Breathing and ki
Most martial artists have heard of the concept of Ki. Ki refers to the natural energy of the Universe, which permeates everything (see Ki topic). Ki is not breath, it is the power that makes it breathing possible. It is the power behind movement and thought and is in the oxygen we breathe and the blood that flows through us.
Ki within the body is similar to power in a rechargeable battery. Occasionally it needs to be replenished. The Ki of the universe is inexhaustible, but the body needs fresh Ki to maintain its vitality. By energizing the body with Ki, it is revitalized naturally enabling it to fight off illness. The secret to replenishing Ki is in breathing.
Breathing through the nose enables the body to process Ki energy effectively. Most people understand the importance of breathing in through the nose, but breathing out through the nose requires a deeper understanding of the nature of Ki. Martial artists need to absorb and process Ki to generate the power and they must be able to retain Ki until it is needed. When we inhale, we bring oxygen and Ki into our body. When we exhale through the mouth, we expel carbon dioxide, but we also expel the Ki. If we continuously expel Ki, we never build a reserve of Ki within the body. However, exhaling through the nose transfers the Ki to the dan tien or hara. Each breath strengthens the dan tien. Once sufficient Ki has been stored, the Ki may be expelled with tremendous force. This is known as the Kiai where the breath is expelled through the mouth. This is the reason that there are usually only two times within each pattern where we Kiai. We have to recharge the Ki for a while before it may be released again. If we try to Kiai with every technique, we quickly become fatigued since we are expelling Ki with every breath.