The concept of KI is one of the most difficult associated with the philosophy and practice of karate. It is hardly surprising that many karateka are interested in understanding just what KI is supposed to be. Etymologically, the word "KI" derives from the Chinese "chi." In Chinese philosophy, chi was originally supposed to be that which differentiated living and non-living things. But as Chinese philosophy developed, the concept of chi took on a wider and wider range of meanings and applications. On some views, chi was held to be the most basic "stuff" out of which all things were made. The differences between things depended not on some things having chi and others not, but rather on a principle (li, Japanese = RI) which determined how the chi was organized and functioned (the view here bears some similarity to the ancient Greek matter-form metaphysic).

Modern karateka are less concerned with the historiography of the concept of KI than with the question of whether or not the term "KI" denotes anything real, and, if so, just what it does denote. There have been some attempts to demonstrate the objective existence of KI as a kind of "energy" or "stuff" that flows within the body (especially along certain channels, called "meridians"). So far, however, there have been no reputable studied published in peer-reviewed scientific journals that substantiate such claims. This does not, of course, settle the question decisively against the existence of KI, but, just yet, the evidence does not support existence claims for KI.

Not all karateka believe that KI is a kind of "stuff" or "energy." For some karateka, KI is an expedient concept -- a blanket-concept which covers intentions, momentum, will, and attention. If one eschews the view that KI is a stuff that can literally be extended, to extend KI is to adopt a physically and psychologically positive bearing. This maximizes the efficiency and adaptability of one's movement, resulting in stronger technique and a feeling of affirmation both of oneself and one's partner.

Irrespective of whether one chooses to take a realist or an anti-realist stance with respect to the objective existence of KI, there can be little doubt that there is more to karate than the mere physical manipulation of another person's body. karate requires a sensitivity to such diverse variables as timing, momentum, balance, the speed and power of an attack, and especially to the psychological state of one's partner (or of an attacker).

In addition, to the extent that karate is not a system for gaining physical control over others, but rather a vehicle for self-improvement (or even enlightenment, there can be little doubt that cultivation of a positive physical and psychological bearing is an important part of karate. Again, one may or may not wish to describe the cultivation of this positive bearing in terms of KI.

Kime (Focus)

Focus refers to the concentration of all the energy of the body in the instant a particular technique makes contact with its target. This concentration of energy is derived from the tension and relaxation of certain muscles at the correct time in conjunction with the exhalation of air from the lungs as the technique is completed. Kime will not be released if the tension of the completed technique lasts for any measurable length of time, as Kime is manifested by the speed of the technique involved. Karate movements convert power into speed, thus the fist when punching gradually accelerates and hits its target at maximum speed. If all the muscles are tensed or focused at this instant all the body's strength will be transformed from speed to power as Kime is achieved.

Everyone can kick or punch with speed and apparent power, simply by using the weight of the body or leg as it is thrown forward. This type of strength is the sort that all possess, and which is used in everyday situations, differing from person to person according to their physique. However, the strength incorporated in all Karate techniques is derived from muscle tension and relaxation, and does not, therefore, rely on body weight or size. Anyone, large or small, has the possibility of phenomenal power, once they learn to use their body correctly.

Used correctly, it is possible to reach a point at which the body will be producing maximum output in the execution of any technique. This is not to be confused with what a person thinks is the maximum output which is far below the theoretical limit.

Suppleness is important in order to achieve maximum extension and contraction of all the muscle groups as various moves are performed. The greater the distance that a contracting muscle moves as it pulls upon a limb, the greater the speed and, therefore, power of the technique. Co-ordination is vital if energy created at one point is to be transferred to, and combined with, the energy created at another.

In order to explain Kime one can compare latent energy of the body with that of sunlight. By the use of a lens the light emitted can be concentrated into a single point; the light becomes capable of burning paper, wood or even metal. Before or after this point, however, the light has very little power.