The Study On Technical Characteristics Of Body-bent Backward Somersault With2Twists In Elite Trampoline Athletes

The scientists mainly focused on the problems to be solved in trampoline trainingsince China developed the trampoline16years before. While the research on thetechnical features of trampoline action is lagging relatively. Although trampoline hasleaped into the front ranks of the world,it is still difficult to describe accurately thetechnical features of different actions.The paper selected piked somersault two circle movements (811<、813<、831<)of four elite men trampoline athletes as the investigated subject，and studied it by theintegrated methods of literature, image analysis, mathematical statistics and expertinterviews. The study divided one complete trampoline action into sevenstages:pressing the net,hauling stage, posture formative stage,holding the position andoverturning,body-showing,falling after body-showing and preparation of touching thenet. The results showed that:(1)In the stage of pressing the net,each technical characteristic has no greatdifference.In hauling stage,813<and831<action is similar technical characteristics.The height from the net and gravity of leaving the net,screen angle and verticalvelocity leaving the net is greater than the other two movements in811<actionmoment.(2) In the formative stages of posture，when twist angle of the first circle is thesame,the more the twist angle of the second circle,the shorter the formation of pikeposition, and the flip angle is smaller,but it has little impact on the flip angularvelocity.In the stage of holding the posture and overturning,when the swivel degree inthe second circle somersault is the same,the characteristicsare the similar in the stage.The height of the gravity is changed with the time.When the time of the stage is closerto the midpoint of the total time, the center of gravity height variation is smaller. Flipangle and angular velocity is related with the distribution of the swivel structure.(3) The hip flexion angle and the hip angle in the end of distant action is littledifferent in body-showing stage. But the hip angle is the same when the body-showing stage is end.The body-showing angular velocity is different with theswivel action. Somersault angular velocity is small when the body-showing action isin the highest point of the body.In the two circle pike somersault action, the differenttwist angle in hip flexion moment is nearing completed; the same action of the secondcircle somersault twist action, the angular velocity tends to be the same.(4) In the preparation of touching the net stage, The technical characteristics ofthe three actions are similar,indicating that the action index are tends to be the same inthe stage ofpiked somersault two circle movements...