Research On The Construction And Practice Of The Technical Evaluation System Of Clean And Jerk Of The Lightweight And Excellent Male Weightlifters In China

Objective:Based on the on-the-spot collection of the technical parameters of clean an d jerk of Chinese male lightweight athletes and the statistical study of large sa mple size,this paper tries to establish a comprehensive evaluation model of cl ean and jerk technique of Chinese male lightweight weightlifters.This paper an alyzes the commonness and individual differences among the various links of t he clean and jerk technique of elite athletes,finds the best breakthrough to im prove the clean and jerk performance,and grasps the clean and jerk technique of Chinese male lightweight weightlifters comprehensively and continuously,s o as to provide a theoretical basis for the late training of athletes and the culti vation of new forces,and an important basis for the formulation of coaches' tr aining plan.Methods:The subjects of this study are 47 Chinese lightweight athletes who have p articipated in the 2019 National Men's Weightlifting Championships,2019 Asian Weightlifting Championships,2020 Tokyo Olympic Games qualification compet ition and 2019 World Weightlifting Championships.The author used three-dimensional fixed focus camera measurement and Simi three-dimensional movement analysis method to obtain the movement parameters of 96 athletes' successful l unge clean and jerk technique.A relevant index model of clean and jerk techn iques is established by using grey correlation analysis method,Pareto analysis method and factor analysis method.Thus,a comprehensive evaluation and analy zing of techniques of some excellent athletes is achieved.Result:1.According to the relevant research on weightlifting,78 kinematic indexe s of clean and jerk technology were selected;the weight of kinematic indexes of clean and jerk technology was selected by using grey correlation and Pareto analysis method,and 55 indexes with high correlation were obtained.It includ es 28 kinematic indexes from lifting bell to chest stage and 27 kinematic inde xes from upper rising force stage;finally,40 kinematic effective indexes are d etermined by factor analysis method,19 kinematic indexes from lifting bell to chest stage and 21 kinematic indexes from upper rising force stage.2.According to the principal component analysis,we classify and name th e biomechanical factors of the two stages of the clean and jerk technique.The contribution rates of each factor are as follows: A.lifting the bell to the ches t stage: the second force factor(13.974%)> the force attitude factor(13.536%)> the bell receiving factor(10.551%)> the lifting the bell attitude factor(9.778%)> the force stability factor(8.402%)> the first force factor(7.9)85%)> longitudinal movement factor of barbell(7.656%)> force generating effect factor(7.410%);B.upper force generating stage: longitudinal movement factor of barbell(13.441%)> force generating factor(12.307%)> squatting rhythm f actor(10.137%);braking attitude factor(9.752%);receiving factor(9.327%);ba rbell falling rhythm factor(8.630%);force generating effect factor(7.879%);su pporting stability Fixed factor(7.712%).3.The paper constructs the technical characteristics and the hierarchical m odel of the lifter's bell to chest stage and upper power stage,which helps to establish the scoring system the clean and jerk techniques of Chinses elite lightw eight male weightlifters.4.According to the established comprehensive scoring system for the tech nical indexes of clean and jerk of China's elite lightweight male weightlifters,t his paper provides a comprehensive analysis on the clean and jerk techniques of Chen Lijun,the creator of 69 kg world record,and Tang Jian,the creator of81 kg world record.In the stage of lifting the barbell to the chest: the main deficiency of Che n Lijun is that the distance between the two centers of the human bar is too l arge in the front and back directions,which results in the increase of resistanc e arm,which increases the difficulty of lifting the barbell;the falling speed of the barbell is faster,which increases the difficulty of receiving the barbell.Tang Jian's deficiency is mainly manifested in the following aspects: the s mall change of knee joint angle at the knee extension stage is not conducive t o the subsequent power generation;the speed of the barbell on the Z axis is n ot enough;the height of the barbell at the power generation stage is small,inc reasing the difficulty of receiving the barbell.In the rising stage: the main deficiency of Chen Lijun is that the knee joi nt angle of two legs is too small when receiving the bell.Tang Jian's deficien cy is mainly manifested in the increase of weight of barbell,the unsatisfactory height of rising,the unreasonable rhythm and the slow vertical upward speed of barbell in the driving link,the small knee joint angle and the unstable supp ort of barbell.Conclusion:1.The quantitative evaluation of the technical index of clean and jerk of Chinese lightweight elite male weightlifters can directly reveal the relationship among the specific indexes in the principal component index of clean and jerk of lightweight athletes.combined with the individual technical style of athletes in training practice,some technical deficiencies of athletes can be evaluated comprehensively.2.The evaluation index system established in this study has a good application prospect in the evaluation of clean and jerk technique of athletes,and can provide reference for coaches and athletes to carry out targeted training and create good results.