Fencing response

The fencing response is an unnatural position of the arms following a concussion. Immediately after moderate forces have been applied to the brainstem, the forearms are held flexed or extended (typically into the air) for a period lasting up to several seconds after the impact. The fencing response is often observed during athletic competition involving contact, such as combat sports, American football, hockey, rugby union, rugby league and Australian rules football. It is used as an overt indicator of injury force magnitude and midbrain localization to aid in injury identification and classification for events including on-field and/or bystander observations of sports-related head injuries.[1]

Relationship to fencing reflex and posturing

The fencing response designation arises from the similarity to the asymmetrical tonic neck reflex in infants. Like the reflex, a positive fencing response resembles the en garde position that initiates a fencing bout, with the extension of one arm and the flexion of the other.

Tonic posturing (see abnormal posturing) preceding convulsion has been observed in sports injuries at the moment of impact[2][3] where extension and flexion of opposite arms occur despite body position or gravity. The fencing response emerges from the separation of tonic posturing from convulsion and refines the tonic posturing phase as an immediate forearm motor response to indicate injury force magnitude and location.


The neuromotor manifestation of the fencing response resembles reflexes initiated by vestibular stimuli. Vestibular stimuli activate primitive reflexes in human infants, such as the asymmetric tonic neck reflex, Moro reflex, and parachute reflex, which are likely mediated by vestibular nuclei in the brainstem. The lateral vestibular nucleus (LVN; Deiter’s nucleus) has descending efferent fibers in the vestibulocochlear nerve distributed to the motor nuclei of the anterior column and exerts an excitatory influence on ipsilateral limb extensor motor neurons while suppressing flexor motor neurons. The anatomical location of the LVN, adjacent to the cerebellar peduncles (see cerebellum), suggests that mechanical forces to the head may stretch the cerebellar peduncles and activate the LVN. LVN activity would manifest as limb extensor activation and flexor inhibition, defined as a fencing response, while flexion of the contralateral limb is likely mediated by crossed inhibition necessary for pattern generation.[citation needed]

In simpler terms, the shock of the trauma manually activates the nerves that control the muscle groups responsible for raising the arm. These muscle groups are activated by stimuli in infants for instincts such as grabbing for their mothers or breaking their falls. The LVN has neurons that connect it to motor neurons inside grey matter in the spinal cord, and sends signals to one side of the body that activate motor neurons that cause extension, while suppressing motor neurons that cause flexing. The LVN is located near the connection between the brain and the brain stem, which suggests that excessive force to the head may stretch this connection and thus activate the LVN. The neurons that are stimulated suppress neighboring neurons, which prevents neurons on the other side of the body from being stimulated.

Injury severity and sports applications

In a survey of documented head injuries followed by unconsciousness, most of which involved sporting activities, two thirds of head impacts demonstrated a fencing response,[4] indicating a high incidence of fencing in head injuries leading to unconsciousness, and those pertaining to athletic behavior. Likewise, animal models of diffuse brain injury have illustrated a fencing response upon injury at moderate but not mild levels of severity as well as a correlation between fencing, blood brain barrier disruption, and nuclear shrinkage within the LVN,[4] all of which indicates diagnostic utility of the response.

The most challenging aspect to managing sport-related concussion (mild traumatic brain injury, TBI) is recognizing the injury.[5] Consensus conferences have worked toward objective criteria to identify mild TBI in the context of severe TBI.[5][6][7][8][9] However, few tools are available for distinguishing mild TBI from moderate TBI. As a result, greater emphasis has regularly been placed on the management of concussions in athletes than on the immediate identification and treatment of such an injury.[5][6]

On-field predictors of injury severity can define return-to-play guidelines and urgency of care, but past criteria have either lacked sufficient incidence for effective utility,[10][11] did not directly address the severity of the injury,[12] or have become cumbersome and fraught with inter-rater reliability issues.[13] By providing a clear, discernible physiological event immediately upon injury, the fencing response can discern moderate brain injury forces from milder forces, providing an additional criterion by which the identification and classification of concussions can be improved, with immediate application to sport-related on-field diagnoses and decisions affecting return-to-play status for athletes, thereby facilitating the transition from diagnosis to the treatment of any post-concussion symptoms (PCS).[citation needed]

Further application

The fencing response may also have the potential to indicate traumatic brain injury for soldiers in military settings, specifically with regard to blast injury.[citation needed] There are currently no studies or data to determine the utility of the fencing response in such an arena.

