Repetitive Head Impacts: A Major Concern At All Levels of Sports

Question of balance

Finding a way to reconcile two competing demands – minimizing contact in practice in order to reduce the number of concussions sustained and the number of hits players sustain over the course of a week and a season that emerging science, now more than ever, suggests may have a deleterious cumulative effect on a player’s cognitive function over the long term, while at the same time maximizing the amount of time in practice learning how to tackle and block without head-to-head contact – time that is needed to maximize the protective effect of proper tackling on the number of head-to-head hits players sustain in game action, which can not only result in concussion, but catastrophic neck and spine injuries – is challenging, but clearly not impossible.

“As a scientist, I am not in a position to make policy,” Broglio told MomsTEAM, but “we can’t just reduce [the number of contact practices] without looking at the whole picture. We don’t know if 18% means anything, or how much less [in terms of the number of impacts] is meaningful.”

If he were making policy, however, Broglio would “lean more towards the cautious side” in limiting contact practices, which is not to say that he doesn’t think “that a football program could be successful” with some limits on full-speed contact practices.  Pointing to rugby, where players practice tackling without helmets without increased risk of head injury in games, he “didn’t necessarily buy” the argument advanced by some experts that limiting contact practices would expose football players to increased injury risk in games.

As Broglio writes in his 2013 study, however, his view comes with a very important caveat: only if “extra emphasis on the appropriate tackling technique [is] put in place to ensure that the highest level of safety was maintained during games.”

While the widespread adoption of limits on full-contact practices in football is intended to make the game safer, some experts agree with Broglio that caution should be the byword.  A March 2013 review of current risk-reduction strategies in the British Journal of Sports Medicine (11) reminds state high school athletic associations and legislatures that, in enacting rules, such as limits on full-contact practices, they “need to carefully consider potential injury ‘trade-offs’ associated with the implementation of injury-prevention strategies, because every change may have certain advantages and disadvantages. That is, by reducing one risk or danger, additional risks may be created.” In other words, as the Michigan study points out, limits on full-contact practices could create additional risk of injury to players because they haven’t spent enough time learning to tackle properly.

The results of at least two recent studies, however, suggest that reductions in full-contact practices can be accompished safely without putting players at additional risk, while researchers continue looking for the head trauma “holy grail”: a threshold – whether it is number of hits per week, over the course of the season, of a certain force, or to a certain part of the helmet  (e.g. facemask, top of the head) above which players are at an unacceptably high risk of permanent brain injury.

A 2013 study by researchers at Wake Forest Baptist Hospital and Virginia Tech (24) showed that reducing the number of head hits in practice did not, as some had predicted (25) lead to higher force impacts during games.

More recently, a 2015 study (39) reported that comprehensive coach education in teaching “heads up” tackling, combined with practice contact restrictions, such as implemented by Pop Warner, can be effective in reducing the rate of concussions in youth football.

The challenge is to determine whether a critical number of head hits exists above which this type of brain injury appears, and then to get players and coaches to agree to limit play when an athlete approached that number.

As the recent Purdue studies demonstrate, science is coming closer than ever before to determining that number,

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1. Talavage T, Nauman E, Breedlove E, et. al. Functionally-Detected Cognitive Impairment in High School Football Players Without Clinically-Diagnosed Concussion. J Neurotrauma. 2010; DOI: 10.1089/neu.2010.1512.

2.  Crisco JJ, Fiore R, Beckwith JG, et al. Frequency and location of head impact exposures in individual collegiate football players. J. Athl Train 2010;45:549-559.

3. Field M, Collins MW, Lovell MR, Maroon J. Does age play a role in recovery from sports related concussion? A comparison of high school and collegiate athletes. J Pediatr. 2003;414:546-553.

4. Pullela R, Raber J, Pfankuch T. et al. Traumatic injury to the immature brain results in progressive neuronal loss, hyperactivity and delayed cognitive impairments. Dev Neurosci 2006;28:396-409.

5. Stern R, Riley D, Daneshvar D, Nowinski C, Cantu R, McKee A. Long-term Consequences of Repetitive Brain Trauma: Chronic Traumatic Encephalopathy. Phys. Med. & Rehab. 2011;3;S460-S467. DOI:10.1016/j.pmrj.2011.08.008.

6. Greenwald R, Chu J, Beckwith J, Crisco J. A Proposed Method to Reduce Underreporting of Brain Injury in Sports. Clin J Sport Med2012; 22(2):83-85.

7. Echlin P, Tator C, et al. A prospective study of physician-observed concussions during junior ice hockey: implications for incidence rates.  Neurosurg Focus 2010;29(5):E4.

8. Bazarian JJ, Zhu T, Blyth B, Borrino A, Zhong J.  Subject-specific changes in brain white matter in diffusion tensor imaging after sports-related concussion.  Magnetic Resources Imaging. 2012; 30(2): 171-180.

