenders. Proceedings of Fifth International Symposium on Safety in Ice Hockey, 2009.
[3]	Hutchison, M. G., Comper, P., Meeuwisse, W. H., and Echemendia, R. J. A systematic video analysis of National Hockey League (NHL) concussions, part I: who, when, where and what? British journal of sports medicine, 2013: p. bjsports-2013-092234.
[4]	Wilcox, B. J., Beckwith, J. G., et al. Biomechanics of head impacts associated with diagnosed concussion in female collegiate ice hockey players. Journal of biomechanics, 2015. 48 (10): p. 2201-2204.
[5]	Daneshvar, D. H., Nowinski, C. J., McKee, A. C., and Cantu, R. C. The epidemiology of sport-related concussion. Clinics in sports medicine, 2011. 30 (1): p. 1-17.
[6]	Kontos, A. P., Elbin, R. J., et al. Incidence of Concussion in Youth Ice Hockey Players. Pediatrics, 2016.
[7]	Langlois, J. A., Rutland-Brown, W., and Wald, M. M. The epidemiology and impact of traumatic brain injury: a brief overview. The Journal of head trauma rehabilitation, 2006. 21 (5): p. 375-378.
[8]	Omalu, B I., DeKosky, S. T., et al. Chronic traumatic encephalopathy in a National Football League player. Neurosurgery, 2005. 57 (1): p. 128-134.
[9]	Rowson, S. and Duma, S. M. Brain injury prediction: assessing the combined probability of concussion using linear and rotational head acceleration. Annals of biomedical engineering, 2013. 41 (5): p. 873-882.
[10]	McCrory, P., Meeuwisse, W., et al. Consensus statement on concussion in sport: the 3rd International Conference on Concussion in Sport held in Zurich, November 2008. Journal of athletic training, 2009. 44 (4): p. 434-448.
[11]	Marshall, S., Bayley, M., McCullagh, S., Velikonja, D., and Berrigan, L. Clinical practice guidelines for mild traumatic brain injury and persistent symptoms. Canadian Family Physician, 2012. 58 (3): p. 257-267.
[12]	Schnebel, B., Gwin, J. T., Anderson, S., and Gatlin, R. In vivo study of head impacts in football: a comparison of National Collegiate Athletic Association Division I versus high school impacts. Neurosurgery, 2007. 60 (3): p. 490-496.
[13]	Guskiewicz, K. M. and Mihalik, J. P. Biomechanics of sport concussion: quest for the elusive injury threshold. Exercise and sport sciences reviews, 2011. 39 (1): p. 4-11.
[14]	Oeur, R. A., Zanetti, K., and Hoshizaki, T. B. Angular acceleration responses of American football, lacrosse and ice hockey helmets subject to low-energy impacts. Proceedings of Proceedings of the IRCOBI Conference, 2014.
[15]	McKee, A. C., Stein, T. D., et al. The spectrum of disease in chronic traumatic encephalopathy. Brain, 2013. 136 (1): p. 43-64.
[16]	Bailes, J. E., Petraglia, A. L., Omalu, B. I., Nauman, E., and Talavage, T. Role of subconcussion in repetitive mild traumatic brain injury: a review. Journal of neurosurgery, 2013. 119 (5): p. 1235-1245.
[17]	Post, A., Karton, C., Hoshizaki, T. B., and Gilchrist, M. D. Analysis of the protective capacity of ice hockey helmets in a concussion injury reconstruction. Proceedings of IRCOBI Conference, 2014.
[18]	Hoshizaki, T. B., Walsh, E., et al. The application of brain tissue deformation values in assessing the safety performance of ice hockey helmets. Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology, 2012. 226 (3-4): p. 226-236.
[19]	Hoshizaki, T. B., Post, A., Oeur, R. A., and Brien, S. E. Current and future concepts in helmet and sports injury prevention. Neurosurgery, 2014. 75: p. S136-S148.
[20]	King, A. I., Yang, K. H., Zhang, L., Hardy, W., and Viano, D. C. Is head injury caused by linear or angular acceleration. Proceedings of IRCOBI conference, 2003.
[21]	Greenwald, R. M., Gwin, J. T., Chu, J. J., and Crisco, J. J. Head impact severity measures for evaluating mild traumatic brain injury risk exposure. Neurosurgery, 2008. 62 (4): p. 789.
[22]	Gurdjian, E. S., Roberts, V., and Thomas, L. M. Tolerance curves of acceleration and intracranial pressure and protective index in experimental head injury. Journal of Trauma and Acute Care Surgery, 1966. 6 (5): p. 600-604.
[23]	Versace, J. A review of the severity index. 1971, SAE Technical Paper.