Notable fencing displays

Increased awareness of clinical significance on behalf of the bystander is critical to the utility of the fencing response designation.[14] Therefore, notable fencing displays are listed below in order to aid the bystander in identifying the various physical manifestations of the fencing response as well as demonstrating the prevalence of such a response in popular sporting and social events.


  1. ^ Newton, Phil (August 28, 2009). "Youtube helps identify a new tool in the evaluation of brain injury". Psychology Today. Retrieved April 4, 2015.
  2. ^ McCrory, P. R.; Berkovic, S. F. (11 April 2000). "Video analysis of acute motor and convulsive manifestations in sport-related concussion". Neurology. 54 (7): 1488–1491. doi:10.1212/wnl.54.7.1488. PMID 10751264. S2CID 43197411.
  3. ^ McCrory, P. R; Bladin, P. F; Berkovic, S. F (18 January 1997). "Retrospective study of concussive convulsions in elite Australian rules and rugby league footballers: phenomenology, aetiology, and outcome". BMJ. 314 (7075): 171–174. doi:10.1136/bmj.314.7075.171. PMC 2125700. PMID 9022428.
  4. ^ a b Hosseini, Ario H.; Lifshitz, Jonathan (September 2009). "Brain Injury Forces of Moderate Magnitude Elicit the Fencing Response". Medicine & Science in Sports & Exercise. 41 (9): 1687–1697. doi:10.1249/MSS.0b013e31819fcd1b. PMID 19657303.
  5. ^ a b c Guskiewicz, Kevin M.; Bruce, Scott L.; Cantu, Robert C.; Ferrara, Michael S.; Kelly, James P.; McCrea, Michael; Putukian, Margot; Valovich McLeod, Tamara C. (2004). "National Athletic Trainers' Association Position Statement: Management of Sport-Related Concussion". Journal of Athletic Training. 39 (3): 280–297. PMC 522153. PMID 15514697.
  6. ^ a b "Concussion (Mild Traumatic Brain Injury) and the Team Physician". Medicine & Science in Sports & Exercise. 38 (2): 395–399. February 2006. doi:10.1249/01.mss.0000202025.48774.31. PMID 16531912.
  7. ^ Aubry, Mark; Cantu, Robert; Dvorak, Jiri; Graf-Baumann, Toni; Johnston, Karen; Kelly, James; Lovell, Mark; McCrory, Paul; Meeuwisse, Willem; Schamasch, Patrick; Concussion in Sport (CIS) Group (2002). "Summary and Agreement Statement of the 1st International Symposium on Concussion in Sport, Vienna 2001". Clinical Journal of Sport Medicine. 12 (1): 6–11. doi:10.1097/00042752-200201000-00005. PMID 11854582.
  8. ^ Cantu, Robert C. (October 2006). "An overview of concussion consensus statements since 2000". Neurosurgical Focus. 21 (4): E3. doi:10.3171/foc.2006.21.4.4. PMID 17112193.
  9. ^ McCrory, P; Johnston, K.; Meeuwisse, W.; Aubry, M.; Cantu, R.; Dvorak, J.; Graf-Baumann, T.; Kelly, J.; Lovell, M.; Schamasch, P. (1 August 2005). "Summary and agreement statement of the 2nd International Conference on Concussion in Sport, Prague 2004". British Journal of Sports Medicine. 39 (Supplement 1): i78–i86. doi:10.1136/bjsm.2005.018614. PMC 1725173. PMID 15793085.
  10. ^ de Kruijk, J R; Leffers, P.; Menheere, P. P. C. A.; Meerhoff, S.; Rutten, J.; Twijnstra, A. (1 December 2002). "Prediction of post-traumatic complaints after mild traumatic brain injury: early symptoms and biochemical markers". Journal of Neurology, Neurosurgery & Psychiatry. 73 (6): 727–732. doi:10.1136/jnnp.73.6.727. PMC 1757354. PMID 12438478.
  11. ^ McCrory, Paul R.; Berkovic, Samuel F. (1998). "Concussive Convulsions". Sports Medicine. 25 (2): 131–136. doi:10.2165/00007256-199825020-00005. PMID 9519401. S2CID 22738069.
