Aerobics Do Scissors Leap 1/2 Turn On The Perspective Of Kinematics Analysis

This paper gains kinematics parameter data of cut-mode & body-changing jumpof swivel 180° movement of some Jilin Province outstanding body-building exercisesathletes by applying the method of three dimensional phantom survey. On the base ofthese parameter data, it researches the techniques of these athletes' cut-mode &body-changing jump of swivel 180° movement using the biological mechanicsmethod. It discovers the main factors of affecting the techniques of cut-mode &body-changing jump of swivel 180° movement. Then the paper establishes correcttechnical concepts and movement structures of cut-mode & body-changing jump ofswivel 180° movement;it makes it clear on the movement theory's connotation. Bydoing this it aims to makes up the insufficiency brought by human's sensation andachieves the goal of technical diagnosis. Furthermore, it can enhance the overall levelof body-building exercises' repertoire athletics and promote the scientificdevelopment of body-building exercises' movement training. Besides, it can alsoprovide theory basis of instructing modern training practice. This thesis draws theconclusions below through analysis:First, all athletes' speed of center of gravity level reduce gradually in the processof taking off. Afterwards, the center of gravity their bodies' vertical velocity starts toincrease fast. Its increasing scope averages about 2.05m/s;the knee joint biggestcushion time angle averages about 142.75°±4.41. And this angle is good for extendingthe pedal of taking-off leg.Second, from the vision of cushion time, it is slightly higher than the long-jumpathletes' taking-off leg cushion time. However, it is similar with high-jumpers'cushion time. Compared with high-jumpers and the long-jumpers' taking-off time, thetotal time is slightly longer. And this does not favor the athletes' take-off legs toproduce the advantageous pedal. Therefore, under the premise of full-movementcushion, the athletes should reduce the taking-off time.Third, at the taking-off time of extending pedal, both the knee joint and coxaextend fully. This process of fast extending pedal can increase the pedal strength andenhance vertical velocity which the body's center of gravity leaps. Because of straightleg swinging of cut-mode & body-changing jump, the athletes' leg-swinging coxaangular speed is much lower than high jumper' movement.Fourth, in the time of stage-soaring, the athletes' overall center of gravity'sincreasing scope is not very big. It mainly has two reasons from the analysis of thisarticle. The first one is that in the stage of taking-off, the pedal angle is slightly big(average for 83.1°±3.7). And it leads to the insufficiency of altitude. The second is,the movement of cut-mode & body-changing jump requests the taking-off leg kneestraightly pendulum. This will length the radius of swinging and the rotation inertiabecomes bigger. So it take the trouble to bend the hip and enlarge the swingingdifficulty of taking-off legs. Thus it affects the altitude and becomes the immediatecause of airborne posture.Fifth, after cut-mode & body-changing jumping athletes' body gravity centerreaches its highest lever in the soar stage, the biggest soaring-angle appears duringthis process. It means that the highest lever of gravity center and the biggestsoaring-angle do not appear at the same time.Sixth,in the soaring-stage, soon after each athlete taking off for a short time, theshoulder and the hip's angle of torsion speed appear an obvious peak almost at thesame time. The reason is that after taking off , swinging-leg upwards and swingsinside rapidly. This reverse is not only the peak of angular speed, but also the peak ofreversing scope. Thus when athletes do the movement of cut-mode & body-changingjump, swinging-leg must be rapid and powerful after taking-off. And this relates to thesuccess or failure of this movement.Seventh,looking from the test result, from the first stage's ground-leaving timeof taking-off leg to the last stage's ground-reaching cushion time, the shoulder and thehip's angle of torsion speed averages respectively 191.8°±17.3 and 197.8°±26.5. Andathletes basically realizes the swivel 180°.