Concussions

[Sanko]

Bruising, including bruising of the brain, i.e. concussion, is common
in martial art training. It is part of the risk and often an
inevitable part of practicing a contact / combat sport. Concussion
could occur accidentally, for instance you running into your
opponent's technique or slipping and hitting your head on the floor.
Sometimes it is not accidental and either you did not guard / block
properly or your opponent purposed to knocked you out, which may or
may not be legal in your system. Either way, it comes with the
territory. Sparring in the martial arts are often about hitting and
getting hit. The main idea is to hit your opponent without being hit
yourself. Often easier said than done, but that, after all, is what
training is about.

Read more about concussions and concussion symptoms at my blog:
http://sooshimkwan.blogspot.com/2011/07/concussions.html