  12. ^ Collins, Michael; Iverson, Grant; Lovell, Mark; McKeag, Douglas; Norwig, John; Maroon, Joseph (2003). "On-Field Predictors of Neuropsychological and Symptom Deficit Following Sports-related Concussion". Clinical Journal of Sport Medicine. 13 (4): 222–229. doi:10.1097/00042752-200307000-00005. PMID 12855924. S2CID 18035638.
  13. ^ Gill, Michelle; Windemuth, Ryan; Steele, Robert; Green, Steven M. (January 2005). "A comparison of the Glasgow Coma Scale score to simplified alternative scores for the prediction of traumatic brain injury outcomes". Annals of Emergency Medicine. 45 (1): 37–42. doi:10.1016/j.annemergmed.2004.07.429. PMID 15635308.
  14. ^ "Fencing Response Awareness". Theconcussionblog.com. 2011-09-21. Retrieved 2015-04-04.
  15. ^ "Justin McBride Concussion". YouTube.com. 2007-07-14. Archived from the original on 2021-12-21. Retrieved 2015-04-04.
  16. ^ "California RB Jahvid Best leaves game after scary fall". Sports.espn.go.com. 2009-11-08. Retrieved 2015-04-04.
  17. ^ "Jahvid Best Epic Concussion (Multiple Angles)". YouTube.com. 2009-11-07. Archived from the original on 2021-12-21. Retrieved 2015-04-04.
  18. ^ "Masvidal vs Ben Askren". Youtube.com. 2020-03-29. Retrieved 2020-08-26.[dead YouTube link]
  19. ^ "Colts' Collie taken off field on stretcher – NFL.com". Blogs.nfl.com. 2010-11-07. Retrieved 2015-04-04.
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  22. ^ "Denarius Moore leveled by DeMarcus Milliner". YouTube.com. 2010-10-23. Archived from the original on 2021-12-21. Retrieved 2015-04-04.
  23. ^ "Boise State Vs. Oregon State: James Rodgers Blindsided, Hits Ground And Stays Down". SBNation.com. 2010-09-25. Retrieved 2015-04-04.
  24. ^ "FSU's Kenny Shaw OK after being knocked unconscious". Orlandosentinel.com. Retrieved 2015-04-04.
  25. ^ "Domi KO's Ulf 95-96". YouTube.com. 2009-02-20. Archived from the original on 2021-12-21. Retrieved 2015-04-04.
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  27. ^ "James May hurt during Top Gear stunt". Telegraph.co.uk. 2010-12-23. Retrieved 2015-04-04.
  28. ^ Niall, Jake (2010-04-12). "Game has 'never been tougher'". The Age. Retrieved 2017-12-31.
  29. ^ BestGameOnEarth (2010-04-11), Jordan Lewis gets knocked out vs Western Bulldogs, archived from the original on 2021-12-21, retrieved 2017-12-31
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  31. ^ "Pique given all-clear after clash with Valdes". Reuters. 25 April 2012.
  32. ^ Bonn, Kyle (26 April 2015). "Oscar headed to hospital after thunderous clash with Ospina". ProSoccerTalk.
  33. ^ Newell, Sean (19 October 2015). "Chinese Player Knocks Out Teammate with Bicycle Kicks to the Face". Vice.
  34. ^ Davis, Callum (2017-02-04). "Marcos Alonso challenge on Hector Bellerin was '100% a foul', says Arsene Wenger". The Telegraph.
  35. ^ "Joe Flacco suffers concussion on hit from Kiko Alonso". NFL.com. 2017-10-26. Retrieved 2017-10-27.
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  38. ^ "Marlon Moraes KO's Aljamain Sterling". YouTube. December 9, 2017. Retrieved December 13, 2017.[dead YouTube link]
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  41. ^ Williams, Charean (30 September 2022). "Tua Tagovailoa leaves on a stretcher". ProFootballTalk. NBC Sports. Retrieved 30 September 2022.


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