Koshi: The Center of Power Transmission by Dan Smith, Kyoshi
Koshi is the Japanese word that describes the pelvic girdle region of the human body. This region contains the lower stomach, hips and low back. All physical movement is enhanced by the efficient use of this region. This is due to the connectivity of the large muscle groups of the upper and lower body to the pelvic girdle.
The initial movement of any Shorin Ryu Seibukan movement should begin with the tightening of the shitabara or the lower stomach. The shitabara is the lower stomach muscles that are located below the navel and above the pubic bone. This area is also referred to as the tanden or center point by some Japanese martial arts. The shitabara or tanden is the center of movement of the human body. The critical role that the shitabara plays is the connection of the upper and lower large muscle groups. The shitabara leads these muscles groups to move together thus insuring the movement of the body as a whole rather than separate muscle groups moving without coordination.
The contractions of the large muscle groups that begin in the shitabara engage the koshi creating the power of Shorin Ryu Seibukan.
The storage of energy occurs in the koshi as the shitabara contracts. The large muscle groups when contracted in the proper sequence bring the energy of the contractions to the koshi. Due to the relaxed nature of the tanden the contracted muscles are enabled to remain tense while the tanden or center point remains relaxed. The relaxation of the center point is the key to natural fluid movement while the large muscle groups are being contracted. Without this natural relaxation point the human body would move like a robot.
The transfer of energy occurs from the koshi out through the large muscle groups to the small or refined muscles. The limbs of the body become the extension of the contraction that has occurred in the large muscle groups. The shitabara contracts at the beginning of a movement, relaxes in the middle and contracts again at the end which creates the whip like effect or explosive movements of Shorin Ryu Seibukan.
In summary the koshi, tanden and shitabara create movement from the center of the body. By moving the center of the body first we create the possibility of chinkuchi occurring.