Ki (or Chi) is the energy that flows through each object or living thing. It can be transported between these and is always present.
There are 3 types of Ki:
Human or Animal Ki can be split up again in:
Human Ki can be influenced by many internal (mood, spirit, food) and external (weather, someone else, something that happens) things. Many applications of Ki are known such as acupuncture, acupressure, mental healing, massage, pressure points and so forth.
The Ki circulation system covers the entire body. It supplies each organ, each muscle and even every cell of the body with energy. Ki must flow as natural and freely as possible to maintain good health. By training certain techniques of Aiki-jutsu-do, T'ai Chi Chuan, Chi Kung, and others, Ki can be bundled, be controled and even directed.
Ki generation can be accomplished internally (comes from the lower abdomen - Lower Dan Tien or Hara or Center - and is guided by the concentrated spirit Yi) and externally (muscle tension, massage, acupressure and acupunture). Yi must guide the Ki.
The waist is the source of all movement and in Aiki is referred to as the Center. It controls all movement. By regulating the breathing (breathing in when going along or preparing, breathing out when moving forward), Ki is directed to the outer channels for direct application.
The human body has two main flows of Ki (Control flow and Functional flow), 12 channels and 8 special channels. The 2 main flows run central on the front and back of the torso. When Ki is sent to these main flows it is called Small Circulation. This runs from the groin area over the front of the body to the head, and back on the rear of the torso back to the groin area. When Ki is also sent to the 12 channels it is called Big Circulation. Every Ki channels is connected to a paired pair of organs. That is why Ki training is beneficial to the organs. You can do local Ki training (Wai Dan) or total Ki or Dan Tien Ki training (Nei Dan).
Ki channels run through the entire body just like the nervous system (from top to toe). Along these channels many Ki points are allocated. All martial arts use Wai Dan exercises. Nei Dan is primarily used in the techniques and the execution thereof. If both local Ki and total Ki are used the entire technique will be much stronger and more fluent.
For those who wish to build up the Original Essence (in the kidneys) and store it in the Dan Tien (Center) it is advisable to seek a professional Chi Kung or Nei Kung teacher.
At the highest level of Chi Kung (Ki training) it is possible to launch an attack to one of the 108 Ki-points that are sensitive to this. Such an attack can have serious consequences. 72 of these points are less dangerous and are not lethal, but 36 Ki-points are vital. In essence, a martial artist should know how to undo such an attack by applying the correct counterpressure. A Ki attack can be done with a finger, fist, foot, elbow or hold. The attack deregulates blood flow and Ki flow. Many martial arts use Ki attacks, such as Kung Fu, T'ai Chi Chuan, Hsing I, Gun Tao, and of course Aiki-jutsu-do. Shaolin priests even master Iron Shirt techniques whereby an attack can be deflected merely by focusing Ki to the point of attack.
In Aiki-jutsu-do several Ki attacks are used, mostly those that are not lethal, but merely inflict pain so uke is more susceptible to the guided path of movement.