Analysis Of Take-off Factors Affecting The Flight Distance Of Chinese Men’s Ski Jumpers

Objective: In this research,by testing the kinematics and dynamics of the National Men ’s Ski Team team in the field and in the laboratory,Study the main factors that affect the flight distance of Chinese male ski jumpers,aiming to provide a theoretical basis for the national male ski jump team members to improve their skills and training level.Methods: 8 national men’s ski jumping teams,set up high-speed cameras on the field jumping coach tower to collect the kinematic data and flight distance of athletes in the field,Use a force plate and a camera in the laboratory to collect the dynamics and kinematics of athletes’ squat jump,countermovement jump,drop jump,and simulated jump data.The kinematics data during the take-off phase and laboratory tests were analyzed using kinovea 0.8.27,and the kinetic data were obtained using Bioware 5.1.0.0 software.The data were processed using Graphpad Prism and SPSS24.0.Statistical methods used the Generalized Estimation Equation(GEE)model to analyze the field take-off kinematic factors that affected the flight distance.Univariate variance analysis was used to analyze the differences in limb angles of athletes at domestic and abroad at specific moments;paired sample T test was used to analyze the joint angle differences between domestic and foreign athletes.;Pearson correlation analysis was used to study the maximum vertical force,CMJ jump height,SJ jump height,centrifugation Correlation between utilization rate(EUR),peak power,response force index(RSI)and flight distance.The test level is bilateral α = 0.05,and P<0.05 is considered statistically significant.Results:(1)The angle between the trunk and the assisted slide,the angle between the lower leg and the assisted slide,hip angle,and knee angle are all factors that influence the flight distance(P<0.05);(2)Hip joints during the take-off phase Peak angular velocity and knee joint angular velocity are influential factors of flight distance(P<0.05);(3)knee angle and hip joint angle are influential factors of flight distance at the end of take-off(P<0.05);(4)The knee valgus index at the lowest point of IJ was positively correlated with the flight distance(r = 0.73),and the minimum value of knee valgus at DJ was positively correlated with the flight distance(r = 0.71);(5)The peak ground reaction force during the CMJ take-off phase is positively related to the flight distance(r = 0.71);(6)centrifugal utilization There is no significant correlation with the flight distance;(7)The peak power and average power of the SJ and CMJ take-off phases are positively related to the flight distance;(8)There is a positive correlation between the CMJ extension impulse and flight distance(r = 0.75);(9)The calf and slide assist(53.54 ± 3.14 °)of the outstanding start of foreign athletes is significantly lower than that of Chinese athletes(57.62 ± 4.62 °);(10)The angle between the lower leg and the assist slide(58.22 ± 2.13 °)of the outstanding foreign athletes at the moment of introduction is significantly smaller than that of our athletes(65.59 ± 3.84 °);and the angle between the thigh and the assist slide(73.28 ± 6.15 °)is significantly larger than that of Chinese athletes 58.77 ± 3.16 °);(11)The hip joint angle(175.23 ± 1.96 °)of the outstanding foreign athletes at the end of the take-off phase was significantly greater than that of our athletes(156.37 ± 13.13 °).Conclusion:(1)Appropriately reducing the center of gravity of the body at the beginning of the take-off,increasing the extension of the limbs at the moment of launch and the end of the take-off is conducive to increasing the flight distance;(2)Properly increasing the angular velocity of the knee joint and reducing the angular velocity of the hip joint are conducive to increasing the flying distance,avoiding the torso standing upright during the stretching and stretching process;(3)Avoid excessive knee valgus during simulated jump and field jump training;(4)Increasing the explosive force of the lower limbs of Chinese athletes is conducive to improving athletic performance.