Biomechanical Analysis Of Pelvic Movement In Yang Style Taijiquan "Louxiaobu" Stance

For decades past,the practice of taijiquan as a sport for competition, entertainment,physical conditioning,art and combat has been spreading all over the world.It is an important branch of Chinese traditional martial arts(Wushu),and because it can be practiced for many different purposes,it suits contemporary society's interests.Taijiquan is a well-known sport,but its practice,because of cultural differences, has been focused only on the movements,neglecting the understanding of the theory of the martial art.Concepts that are difficult to understand,such as "掤(peng)","虚实(xushi)","缠丝劲(chansijin)",also translated as "ward-off","empty-full" and "spiral energy" respectively,can only be understood by those who immerse themselves in the Chinese culture and in the practice of the art.The concept from taijiquan's theory that this research emphasizes is "旋腰转脊,旋腰转胯(xuan yao zhuan ji,xuan yao zhuan kua)",translated as "rotate the waist turn the spine,rotate the waist turn the hip".The pelvis is what connects the waist,spine and hip,and during the taijiquan movement they move accordingly to its rotational progression.The main purpose of this research was to use scientific mathematical methods and language to explain taijiquan movement and stance.For the biomechanical analysis of the pelvic movement in Yang style taijiquan louxiaobu stance,both movement(captured by a motion capture system) and the force applied to the ground (captured by force platforms) by the subjects were analyzed.In taijiquan,the pelvic movement is mainly based on rotation.It has a wide range of rotation in the vertical and frontal axes,while in the sagittal axis the range of rotation is small.When the body is moving forward,its doesn't move in a straight line,but it moves forward in a rotational progression.If the rotation in one direction is small,then the rotation in the other directions is wide.This way the movement can be more fluent keeping its rotational characteristic.To keep the body in "中正 (zhongzheng)" posture,the pelvic movement's amplitude in the sagittal axis is small. During the taijiquan gait,when the body moves backwards and when the heel touches the ground,because at the vertical axis the pelvic movement's amplitude is wide,the frontal axis rotation is in the direction of pelvic retroversion.When there is pelvic retroversion the spine becomes as a straight line and can better act as the body's vertical axis of rotation.At the double stance phase,from the point when the heel touches the ground until the body moves into "弓步(gongbu)" stance,the range of the pelvic movement in all three axes of rotation is wide.This is a manifestation of"掤(peng)".