[24]	Giordano, C. and Kleiven, S. Evaluation of axonal strain as a predictor for mild traumatic brain injuries using finite element modeling. Stapp car crash journal, 2014. 58: p. 29.
[25]	Takhounts, E. G., Craig, M. J., Moorhouse, K., McFadden, J., and Hasija, V. Development of brain injury criteria (BrIC). Stapp car crash journal, 2013. 57: p. 243.
[26]	Clark, J. M., Post, A., Hoshizaki, T. B., and Gilchrist, M. D. Determining the relationship between linear and rotational acceleration and MPS for different magnitudes of classified brain injury risk in ice hockey. International Research Council on the Biomechanics of Injury (IRCOBI), Lyon (France), 2015.
[27]	Holbourn, A. Mechanics of head injuries. The Lancet, 1943. 242 (6267): p. 438-441.
[28]	Ommaya, A. and Hirsch, A. Tolerances for cerebral concussion from head impact and whiplash in primates. Journal of biomechanics, 1971. 4 (1): p. 13-21.
[29]	Clark, J. M., Post, A., Hoshizaki, T. B., and Gilchrist, M. D. The Association among Injury Metrics for Different Events in Ice Hockey Goaltender Impacts.
[30]	Post, A., De Grau, S., et al. Comparison of Helmeted Head Impact in Youth and Adult Ice Hockey.
[31]	Ackery, A., Provvidenza, C., and Tutor, C. H. Concussion in hockey: compliance with return to play advice and follow-up status. Canadian Journal of Neurological Sciences/Journal Canadien des Sciences Neurologiques, 2009. 36 (02): p. 207-212.
[32]	Benson, B. W., Meeuwisse, W. H., Rizos, J., Kang, J., and Burke, C. J. A prospective study of concussions among National Hockey League players during regular season games: the NHL-NHLPA Concussion Program. Canadian Medical Association Journal, 2011. 183 (8): p. 905-911.
[33]	Goodman, D., Gaetz, M., and Meichenbaum, D. Concussions in hockey: there is cause for concern. Medicine and science in sports and exercise, 2001. 33 (12): p. 2004-2009.
[34]	Carlson, S. The Influence of Neck Stiffness, Impact Location, and Angle on Peak Linear Acceleration, Shear Force, and Energy Loading Measures of Hockey Helmet Impacts. 2016.
[35]	Zerpa, C., Carlson, S., Elyasi, S., Przysucha, E., and Hoshizaki, T. Energy Dissipation Measures on a Hockey Helmet across Impact Locations. Journal of Safety Engineering, 2016. 5 (2): p. 27-35.
[36]	Berti, S. Design of a Neck-Support-Incorporated Helmet for Reducing the Risk of Concussion in Ice Hockey. 2015, WORCESTER POLYTECHNIC INSTITUTE.
[37]	Rousseau, P., Post, A., and Hoshizaki, T. The effects of impact management materials in ice hockey helmets on head injury criteria. Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology, 2009. 223 (4): p. 159-165.
[38]	Halstead, P. D., Alexander, C. F., Cook, E. M., and Drew, R. C., "Safety in Ice Hockey: Third Volume", ASTM International, 2000.
[39]	Spittle, E. K., Miller, D. J., Shipley Jr, B. W., and Kaleps, I. Hybrid II and hybrid III dummy neck properties for computer modeling. 1992, DTIC Document.
[40]	Rivara, F. P., Astley, S. J., Clarren, S. K., Thompson, D. C., and Thompson, R. S. Fit of bicycle safety helmets and risk of head injuries in children. Injury Prevention, 1999. 5 (3): p. 194-197.
[41]	Chang, L.-T., Chang, C. -H., and Chang, G. -L. Fit Effect of Motorcycle Helmet. JSME International Journal Series A Solid Mechanics and Material Engineering, 2001. 44 (1): p. 185-192.
[42]	Yu, W. -Y., Chen, C. -Y., Chiu, W.-T., and Lin, M. -R. Effectiveness of different types of motorcycle helmets and effects of their improper use on head injuries. International journal of epidemiology, 2011: p. dyr040.
[43]	Greenhill, D. A., Navo, P., et al. Inadequate Helmet Fit Increases Concussion Severity in American High School Football Players. Sports Health, 2016. 8 (3): p. 238-243.
[44]	Hopes, P. and Chinn, B. Helmets: a new look at design and possible protection. Proceedings of INTERNATIONAL IRCOBI CONFERENCE ON THE, 1989.
[45]	Gilchrist, A. and Mills, N. Impact deformation of ABS and GRP motorcycle helmet shells. Plastics rubber and composites processing and applications, 1994. 21 (3): p. 141-150.
[46]	MacAlister, A. Surrogate Head Forms for the Evaluation of Head Injury Risk. Proceedings 2013.