9. March N, Bazarian JJ, Puvenna V, Janigro M, Ghosh C, et. al. Consequences of Repeated Blood-Brain Barrier Disruption in Football Players. PLoS ONE 2013;8(3): e56805. doi: 10.1371/journal.pone.0056805.

10.  Broglio SP, Martini D, Kasper L, Eckner JT, Kutcher JS.  Estimation of Head Impact Exposure in High School Football: Implications for Regulating Contact Practices.  Am J Sports Med 2013;20(10). DOI:10.1177/036354651302458 (epub September 3, 2013).

11. Benson B, McIntosh A, Maddocks D, et. al. What are the most effective risk-reduction strategies in sport concussion? Br J Sports Med 2013;47:321-326.

12. Breedlove EL, Robinson M, Talavage TM, et al. Biomechanical correlates of symptomatic and asymptomatic neurophysiological impairment in high school football. J Biomech. 2012;45(7):1265-1272.

13. Talavage TM, Nauman EA, Breedlove EL, et al. Functionally-detected cognitive impairment in high school football players without clinically diagnosed concussion. J Neurotrauma. 2014;31(4):327-338. doi:10.1089/neu.2010.512.

14. McKee AC, Stein TD, Nowinski CJ, et al. The spectrum of disease in chronic traumatic encephalopathy. Brain. 2013;136(Pt 1):43-64.

15.  David Epstein. The Damage Done: While Concussive Hits Dominate the Debate, A Groundbreaking New Study Suggests That Minor Blows – And There Can Be Hundreds Each Game – Are Just As Traumatic. Sports Illustrated. November 1, 2010 (accessed October 14, 2013 at http://sportsillustrated.cnn.com/vault/article/magazine/MAG1176377/2/).

16. McAllister TW, Ford JC, Flashman LA, et al. Effect of head impacts on diffusivity measures in a cohort of collegiate contact sport athletes.  Neurology 2013; doi:10.1212/01.wnl.000438220.16190.

17. Savica R, Parisi JE, Wold LE, Josephs KA, Ahlskog JE. High School Football and Risk of Neurodegeneration: A Community-Based Study. Mayo Clin Proc 2012;87(14):335-340.

18. Jordan BD, et al. Head trauma and participation in contact sports as risk factors for Alzheimer’s disease. Neurology 1990;40:347.

19. McAllister TW, Flashman LA, Maerlender A, Greenwald RM, Beckwith JG, et al. Cognitive effects of one season of head impacts in a cohort of collegiate contact sports athletes.  Neurology 2012;78:1777-1784.

20. Bazarian JJ, Zhu T, Zhong J, Janigro D, Rozen E, Roberts A, Javien H, Merchant-Borna K, Abar B, Blackman EG. Persistent, Long-term Cerebral White Matter Changes after Sports-Related Repetitive Head Impacts. PLoS ONE. 2014;9(4): e94734 DOI: 10.1371/journal.pone.0094734

21. Koerte IK, Ertl-Wagner B, Reiser M, Zafonte R, Shenton ME. White matter integrity in the brains of professional soccer players, without a symptomatic concussion. JAMA. 2012;308:1859-1861.

22. Koerte IK, E Hartl, Bouix S, Pasternak O, Kubicki M, Rausher A, Li D, et al. A prospective study of physician-observed concussion during a varsity university hockey season: white matter integrity in ice hockey players.  Part 3 of 4. Neurosurgical Focus. 2012;33:E3.

23.  Bazarian JJ, Zhu T, Zhong J, et al. Persistent, Long-term Cerebral White Matter Changes after Sports-Related Repetitive Head Impacts. PLOS ONE. 2014;9(4):e94734.

24. Cobb BR, Urban JE, Davenport EM, Rowson S, Duma SM, Maldjian JA, Whitlow CT, Powers AK, Stizel JD. Head Impact Exposure in Youth Football: Elementary School Ages 9-12 Years and the Effect of Practice Structure. Ann Biomed Eng. ( 2013): DOI: 10.1007/s10439-013-0867-6 (online ahead of print)

25. Kontos P, Fazio V, Burkart S, Swindell H, Marron J, Collins M. Incidence of Sport-Related Concussion among Youth Football Players Aged 8-12 Years. J Pediatrics 2013. DOI 10.1016/j.jpeds.2013.04.011

26. Davenport EM, Whitlow CT, Urban JE, et. al. Abnormal White Matter Integrity Related To Head Impact Exposure in a Season of High School Varsity Football.  J Neurotrauma 2014;31:1617-1624.

27.  High School Football Players Show Brain Changes after One Season. Radiological Society of America. December 1, 2014. (accessed at http://www2.rsna.org/timssnet/media/pressreleases/14_pr_target.cfm?id=781)

28. Bahrami N, Davenport E, Whitlow CT, et. al. Head Impacts and White Matter Changes in High School Football: A TBSS Analysis. (research paper). Radiological Society of America. December 1, 2014.

