WHY KIAI?

• RELEASE TENSION
• INCREASE POWER
• BUILD UP CONFIDENCE
• INTIMIDATION OF OPPONENT

When you see people doing forms, participate in competitions, or break blocks of concrete or wood with their hands, they are always vocally expressive in what they are about to do. What names do this "shouting" have and why is it done in techniques?

The shouting, called kiai, has multiple purported purposes. ..

1. The forced and trained rapid exhalation of breath. This can be used as both focus (by focusing on breath, one is less inclined to focus on the fear of failure when faced with the thought of breaking something apparently hard), and as a method of rapidly exhaling carbon-dioxide from the body to increase oxygenated blood flow to the extremities.
   
   
2. The external (outer or omote) harmonizing of ki energy (気合 - kiai), as opposed to the internal (inner or ura) harmonization of ki energy (合気 - aiki).
   
   
3. The expulsion of intent. Kiai acts as a declaration of your fighting spirit, your internal desire to prevail in those circumstances. This can be for intimidation, self-reassurance, rallying (the war cry was essentially a form of kiai), etc.
   

Something that many people may never learn: the kiai need not always be loud. In some arts, the kiai is taught as a voiceless projection, called kage no kiai.

In addition, some arts offer specific forms of kiai, for example (from the Bujinkan:

• ei! - A growling shout, meant to accompany an attack; intended to force the opponent to lower his guard momentarily.
  
  
• toh! - A heavy shout, meant to accompany a counter; intended to make the opponent believe he has left an opening.
  
  
• ya! - A boisterous shout, meant to respond to a series of blows; intended to dishearten the opponent, making him believe that you believe you're already victorious (may tie in to folk beliefs that a battle is decided the moment two adversaries first see each other).

It's said the kage no kiai taught in the Bujinkan is a harmony of these three shouts, voiceless or in a low hum, assuring the warrior of victory. This might be viewed as a form of self-assurance, helping to maintain a form of inner calm or mushin.

During kata performance one or all of the forms of kiai may (and usually should) be performed. It plays a major part in helping to put one’s self into the proper state of mind and drive 100% of your energy/effort into your motions.

In modern day tournament competition it also can be a great advantage in fully communicating the spirit of your kata as well as the focused intent delivered through your strikes in sparring competition.