Kiai or "Shout":

Kiai is a Japanese term that is a compound of "ki" meaning mind, will, or spirit and "ai" being the contraction of the verb awasu, signifying "to unite". It is a short yell that some martial artists shout before or during a fight or technique. In bujutsu, it is usually linked to the inner amassing of energy released in a single explosive focus of will. A kiai can also refer to this mental focus of a martial artist.

• a psychological effect on your enemy.
• a psychological effect on yourself, so-called "amping yourself up".
• to provide an escape route for exhalation of air.
• to keep air pressure in your body balanced (holding your breath while taking impact from a kick, punch or the ground can cause injury).
• to rapidly contract the transverse abdominal and other core muscles to provide support for striking techniques and protection to the internal organs.

Students of martial arts such as karate, taekwondo or Judo (or related arts such as taiko drumming) use kiai to focus energy when executing a technique. It also refers to the shout that accompanies some kata.

There are many legends surrounding using kiai in novel ways. Some use it as a secret offensive technique that involves using your voice to create huge amounts of sound waves. In another legend a samurai froze a pack of wolves in their tracks by simply glaring at them.