29. Reynolds BB, Patrie J, Henry EJ, Goodkin HP, Broshek DK, Wintermark M, Druzgal TJ.  Practice type effects on head impact in collegiate football. J Neurosurg. Published online August 4, 2015; DOI:10.3171/2015.5.JNS15573.

30. ‘Deviant brain metabolism’ found in high school football players. Purdue University News. August 19, 2015. (accessed at http://www.purdue.edu/newsroom/releases/2015/Q3/deviant-brain-metabolism-found-in-high-school-football-players.html)

31. Breedlove KM, Breedlove EL, Robinson M, Poole VN, King JR, Rosenberger P, Nauman EA. Detecting neurocognitive & neurophysiological changes as a result of subconcussive blows in high school football athletes.  Ath. Tr. & Sports Health Care. 2014;6(3):119-127.

32.Poole VN, Breedlove EL, Shenk TE, Abbas K, Robinson ME, Leverenz LJ, Nauman EA, Dydek U, Talavage TM.  Sub-concussive HIt Characteristics Predict Deviant Brain Metabolism in Football Athletes. Developmental Neuropsychology 2015;40(1):12-17, DOI:10.1080/87565641.2014.984810.

33. Nauman EA, Breedlove KM, Breedlove EL, Talavage TM, Robinson ME, Leverenz LJ. Post-Season Neurophysiological Deficits Assessed By ImPACT and fMRI in Athletes Competing in American Football.  Developmental Neuropsychology. 2015;40(2):85-91. doi:10.1080/87565641.2015.1016161.

34. Robinson ME, Shenk TE, Breedlove EL, Leverenz LJ, Nauman EA, Talavage TM.  The Role of Location of Subconcussive Head Impacts in fMRI Brain Activation Change. Developmental Neuropsychology 2015;40(2): 74-79. doi:10.1080/87565641.2015.101224.

35. Shenk TE, Robinson ME, Svaldi DO, Abbas K, Breedlove KM, Leverenz LJ, Nauman EA, Talavage TM. fMRI of Visual Working Memory in High School Football Players.  Developmental Neuropsychology 2015;40(2):63-68. doi:10.1080/87565641.2015.1014088.

36. Svaldi DO, Joshi C, Robinson ME, Shenk TE, Abbas K, Nauman EA, Leverenz LJ, Talavage TM. Cerebrovascular Reactivity Alterations in Asymptomatic High School Football Players.  Developmental Neuropsychology 2015;40(2):80-84. doi:10.1080/87565641.2014.973959.

37. Abbas K, Shenk TE, Poole VN, Robinson ME, Leverenz LJ, Nauman EA, Talavage TM. Effects of Repetitive Sub-Concussive Brain Injury on the Functional Connectivity of Default Mode Network in High School Football Athletes. Developmental Neuropsychology 2015;40(1):51-56. doi:10.1080/875665641.2014.990455.

38. Chun IY, Mao X, Breedlove EL, Leverenz LJ, Nauman EA, Talavage TM. Detection of Longitudinal WM Abnormalities Due to Accumulated Head Impacts. Developmental Neuropsychology 2015;40(2):92-97. doi: 10.1080/87566541/2015.1020945. .

39. Kerr ZY, Yeargin S, McLeod TC, Nittoli VC, Mensch J, Dodge T, Hayden R, Dompier TP. Comprehensive Coach Education and Practice Contact Restriction Guidelines Result in Lower Injury Rates in Youth American Football.  Orthopaedic J Sports Med. 2015;3(7). doi:10.1177/2325967115594578.

40. Stamm JM, Bourlas AP, Baugh CM, et al. Age of first exposure to football and later-life cognitive impairment in former NFL players.Neurology 2015 Jan 28 [Epub ahead of print]

41. Asplund CA, Best TM. Brain damage in American Football Inevitable consequence or avoidable risk? Br J Sports Med 2015;49:1015-1016. 

42. National Federation of State High School Associations. Recommendations and Guidelines for Minimizing Head Impact Exposure and Concussion Risk in Football. Report from the July 2014 NFHS Concussion Summit Task Force. (accessed at http://www.nfhs.org/articles/concussion-task-force-recommendations-to-be-implemented-in-2015/)

43. Mihalik JP, Bell DR, Marshall SW, Guskiewicz KM. Measurement of head impacts in collegiate football players: an investigation of positional and event-type differences. Neurosurgery 2007; 61:1229-1235.

44. Trulock S, Oliaro S. Practice contact. Safety in College Football Summit. Presented January 22, 2014, Atlanta, GA.

45. Crison JJ et al. Frequency and location of head impact exposures in individual collegiate football players. J Athl Tr. 2010; 45:549-559

46. Broglio SP, Williams RM, O’Connor KL, Goldstick J. Football Players’ Head Impact Exposure After Limiting of Full-Contact Practices. J Ath Tr. 2016;51(7):000 (e-published ahead of print July 2016).

Originally posted April 6, 2012; most recently updated August 23, 2016