If you have ever seen a martial arts movie, or watched a class training in the dojo, have you wondered why the students yell? The sounds a martial artist makes when executing a punch or kick is not really ‘yelling’, it is a controlled breathing technique to focus power and demonstrate ‘spirit’. In Shotokan karate we are taught to relax our muscles until the moment of impact. It is at that moment that the air deep in our lungs is expelled and a one syllable sound such as HI, or EIE is made.
Just doing this breathing technique stirs the adrenalin and increases power as all the muscles contract at that moment of impact. Usually the kiai is used when landing a decisive blow, performing kata (at two points in the kata,) when beginning a drill then when turning from one direction to the other and when making a strike or counterattack while sparring.