Kokyu-ryoku [呼吸力]

The characters/ideograms mean "breathing force; abdominal breath power; breath power." The first character means, "call; call out to; invite," the second character means, "suck; imbibe; inhale; sip," the third character means, "power; strength; strong; strain; bear up; exert." 

This term is derived from Kokyurikigaku [呼吸力学] meaning, "mechanics of respiration." The first character means, "call; call out to; invite," the second character means, "suck; imbibe; inhale; sip," the third character means, "power; strength; strong; strain; bear up; exert," the fourth character means, "study; learning; science. 

As martial artists working diligently toward mastery of the underlying fundamental principles of martial systems we learn proper breathing techniques. As novices, and until we get proficiency in those breathing methods, we tend toward muscular strength to get things done. This is considered normal but where the rubber meets the road is the knowledge that this is a transitory stage toward proper application of principles and therefore techniques, etc. 

In order to transcend the need for muscular strength in applying martial technique we have to learn and apply kokyu-ryoku. To achieve proficiency in kokyu-ryoku you use that initial muscular strength to develop "abdominal breath/breathing power." Kokyu-ryoku is the key to achieving many other principles that promote use of breath to achieve or rather provide the foundation on which many principles work. Your application of principles and techniques then begin to become "effortless." 

If I had to choose a fundamental principle that applies to all the fundamental principles of martial systems it would be breathing or kokyu-ryoku. The practice of this is all part and parcel to the understanding of kokyurikigaku or mechanics of respiration. 

Highlights: 

- a direct result of physical training.

- stronger than muscular strength.

- the path to effortless techniques (i.e. adhering to fundamental principles of martial systems/effectiveness)

- leads to the power inherent in "ki." 

Bibliography:

Perlman, Steven J. "The Book of Martial Power: The Universal Guide to the Combative Arts." New York. The Overlook Press. 2006.

Alexander, David. "The Four Levels of Aikido Training." CFA, Vol.2 No.25 (Issue #48).