Analysis Of Motion Characteristics In Landing Stage Of Chinese Elite Male Skiers In Freestyle Skiing Aerials

Objective: In the study of freestyle skiing aerials,there is less analysis of kinematic characteristics of athletes in the landing stage.The landing quality directly influences the performance of the sport.In this paper,we focused on freestyle skiing aerial skills on landing stage and analysed the characteristics of the speed of center gravity and angles of each joint in one-circle and two-circle action,such as bL,bF,bLF,bLT,bFF and other types of action.The ultimate goal of this paper is to provide scientific reference for athletes’ special training.Method: The method is mainly experimental testing,using three Japanese CASIO high-speed cameras(sampling frequency 300HZ)to simultaneously shoot and collect the one-circle or two-circle training action videos(all successful actions)of 7 elite men’s freestyle skiing aerials athletes,using SIMI-motion analysis system to do 3D video analysis,building models of the human body and make the definition that athletes’ center of gravity is decided by the total weight of athletes and that of ski wear’s,and finally obtains the kinematic parameters of the center of gravity and all joints.Result: When the center of gravity is in the left and right direction,the speed bL is 1.36±0.52 m/s,and the bF is 3.03±0.85 m/s;When the center of gravity is in vertical direction,the speed bL is 8.68±1.12 m/s,which is less than bF 9.65±1.52 m/s;knee angle bL is 157.69±14.01 degrees,and bF is 156.11±15.02 degrees;the hip angle bL is 131.95±7.78 degrees,and bF is 137.95±7.33 degrees;the shoulder angle b F is 117.4±18.64 degrees,95.58±18.32 degrees.When the center of gravity of two-circle action bLL,bLF,bLT and bFF is in the left and right direction,the speed is 3.56±1.16m/s,2.38±0.36 m/s,3.43±0.77 m/s and 3.94±0.38 m/s.When the center of gravity is in the vertical direction,the speed is 10.85±1.42 m/s,12.06±1.75 m/s,11.26±1.29 m/s and 12.73±2.52 m/s.Conclusion: 1.The speed of the center of gravity varies as the type ofaction and the height of the platform changes.The rotational movement affects the change of speed of the center of gravity.In the one-circle movement,The speed of the center of gravity of one-circle movement is9.92 m/s,and the speed of the center of gravity of twist action is 10.11m/s;In the two-circle movement,the speed of the center of gravity of bLL is 11.88 m/s,bLF is 12.17 m/s,bLT is 12.78 m/s,bFF is 13.37 m/s.2.At the landing stage,the joint angle of the lower limb is controlled within a certain range and does not change with the type of action;the angle of ankle varies less under different types and heights.3.In the landing stage,the joint angle of the upper limb is affected by the rotation movement,and the lateral drift of the take-off and the air movements affect the joint angle of the upper limb.4.In China,there are obvious kinematics characteristics of excellent men’s successful athletic performance including strong stability and skillful movement technique when landing.