[47]	Coulson, N., Foreman, S., and Hoshizaki, T. Translational and rotational accelerations generated during reconstructed ice hockey impacts on a Hybrid III head form. Proceedings of Fifth International Symposium on Safety in Ice Hockey, 2009.
[48]	McIntosh, A. S. and Janda, D. Evaluation of cricket helmet performance and comparison with baseball and ice hockey helmets. British journal of sports medicine, 2003. 37 (4): p. 325-330.
[49]	Walsh, E. S., Rousseau, P., and Hoshizaki, T. B. The influence of impact location and angle on the dynamic impact response of a hybrid III headform. Sports Engineering, 2011. 13 (3): p. 135-143.
[50]	Mihalik, J. P., Beard, J. R., Petschauer, M. A., Prentice, W. E., and Guskiewicz, K. M. Effect of ice hockey helmet fit on cervical spine motion during an emergency log roll procedure. Clinical Journal of Sport Medicine, 2008. 18 (5): p. 394-398.
[51]	Petschauer, M. A. B., "Effectiveness of cervical spine stabilization during spine boarding of collegiate lacrosse athletes". 2006: University of North Carolina at Greensboro.
[52]	Sherbondy, P. S., Hertel, J. N., and Sebastianelli, W. J. The effect of protective equipment on cervical spine alignment in collegiate lacrosse players. The American journal of sports medicine, 2006. 34 (10): p. 1675-1679.
[53]	Allen, E. B., "The effect of lacrosse helmet fit on cervical spine movement during a prone log roll". 2010: THE UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL.
[54]	Daneshvar, D. H., Baugh, C. M., et al. Helmets and mouth guards: the role of personal equipment in preventing sport-related concussions. Clinics in sports medicine, 2011. 30 (1): p. 145-163.
[55]	Forbes, J. A., Awad, A. J., Zuckerman, S., Carr, K., and Cheng, J. S. Association between biomechanical parameters and concussion in helmeted collisions in American football: a review of the literature. Neurosurgical focus, 2012. 33 (6): p. E10.
[56]	Viano, D. C., Withnall, C., and Halstead, D. Impact performance of modern football helmets. Annals of biomedical engineering, 2012. 40 (1): p. 160-174.
[57]	Rowson, S., Duma, S. M., et al. Can helmet design reduce the risk of concussion in football? Technical note. Journal of neurosurgery, 2014. 120 (4): p. 919-922.
[58]	Jadischke, R. Football helmet fitment and its effect on helmet performance. 2012.
[59]	Morehouse, C., "Safety in Ice Hockey", ASTM International, 1989.
[60]	Emery, C. A. and Meeuwisse, W. H. Injury rates, risk factors, and mechanisms of injury in minor hockey. The American journal of sports medicine, 2006. 34 (12): p. 1960-1969.
[61]	Zhang, L., Yang, K. H., and King, A. I. A proposed injury threshold for mild traumatic brain injury. Journal of biomechanical engineering, 2004. 126 (2): p. 226-236.
[62]	Duma, S. M., Manoogian, S. J., et al. Analysis of real-time head accelerations in collegiate football players. Clinical Journal of Sport Medicine, 2005. 15 (1): p. 3-8.
[63]	Willinger, R. m. and Baumgartner, D. Human head tolerance limits to specific injury mechanisms. International journal of Crashworthiness, 2003. 8 (6): p. 605-617.
[64]	Rousseau, P., Post, A., and Hoshizaki, T. A comparison of peak linear and angular headform accelerations using ice hockey helmets. Proceedings of Fifth International Symposium on Safety in Ice Hockey, 2009.
[65]	Meaney, D. F. and Smith, D. H. Biomechanics of concussion. Clinics in sports medicine, 2011. 30 (1): p. 19-31.
[66]	Zhang, L., Yang, K. H., and King, A. I. Comparison of brain responses between frontal and lateral impacts by finite element modeling. Journal of neurotrauma, 2001. 18 (1): p. 21-30.
[67]	Sarvghad-Moghaddam, H., Karami, G., and Ziejewski, M. The effects of directionality of blunt impacts on mechanical response of the brain. Proceedings of ASME 2014 International Mechanical Engineering Congress and Exposition, Montreal, Canada, November 2014, 2014. Montreal, Canada.
[68]	Kimpara, H. and Iwamoto, M. Mild traumatic brain injury predictors based on angular accelerations during impacts. Annals of biomedical engineering, 2012. 40 (1): p. 114-126.

