The Comparative Analysis Of Run-up Jump Techniques In Jump Serves, Back Row Spikes And Front Row Spikes Of The Volleyball Games From The Perspective Of Kinematics

This thesis focuses on the research of run-up jump techniques in technical movements such as jump serves, back row spikes and front row spikes. The research takes second grade male volleyball players majoring in Sports Training at the College of Physical Education, Soochow University as experimental subjects and studies the run-up jump techniques in technical movements such as jump serves, back row spikes and front row spikes from the three-dimensional perspective of Kinematics by various methods including documentary data research, videotape analysis, mathematical and physical statistics study and comparative analysis. Analyses of their technical movements help a lot in our recognizing the technical and theoretical shortcomings of the three techniques which are prevalent among volleyball players, thus providing reserve volleyball talents with valuable referential data and facilitating future textbook compiling. Conclusions are as follows:1. The eight experimental subjects all adopted the approach of two-step run-up and level step jump in their run-up jumps for the three techniques, with their step length increasing together with their steps. They all followed the rule of"small size for the first step and big for the second". The fact that the run-up distance for the jump serve is shorter than that of the back row spike and front row spike is mainly because the step length of the jump serve is not longer than that of the back row and front row spikes when it comes to the second step of the run-up.2. In terms of the run-up speed of the eight experimental subjects in the process of the three techniques, the speed of the back row spike ranks the first and that of the jump serve ranks the last. More time is needed for the run-up of the jump serve than that of the back row spike and the front row spike. The speed of the jump serve in terms of the first step is obviously less than that of the other two techniques and it is also true of the general speed on the condition of the same run-up distance.3. The change of the angles of the coax and knee of the eight subjects all met the technical and mechanical requirements of the techniques of spikes. When the angle of the knee changes, the angle of the left knee joint becomes larger, which is in line with the research of the predecessors and amongst which the angle changes to the greatest extent in the case of the jump serve.4. There is no absolute correlation between the increase of the speed and the size of the steps. In accordance with the conclusion of Xing Honglin, the size of the step only constitutes one possible rather than absolute reason for the increase of the speed.5. The conversion ratio for the horizontal velocity in the case of the jump serve is higher than that in the case of the back row spike and the front row spike. However, considering the liftoff vertical velocity, the vertical velocity for the jump serve in time of feet liftoff is far less than that of the front row spike. Therefore, in judging the jump effect, one must not only take into consideration the horizontal velocity but also the gravity center vertical speed at the very moment of feet takeoff.6. The major differences of the three techniques in terms of the jump time lies in the pedal-and-stretch phase, in that in the process of the jump serve, the left foot and the right foot don't synchronize with each other in lifting off, namely the pedal-and-stretch phase. The taking-off and touching-down distances in the case of the back row spike and the jump serve all exceed those in the case of front row spikes, which demonstrates that farther forward-dashing jump-distance exists in both back row spikes and jump serve.7. It took more time for the eight experimental subjects to buffer than to pedal and stretch in the jumping process of the three movements, with much converted energy and a great jumping height. But the time consumed in buffering and pedaling varied little in jumping, which shows that they fall behind of excellent athletes to some extent.8. Players in the research can use corresponding jump techniques according to different jump purposes. Front row spikes feature large takeoff angles. Jump serves and back row spikes demand not only height but a certain level speed to realize Z dash jump, so the level speed at the time of jumping exceeds the same index in the technique of front row spikes, whereas the vertical speed varies a great deal in jump serves, back row spikes and front row spikes.