The Biomechanics Research Of College Elite Long Jumpers Take-off Technology

In this paper,we use a telemetry flesh report tester,a constant speed DV video camera,two high speed cameras, a 3D measuring forces sets and a synchronous signal emitter to test the take-off movement of the four outstanding long jump athletes.By the use of literature, expert interview, image analysis, mathematical statistics and other research methods, combined with sports anatomy, exercise physiology, sports training as well as sports biomechanics of multi-disciplinary knowledge,it can objectively reflect the technology in favor of the Long Jump kinematics, and the parameters and the optimum range of the physical and mechanics aspects,helping finding out the inner links and laws between the technical movements,such as analyzing the EMG change of some muscle or muscle group in different stages or different muscles at the same stage.It provides the reference for Chinese athletes of long jump take-off technology of the optimal combination, especially for broad-jump teaching and grassroots training.Research result:(Ⅰ)Kinematics aspects 1)The touchdown phase--The average of the research parametenhorizontal speed:8.55m/s,landing angle 54.75°,knee joint 158.61°.2)The buffer phase--Maximum buffer,The average angle of the research obect right knee joint is 139.16°,the right hip joint 143.00°and the right ankie joint 116.30°.Among the research obects,Li's right knee and hip joint angle are the smallest.In this phase,the average buffer time is 0.070s,and Li's the smallest:0.064s.3)The pedal and stretch phase--The instantaneous speed of Level 1 athlete Li taking off from ground is 9.19m/s,round angle 63°,prancing angle19.80°,the knee joint 166.68°and the hip joint 187.60°.The instantaneous speed of other Level 2 athlete taking off from ground is 8.64m/s,ground angle 66.33°prancing angle 19.93°,knee joint 161.60°and the hip joint 166.89°.The data of level 1 athlete is more reasonable than other.(Ⅱ)Muscle excitability 1)Touchdown buffer stage--The excited degree of right gastrocemius is higher,dischaige is stronger,the integral power value has reached up to 91.25uvs.The discharge strength of the right lower limb muscles and trunk muscles is bigger than that of the left lower limb muscles and upper limb muscles,but the difference is not significant.Gravity lowest moment is when most of the largest buffer muscles are showing the characteristics that the integral muscle power value tends to in or close to zero line.2)The pedal and stretch phase--The IEMG value of the trunk rectus is the largest:131.00uvs,followed by the right shares rectus:59.00uvs.(Ⅲ)The mechanics aspect 1)The touchdown phase--The average value of the maximum impact to the ground in the vertical direction is 7035.16N,and the maximum of the level 2 athletes is evidently large than that of level 1 athletes.The average horizontal force is 2820.31N,and the difference betweem different levels of atheletes is not obvious.2)The buffer phase--When it is maximum buffer,the average stress in vertical direction is 2351.86N,and the horizontal 1311.37N.The stress of level 2 athlete is larger than that of level l,but it is opposite relationship in the horizontal direction.3)The pedal and stretch phase--When they are under the biggest force in the vertical direction,the average force in the vertical is 3226.32N,int the horizontal is 562.72N.The force of level 1 athlete is larger than that of level 2,but it is opposite relationship in the horizontal direction.In this research,all the athletes are professional athletes.They have obtained many years of professional training and attended many provincial track and field competition.Their skilled technical,standard action and the coordination and economic muscle action,so the test results can reveal the basic law of the long jump take-off technology.