Cite This Article

Plain Text BibTeX RIS

APA Style

Hesam Sarvghad Moghaddam, Whitman Kwok. (2019). Role of Helmet Fit on Angular and Linear Accelerations of Head in Ice Hockey. International Journal of Biomedical Science and Engineering, 7(2), 26-32. https://doi.org/10.11648/j.ijbse.20190702.11

Copy | Download

ACS Style

Hesam Sarvghad Moghaddam; Whitman Kwok. Role of Helmet Fit on Angular and Linear Accelerations of Head in Ice Hockey. Int. J. Biomed. Sci. Eng. 2019, 7(2), 26-32. doi: 10.11648/j.ijbse.20190702.11

Copy | Download

AMA Style

Hesam Sarvghad Moghaddam, Whitman Kwok. Role of Helmet Fit on Angular and Linear Accelerations of Head in Ice Hockey. Int J Biomed Sci Eng. 2019;7(2):26-32. doi: 10.11648/j.ijbse.20190702.11

Copy | Download

@article{10.11648/j.ijbse.20190702.11,
  author = {Hesam Sarvghad Moghaddam and Whitman Kwok},
  title = {Role of Helmet Fit on Angular and Linear Accelerations of Head in Ice Hockey},
  journal = {International Journal of Biomedical Science and Engineering},
  volume = {7},
  number = {2},
  pages = {26-32},
  doi = {10.11648/j.ijbse.20190702.11},
  url = {https://doi.org/10.11648/j.ijbse.20190702.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijbse.20190702.11},
  abstract = {Increasing the protection efficiency of helmets is counted as the biggest challenge in ice hockey. The main objective of this study is twofold: first to understand the effect of fitting on the protection capability of ice hockey helmets, and second to determine a possible optimal fit with respect to minimum head accelerations. A purpose-built monorail drop tower was utilized to perform front and front boss impacts at a velocity of 4.47m/s on a custom headform outfitted with a commercial helmet (CCM Resistance) with no gap (tight fit), 2mm (regular fit), and 5 mm gaps (loose fit). It was observed that while in both impacts linear accelerations were lower for the regular fit model, the loose fit model predicted the lowest angular accelerations. A loosely-fitted helmet provides non-deterministic shifting upon impact which generally leads to a wider standard deviation of linear and angular accelerations. The results indicated that in front impacts while introducing a gap reduced the risk of focal injuries, only the loose fit model suggested lower risks of concussive injuries. However, the regular and loose fit models showed better protection against focal and concussive injuries in the front boss impacts, respectively.},
 year = {2019}
}

Copy | Download

TY  - JOUR
T1  - Role of Helmet Fit on Angular and Linear Accelerations of Head in Ice Hockey
AU  - Hesam Sarvghad Moghaddam
AU  - Whitman Kwok
Y1  - 2019/09/06
PY  - 2019
N1  - https://doi.org/10.11648/j.ijbse.20190702.11
DO  - 10.11648/j.ijbse.20190702.11
T2  - International Journal of Biomedical Science and Engineering
JF  - International Journal of Biomedical Science and Engineering
JO  - International Journal of Biomedical Science and Engineering
SP  - 26
EP  - 32
PB  - Science Publishing Group
SN  - 2376-7235
UR  - https://doi.org/10.11648/j.ijbse.20190702.11
AB  - Increasing the protection efficiency of helmets is counted as the biggest challenge in ice hockey. The main objective of this study is twofold: first to understand the effect of fitting on the protection capability of ice hockey helmets, and second to determine a possible optimal fit with respect to minimum head accelerations. A purpose-built monorail drop tower was utilized to perform front and front boss impacts at a velocity of 4.47m/s on a custom headform outfitted with a commercial helmet (CCM Resistance) with no gap (tight fit), 2mm (regular fit), and 5 mm gaps (loose fit). It was observed that while in both impacts linear accelerations were lower for the regular fit model, the loose fit model predicted the lowest angular accelerations. A loosely-fitted helmet provides non-deterministic shifting upon impact which generally leads to a wider standard deviation of linear and angular accelerations. The results indicated that in front impacts while introducing a gap reduced the risk of focal injuries, only the loose fit model suggested lower risks of concussive injuries. However, the regular and loose fit models showed better protection against focal and concussive injuries in the front boss impacts, respectively.
VL  - 7
IS  - 2
ER  -

