Kiai [気合]

The characters/ideograms mean, “Scream; yell; fighting spirit.” The first character means, “spirit; mind; air; atmosphere; mood,” the second character means, “fit; join.”

Used in martial arts as a means to bring about a meeting of both the internal and external energies generated through the proper application of fundamental principles of martial systems thus creating an instantaneous power transfer from the weapon, i.e. hand, foot, etc., into a target. Often assumed to be a shout or war cry but the cry is just a external manifestation that assists the practitioner with an audible cue that all the proper principles are finally applied in that one instance. 

It is used at certain points within kata practice but tends to be arbitrary since kata is about learning bunkai that will be assimilated or not assimilated as necessary to each individual and not actually a fighting scenario that is pre-ordained with specifics especially since a true combative situation is more fluid and chaotic with no set tactics, etc. 

Kiai is more of a method to create what some call an application of chinkuchi, i.e., an Okinawan dialect term about applying principles of power in karate. In the yin-yang concept as derived from ancient studies by Okinawan practitioners whereby the yin or internal along with yang or external energies are combined, coalesced and projected through principles into a power applied technique. This is something that should be applied with every technique applied regardless of any arbitrary rule that kiai must be placed at any specific point in kata, drills or kumite. 

Kiai is done without sound and it is also done with sound. In ancient times, much like the Marine’s OhRahhh shout is about instilling a fighting spirit while sending a clear signal to an adversary that a force of nature is coming and it cannot be stopped. There are times when the cry is necessary for psychological reasons and there are times when kiai is applied with no sound, but a strong exhale. 

In kiai, as with many aspects of a martial art, breathing (a fundamental principle) is critical to achieve true kiai as it is with the concept of chinkuchi. Kiai is not just a shout or war cry but a system that assists a practitioner to achieve great power, etc., in martial training. 

“No kiai (shout). Chibana Sensei explained that in the old days, karate training was done in secret, so silence was necessary. He continued that “ki" means spiritual or internal energy and "ai" means to meet. Kiai, then is the precise moment (meeting) when the internal and external energy is brought together. Kiai is synonymous with kime. Kiai can be done with no sound, but with a strong exhale. Kiai and kime then is the instant when the neurological and physical response become one.” ~ Nakata, Pat Sensei