"Ki: meet, match, union. Ai: life force, vitality, spirit." Kiai: a command for the body and spirit to come together as one unit to accomplish something. That is one of the more elaborate definitions of the kiai, or fighting yell, of the martial arts. A kiai serves many purposes. Physically, it tightens the body and expels air from the lungs, focusing energy. It is also a weapon in itself. In our culture, people do not often holler at each other, so it is startling to have someone roar in your face. In a threatening situation, a well-timed kiai can be as good as a kick; if used properly, the latter may not be necessary.

Explaining the kiai to those unfamiliar with karate can be something of a challenge. Listeners tend to get a glazed look in their eyes when they hear phrases like "outward manifestation of the chi." A kiai is a powerful sound that comes from the diaphragm. It provides an extra boost of energy, usually to an accompanying strike or block, and helps the practitioner channel his or her energy.

The concept of noise as a focusing technique is not unique to the martial arts. Tennis players often growl as they hit the ball, and dancers match their breathing with their movements. Barbaric yawps and Rebel yells are found throughout history and literature. These sounds serve a duel purpose: they raise confidence and unnerve opponents. A Xena-esque war cry may not sound like a kiai, but they serve the same basic purpose.

In competition, a strong kiai is important, especially for shy students. It offers an opportunity to show others that you are serious about the martial arts. The kiai is also helpful when you need that last burst of energy-it will propel you through the form, sparring match, or board break. Beginners are often self-conscious about their kiai since they are not used to roaring in other languages, but that passes. The kiai can be one of the most devastating techniques in a martial artist's arsenal.