The Kinematics Analysis Of Rumba Square Step

Purpose:This study conducted a detailed experimental study on the kinematic characteristics(displacement,speed and angle)of the body center of gravity and six major joints(left hip,right hip,left knee,right knee,left ankle and right ankle)of the rumba square step of eight excellent female Latin dancers,and collected data and made a quantitative and systematic analysis to explore the movement characteristics of the standard Rumba square step in different rhythms.Points to provide theoretical reference for evaluating sports effect,improving sports performance and scientific degree of training.Methods:APAS(Ariel performance analysis system)three-dimensional motion analysis system and motion capture system were used to analyze the athletes'technical movements.Hannafen human model was selected to analyze the related joints from three aspects:displacement,speed and angle.Statistical and mathematical analysis methods were used to fit empirical formulas to guide training.Results:(1)By the time,the center of gravity of the players in the X-axis(left and right)direction of the first 4 beat was "(?)" type distribution,the last 4 beat was "(?)"type distribution;The center of gravity was distributed in a "(?)" shape in the first 4 beats along the Y-axis(front and rear)direction with time,and in the last 4 beats in a"?"shape.The body gravity is distributed in a "?" shape along the z-axis(up anddown)direction with time.The body gravity was distributed in a "small ?"shape inthe first 4 beats and a "large ?" shape in the last 4 beats in the 3D direction with time.(2)With time,the velocity of body gravity was distributed in a "?" shape in the x axis,y axis,z axis and 3D direction,and there were 2?3 wave peaks in the 3D velocity of the 6 joints of the lower limbs.(3)The left hip angle changed little in the first 4 beats and greatly in the last 4 beats,and the overall right hip angle changed greatly in the 8 beats.The angle of the left knee changed little in the first 4 beats of time and greatly in the last 4 beats.The change rule of the right knee was opposite to that of the left knee.The angle of the left ankle changed "N" in the first 4 beats and "(?)" in the last 4 beats.The change of the right ankle was opposite to that of the left ankle.(4)Transition movements al,a2 and a8 are slower,a3,a6 and a7 are faster,a4 is slow and a5 is fast.(5)the empirical formulas of the pendulum amplitude dx and dy of the center of gravity in the X-axis and Y-axis with height(h)aredx=2.2295h-2.6316,dy=1.5729h-1.7498 respec ively.Conclusion:(1)The displacement of the players'center of gravity in the direction of three-dimensional space presents a periodic distribution,in which the displacement of the first 4 beats in the left and right directions changes less than that of the last 4 beats,and the movement amplitude shows the characteristics of the former small and the latter large,highlighting the difference in movement strength.Before and after and up and down 4 beat and 4 beat after the displacement is basically the same,action amplitude difference is not big;(2)The range of velocity change is from small to large:center of gravity<left and right hip joint<right and left knee joint<right and left ankle joint,in which the motion velocity characteristics of left and right bilateral symmetric joints of lower limbs show a typical symmetrical distribution;(3)The angles of the left and right hips,knees and ankles all showed asymmetrical distribution before and after each 8 beats,but the motion angles of the left and right sides of the lower limbs presented a typical symmetrical distribution.(4)The transition actions between each beat of the rumba square step take up different time of each bar,which makes the movements show the difference of"priority" and highlight the beauty of the steps.(5)The pendulum amplitude and height of the center of gravity at left and right and before and after were linearly distributed,and the empirical formula was fitted by unitary linear regression according to multiple groups of experimental data;The fitted barycenter displacement formula and the time proportion of each transition movement in each section can provide a reference for the standardized teaching of rumba square step and the practical training of athletes.