Kinematics Analysis Of The Throwing Step And Final Force Technique Of Chinese Young Women Javelin Athletes

The throwing level of adult female javelin throwers in my country is now steadily improving,while young female javelin throwers are easily overlooked or not deeply researched due to unstable technology,short training years,and immature technical mastery.They are regarded as the future development of javelin.The reserve force needs to be given early technical theoretical support during the stage of technical growth to be optimized.Therefore,technical research on young female javelin athletes is very necessary.This article selects six young female javelin athletes in the 2020 Chinese Athletics Association Throwing Event Internal Test Competition as the research objects,mainly using the test method and the human motion image analysis software(SBCAS 2W4)to analyze the young female javelin throwing steps and final exertion techniques.Kinematics analysis of stride length,stride time,stride frequency,torso backward angle,body center of gravity height and speed,knee joint angle,speed at the moment of shot,height,angle and other indicators,and compare and analyze with the throwing technique of excellent domestic athletes,after research and analysis,the results show:(1)The young athletes’ throw steps are 1.32 m,1.55 m,1.61 m,1.53 m,which do not meet the characteristics of "one big,two big,three largest,four smallest",the last step is too long,and the step frequency slower.(2)The angle of the torso backward in the cross step exceeds the reasonable range of 4.12°,and the angle of the torso in the last step continues to decrease.The right shoulder angle of the two steps after the throwing step exceeds the reasonable range of 7.63°,5.56°,and the right elbow angle of the last step is 136.01°.(3)The height of the center of gravity in the first three steps did not change much,the height of the center of gravity in the last step decreased by 0.12 m,and the horizontal speed of the center of gravity in the four steps were 5.78m/s,5.88m/s,5.34m/s,4.60m/s,showing a decreasing trend.The R ↓-L ↓ center of gravity horizontal speed loss rate reached 13.85%,and the L ↓-gun shot instant loss rate reached 53.91%.(4)The shooting angle of young athletes is 37.33°,the shooting height is 1.76 m,and the shooting speed is 20.38m/s.(5)The degree of positive correlation between shot speed and athletic performance is the highest,followed by the L ↓ horizontal speed of the center of gravity;the cross-step trunk backward inclination angle has the highest negative correlation with athletic performance,followed by the height of the shot and the right shoulder angle at the moment of full bow.in conclusion:(1)In the throwing step phase,the cross stride length of young athletes is smaller than that of elite athletes,and the last step is longer.The last two steps do not conform to the "long-short" structure;the cross-step trunk tilts backward.Elite athletes are relatively large,deliberately pursuing overtaking equipment,causing the upper body to fall backward too much,ignoring the active overtaking of the hip axis over the shoulder axis.(2)In the final stage of exerting force,the torso tilt angle at the moment of "full bow" is slightly smaller than that of elite athletes.The right shoulder angle exceeds the reasonable range,the right elbow angle continues to decrease,the effort distance is shortened,and the "full bow" does not move.Full,hastily shot out a gun to destroy the "explosive" force.(3)Young athletes ’ left foot in front of the ground is slow and the left leg braking support ability is not as good as that of excellent athletes.The quality of left leg braking technology is an important condition for the rapid transmission of lower limbs and human momentum to the javelin.The horizontal speed of the center of gravity drops more from the moment the right foot to the left foot touches the ground,and the horizontal speed of the center of gravity when the left foot touches the ground is obviously slower than that of the elite athletes,and the speed utilization rate is not high.(4)The positive correlation between shot speed and athletic performance is the highest,followed by the cross-step trunk backward angle;the horizontal speed of the center of gravity at the moment of the last step with the left foot has the highest negative correlation with athletic performance;young athletes need to focus on improving the shot speed.Good connection between throwing step and final exertion technique.