1993 Volume 2 Issue 1 Pages 49-60
The purposes of this study were firstly to observe relationship between positions of lower abdominal region (called "Seika-Tanden in Japanese) and whole-body centers of gravity (CGs) in five types of the correct sitting posture (called "Seiza" in Japanese) and the sitting postures crossing legs on four conditions (called "Kekkahuza" in Japanese), and secondly to compare these postures by degree of spinal curvature which had measured with a conformateur. Five types of "Seiza" was prescribed as follows: (1) Tanza: incorrected "Seiza", (2) Sokushinza: "Seiza" corrected with piling a top side in one foot on an arch of another foot, (3) Koushiza: "Seiza" corrected with crossing hallux, (4) Heishiza: "Seiza" corrected with placing toes side by side, (5) Yanagida's Seiza; "Seiza" in "Seitai-Hou". Four conditions on "Kekkahuza" were (1) non-cushion, (2) one cushion, (3) add one more cushion, (4) add two more cushions Estimation of CGs was based on H. Matsui's body segment parameters by means of pictures in profile. Positions of "Tanden" were obtained by T. Sato's drawing figure method. The subjects were eleven Judoist (on "Tanza","Sokushinza", "Koushiza" and "Heishiza"), a trained man in "Seitai-Hou" and two untrained men (on "T. Yanagida's Seiza") and a practician of "Zazen" (on "Kekkahuza"). The results were as follows; 1) As to characteristics in each posture estimated by degree of spinal curvature, "Tanza" characterized by a shape of that like an alphabet C, and the lumbar curvature was not found. On the other hand, the corrected "Seiza" ("Sokushinza", "Koushiza", "Heishiza" and "T. Yanagida's Seiza") and "Kekkahuza" expressed curvatures like an alphabet S that showed the same characteristics as a standing posture. 2) In both "Seiza" and "Kekkahuza", the positions of CGs located above the navels, and the heights of CGs were higher than those of "Tanden". 3) In "Seiza", the antero-posterior positions of CGs were more behind than those of "Tanden" (50.0%), but in the case of some subjects, those of CGs were close to of "Tanden" in "Heishiza" (47. 4%), especially for trained, both were fairly close to each other in "T. Yanagida's Seiza" (49.3%). 4) About "Kekkahuza", the antero-posterior positions of the CGs were in the rear of those of "Tanden" on all conditions (39.5-42.2%).
