| Background: Women's 20 km race walking is an official event of the Olympic Games,World Championships and World Cup.At present,the field of women's 20 km race walking is mainly studied with a single entry point of "speed" or "technique ".The race walking event has the dual characteristics of "speed-race" and " technique-race"."Speed" and "technique" are important factors that affect the final result of the race walking.Purpose: Based on the integration of previous research results,combined with the training practice of the national race walking team,this study takes "speed" and "technique" as the main lines,conducts a comprehensive and in-depth analysis of the dual characteristics of "speed-race" and " technique-race ",and discusses the pacing profiles and the technical characteristics in different speed zone.The aim of this study is to provide theoretical reference and practical support for scientific training and competition of outstanding women's 20 km race walks.Methods: The survey method,interview method and document method were used to collect a large amount of primary data,observe and record the training situation of the test subjects,and obtain training and competition data.A quasi-experimental was designed to collect information on the women's 20 km race walking at the Tokyo Olympics and the Rio Olympics,and analyze the pacing profiles of the two Olympics.Use 3D biomechanical test method to collect video data of elite women's 20 km race walkers,and use Ariel performance analysis system and Dartfish6.0 to explore the technical characteristics of race walking in different speed zone.Use case studies to analyze the pacing profiles and race walking techniques in different speed zones of Olympic champions.Use Microsoft excel2010 to organize and summarize relevant data,and use spss25.0 to make statistics analysis.Results:1.The average age of the elite female 20 km race walkers was 27.48±5.12 years old when they participated in the Olympic Games,and there was no significant difference in the age of the four groups of athletes participating in the Olympic Games(p>0.05).The best performance and 10 km race walking results of medalist group better than other groups(p<0.01).The peak speed,minimum speed and sprint speed were significantly different between groups(p<0.01),and there was a significant difference between groups in starting speed(p<0.05).Minimum speed,sprint speed and peak speed were significantly positively correlated with race performance(p<0.01),and speed difference was significantly negatively correlated with race performance(p<0.01).The correlation between each speed index and the competition performance is sprint speed > minimum speed > peak speed > starting speed,and the correlation effect between sprint speed and competition speed is the largest(r=0.833).2.Athletes who have reached the international standards in the women's 20 km race walking in the two Olympic Games have a total of 1 knee bend warning with the race speed of 4.17m/s,32 times of flight warning with the speed of 3.83±0.13m/s,9 times flight fouls with the speed of 3.93±0.11m/s,the race speed of the medalist group when fouling is significantly higher than that of the <5% winning time group(p<0.05).3.In different speed zones,there was no significant difference in the vertical displacement(p>0.05).There was also no significant difference in the knee joint angle of the supporting leg at initial contact and vertical upright position(p>0.05).4.Step length/height(r=0.522,p<0.01),multiple step length(r=0.4299,p<0.01),single step length(r=0.4250,p<0.01),cadence(r=0.438,p<0.01),flight distance(r=0.450,p<0.01)had a very significant correlation with race speed,and increased significantly with the increase of race speed in 3 speed zone(p<0.01).Foot behind distance(r=0.214,p<0.05)had a significant correlation with race speed,and it was significantly larger in the high-speed zone than in the low-speed zone(p<0.05).The hip joint speed of the supporting leg(r=0.216,p<0.05)and hip joint speed of swinging leg(r=0.186,p<0.05)had a significant correlation with competition speed,and it was significantly larger in high-speed zone than in low-speed zone(p<0.01)and medium-speed range(p<0.05).The angle between the two thighs at toe-off(r=-0.435,p<0.01)was negatively correlated with the speed of the race speed,and was significantly smaller in the high-speed zone than in the low-speed zone(p<0.01).5.The race speed that Liu Hong broke the world record was distributed in the medium-speed zone and the high-speed zone.The average race speed that she broke the world record was 3.95m/s,which was greater than the original world record of3.93m/s.Liu Hong's multiple step length,single step length,step length/height,cadence,the foot ahead distance and flight distance in the high-speed zone were significantly greater than those in the medium-speed zone(p < 0.01).Conclusion:1."Speed-race" and " technique-race" are a pair of contradictory unity.They are the dominant competitive ability of race walking.They play a dominant and decisive role in the winning factors of race walking competitions.The competition between high-level women's 20 km race walkers is often the coexistence of "speed" and "technique".2.The pacing profiles are closely related to the level of competition.The "Speed-race" ability of excellent women's 20 km race walkers is the basic guarantee for the final victory of the competition.Higher average speed and sprint speed are the key indicators of winning the competition.3.The supporting leg landing technique of the elite women's 20 km race walkers basically conforms to the definition of the race walking rules,and knee-bending fouls rarely occur.With the increase of the race speed,the center of gravity of the elite women's 20 km race walkers is relatively stable and fluctuates less,without obvious fluctuations.The high-speed zone is the frequent speed zone of warnings or fouls for the elite female 20 km walkers.The higher the competitive level of athlete,the faster she race walking when fouling.When athletes of the same competitive level keep the same pacing profiles the technique of race walking at high speed is the key index that affects the result of competition.4.The technical characteristics of athletes in different speed zones are as follows: as the step length increases,the foot behind distance increases.As the cadence increases,the angle between the thighs at toe-off becomes smaller.The increase of the flight distance and flight time increase the risk of technical fouls.The hip joint of the swing leg swings actively,and the support leg rolls to the ground,reducing the loss of race speed.The swing speed of the elbow joint of the upper limb increases,the back swing angle of the forearm does not change significantly,and the angle between the elbow joint of the forearm become smaller.5.The pacing profiles and technical characteristics of the champion athletes reflect the highest level of competition in the women's 20 km race walking competition.The champion athletes showed a technical style of "long step lengths" and "high cadences" in the competition. |
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