Copy | Download

Author Information

Hesam Sarvghad Moghaddam

Mechanical Engineering Department, Northern Arizona University, Flagstaff, USA
Whitman Kwok

ZAM Worx, Foster City, USA

Download PDF

Sections

Plain Text BibTeX RIS

APA Style

Hesam Sarvghad Moghaddam, Whitman Kwok. (2019). Role of Helmet Fit on Angular and Linear Accelerations of Head in Ice Hockey. International Journal of Biomedical Science and Engineering, 7(2), 26-32. https://doi.org/10.11648/j.ijbse.20190702.11

Copy | Download

ACS Style

Hesam Sarvghad Moghaddam; Whitman Kwok. Role of Helmet Fit on Angular and Linear Accelerations of Head in Ice Hockey. Int. J. Biomed. Sci. Eng. 2019, 7(2), 26-32. doi: 10.11648/j.ijbse.20190702.11

Copy | Download

AMA Style

Hesam Sarvghad Moghaddam, Whitman Kwok. Role of Helmet Fit on Angular and Linear Accelerations of Head in Ice Hockey. Int J Biomed Sci Eng. 2019;7(2):26-32. doi: 10.11648/j.ijbse.20190702.11

Copy | Download

@article{10.11648/j.ijbse.20190702.11,
  author = {Hesam Sarvghad Moghaddam and Whitman Kwok},
  title = {Role of Helmet Fit on Angular and Linear Accelerations of Head in Ice Hockey},
  journal = {International Journal of Biomedical Science and Engineering},
  volume = {7},
  number = {2},
  pages = {26-32},
  doi = {10.11648/j.ijbse.20190702.11},
  url = {https://doi.org/10.11648/j.ijbse.20190702.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijbse.20190702.11},
  abstract = {Increasing the protection efficiency of helmets is counted as the biggest challenge in ice hockey. The main objective of this study is twofold: first to understand the effect of fitting on the protection capability of ice hockey helmets, and second to determine a possible optimal fit with respect to minimum head accelerations. A purpose-built monorail drop tower was utilized to perform front and front boss impacts at a velocity of 4.47m/s on a custom headform outfitted with a commercial helmet (CCM Resistance) with no gap (tight fit), 2mm (regular fit), and 5 mm gaps (loose fit). It was observed that while in both impacts linear accelerations were lower for the regular fit model, the loose fit model predicted the lowest angular accelerations. A loosely-fitted helmet provides non-deterministic shifting upon impact which generally leads to a wider standard deviation of linear and angular accelerations. The results indicated that in front impacts while introducing a gap reduced the risk of focal injuries, only the loose fit model suggested lower risks of concussive injuries. However, the regular and loose fit models showed better protection against focal and concussive injuries in the front boss impacts, respectively.},
 year = {2019}
}

Copy | Download

TY  - JOUR
T1  - Role of Helmet Fit on Angular and Linear Accelerations of Head in Ice Hockey
AU  - Hesam Sarvghad Moghaddam
AU  - Whitman Kwok
Y1  - 2019/09/06
PY  - 2019
N1  - https://doi.org/10.11648/j.ijbse.20190702.11
DO  - 10.11648/j.ijbse.20190702.11
T2  - International Journal of Biomedical Science and Engineering
JF  - International Journal of Biomedical Science and Engineering
JO  - International Journal of Biomedical Science and Engineering
SP  - 26
EP  - 32
PB  - Science Publishing Group
SN  - 2376-7235
UR  - https://doi.org/10.11648/j.ijbse.20190702.11
AB  - Increasing the protection efficiency of helmets is counted as the biggest challenge in ice hockey. The main objective of this study is twofold: first to understand the effect of fitting on the protection capability of ice hockey helmets, and second to determine a possible optimal fit with respect to minimum head accelerations. A purpose-built monorail drop tower was utilized to perform front and front boss impacts at a velocity of 4.47m/s on a custom headform outfitted with a commercial helmet (CCM Resistance) with no gap (tight fit), 2mm (regular fit), and 5 mm gaps (loose fit). It was observed that while in both impacts linear accelerations were lower for the regular fit model, the loose fit model predicted the lowest angular accelerations. A loosely-fitted helmet provides non-deterministic shifting upon impact which generally leads to a wider standard deviation of linear and angular accelerations. The results indicated that in front impacts while introducing a gap reduced the risk of focal injuries, only the loose fit model suggested lower risks of concussive injuries. However, the regular and loose fit models showed better protection against focal and concussive injuries in the front boss impacts, respectively.
VL  - 7
IS  - 2
ER  -

Copy | Download