The Motion Analysis Of The Waltz Dance Double Left Rotation

Objective:Standard dance is updated with the times,athletes in order to better attract the eyes of the referee and audience,will add a large number of rotating movements in their own combination.Waltz double left rotation is one of the left turn series derived from the left turn,and it is also a common technical action in the combination of competitive routine and grade.The purpose of this study is to analyze the double left rotation of waltz dance by kinematics test methods and means,so as to explore the technical action characteristics of sports dance players at different levels to complete the dance step under the condition of double partners.In order to sum up the differences in the process,provide basic theoretical support for the teaching of sports dance.Methods:In this study,eight-lens high-speed infrared motion capture system(motion analysis,200 hz)was used to test the waltz double-left rotation movement of 12 sports dancers(6 males and 6 females)and obtain the kinematic index data such as the angle changes of the left and right hips,knees and ankle joints,the duration of each action stage,and the vertical displacement of the center of gravity in each action stage.Each pair of subjects were asked to follow the same music to complete the action.After sorting out and summarizing the index data by Excel,SPSS 20.0 was used for independent sample T test,and Excel was used to draw the curve,so as to compare the technical performance of the two groups of subjects.Results:(1)In the stage of storage,swing and supporting rotation,the excellent group of men spend less time than the control group of men;In the stretch support stage,the end stage and the total time,the excellent group of men with longer than the control group of men.In the stage of energy storage,the time of excellent group was longer than that of control group.In the stage of stretching support,follow-up,end and total time,the time of excellent group was shorter than that of control group.(2)There was a significant difference in the body center of gravity between the excellent group and the control group in the stretching support stage and the supporting rotation stage(P<0.01),and there was a significant difference in the swing stage(P<0.05).There was a very significant difference in the body center of gravity between the excellent group and the control group at the stage of energy storage,the stage of stretch support and the stage of follow-up(P<0.01).(3)The hip extension,inward and outward extension of the excellent group were greater than those of the control group.(4)The extension and internal and external rotation of the knee joint in the excellent group were greater than those in the control group.(5)The ankle plantar flexion and dorsal flexion of the excellent group were greater than those of the control group.Conclusions:(1)Men should elongate the value in the extension support stage,accelerate in the swing stage and the support rotation stage,and control the descent speed in the end stage;the woman should elongate the value in the storage stage and accelerate in the next four action stages with the help of power.(2)The men’s center of gravity should rise and guide the female partner in the stage of pedal extension support,the women’s center of gravity should keep rising into the following movement,and the women’s center of gravity should continue to rise in the following stage.(3)When preparing for the position,both men and women should pay attention to the presentation of the reflexive position to expand the range of motion of the subsequent action.The female power leg should extend far and rotate internally,and the left hip should be abduction to guide the rotation.In the stage of storage,men mainly twist the hip joint,increase the rotation of knee joint and ankle joint in the stage of pedal extension support to help complete the movement rotation,the main legs of men in the early stage of the end need to wait for the female partner,and then lead the female partner to rotate with themselves.(4)The driving force of the hip joint in the excellent group is stronger,which shows the men’s hip strap in the movement,and completes the inner and outer circle relationship between the dance partners even more well.The control group had too much curvature hip,weak hip ability,and insufficient per tic ality of the body.(5)Excellent group of knee rotation power is stronger,can support and drive the body smooth completion of rotation.The flexibility and control ability of the ankle joint in the excellent group was stronger than that in the control group,and the overall fluctuation of the movement in the excellent group was more obvious.Men in the control group did not have enough power to push their feet.