Originally posted January 7, 2011 this was one of the first places to examine and educate people about the Fencing Response, since that time this post has been viewed nearly 50,000 times. This is a great resource.
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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 football, hockey, rugby, boxing and martial arts. It is used as an overt indicator of injury force magnitude and midbrain localization to aid in injury identification and classification for events including, but not limited to, on-field and/or bystander observations of sports-related head injuries.
Source: Hosseini, A. H., and J. Lifshitz. Brain Injury Forces of Moderate Magnitude Elicit the Fencing Response. Med. Sci. Sports Exerc., Vol. 41, No. 9, pp. 1687–1697, 2009.
The Concussion Blog 
What a GREAT post. This kind of information rocks. It’s important, it’s much-needed, and the video just does an amazing job of illustrating it.
Nicely done.
I have such mixed feelings about this video. Educationally, I think it is awesome in giving a true depiction of the fencing response and posturing with concussions. However, I have a strong stomach (former police officer saw my share of death/dismemberment/suicide…), anyways, I have a strong stomach, and this actually made my physically ill. I had to take a break part way through…I couldn’t handle it. I actually thought I was going to throw up. The celebrations by the boxers angered me. Thanks for posting though.
Thanks for spreading the word about our work. We too believe it is an important step in developing standards for the medical management of concussion.
Thanks for pointing out this to me. On one hand, the number of video instances you can find of this is scary. On the other hand, the most remarkable thing about this video is how many different sports are represented. Highly educational. Again, very scary.