Research Of Biomechanics Characteristics Of Plyometric Training To Lower Limb Explosive Of Sprinters

Sprint is always a weak competition to our country.Since Liu Xiang won medal in the Olympies, we rarely get a good performance. With Lightning Bole broke the limits of human agam and again, our country scholars discuss the factors restricting sprint performance and (?) to improve the performance in a wide range. The effect starts to get results, Zhang Peimeng and Su Bingtian broke the national record and get the performance in the international competition.The research will study the explosive training methods---Plyometric Training (PT) through biomechanical testing and research, hoping to provide a theoretical exercise training support. The generally used training methods of PT are CMJ (countermovement jump) and DJ (drop jump).The research will study the countermovement jump with different knee angle and drop jump with different drop height, in order to choose a better training method. Six male high-level athletes(20.5±2.1) of Dalian University of Technology were selected as research subjects, using DLUT4060piezoelectric multi-component force platforms and three dimensional infrared image capture system to collect kinematics and kinetic data.1、Though biomechanics and statistical analysis,the joint work of countermovement is different with different knee angle. Among the90°,120°and150°of knee angle, hip work of90’is the largest comparing with120°and150°,120°and150°is basically the same; knee work of90°is the largest,120°is larger than150°; angle work of120°is the largest,90°is large than150°.The hip work and knee work of90°is significant different with120°and150°,no significant different between120°and150°.The ankle work of90°is significant different with120°and150°, and significant different between120°and150°2、Though biomechanics and statistical analysis,the peak GRF(ground reaction force)、 vertical displacement and stiffness of drop jump is different, which is drop from the height of40cm、60cm and80cm.80cm of peak ground reaction force is the largest,60cm is larger than40cm; the vertical displacement of80cm is the largest,60cm is larger than40cm; stiffness of60cm is the largest,40cm is larger than80cm. The peak GRF of40cm is significant different with80cm, and no significant different with60cm; the vertical displacement of40cm is significant different with80cm,and no significant different with60cm; no significant different of stiffness among40cm,60cm and80cm.According to the training objective of different choosing different training method,90°of countermovement is suitable for knee and hip extensors,120°of countermovement is suitable for ankle flexors. To the height of drop jump,60cm is the recommended height, if above this height concerning peak GRF,injury risks will increase.