The Impact Of Video Feedback At Different Times On The 100m Technique And Performance

Objective:Video feedback has been widely used in sprint training of competitive sports field,but the timing of feedback has not yet reached a consensus.This study used immediate video feedback and delayed video feedback methods to intervene in amateur sprinters;observed the changes of the 5 technical parameters:knee angle of the front leg at the start,hip angle of the front leg at the start,hip angle during running,the landing cushion angle,and the center of gravity projection,and the effects of all these technical parameters on 100-meter performance;explore mechanism that the timing of video feedback generated,seeking the effective way to improve 100-meter performance,providing scientific and effective training way for 100-meter sprinters in sports school.Methods:18 participants were recruited from short-sprint teams in Nantong Sports School(12 boys,6 girls,aged 12 to 17 years,mean age =13.8 years),divided into immediate feedback group and delayed feedback group according to the method of homogenous grouping.9 People in each group took four times interventions for five weeks;during each training session,the subject’s technical movements were videotaped.According to five technical parameters(knee angle of the front leg at the start,hip angle of the front leg at the start,hip angle during running,the landing cushion angle,and the center of gravity projection),giving feedback by viewing the video.Immediate feedback group members were given feedback immediately after each practice;delay feedback group members were given feedback at the end of the training class.The pre and post 100 meters test performance were recorded and videotaped at the same time,using the point software to analyze the video,calculate the relevant angles of 5 technical parameters,analysis of changes in the angles and its impact on 100 meters performance;using SPSS22.0 to perform paired sample T-test and independent sample T-test on data.Results:After the five-week intervention,(1)there were significant improvement in 100-meter performance in both two groups(P<0.01);(2)The delayed feedback group performance of improvement was significantly better than the immediate feedback group(P<0.05);(3)delayed feedback in 5 technical parameters(knee angle of the front leg at the start,hip angle of the front leg at the start,hip angle during running,the landing cushion angle,and the center of gravity projection)In addition to the hip angle during running,the other four parameters were significantly different(P<0.05).The immediate feedback group only significantly improved on the knee angle of the front leg at the start(P<0.05),and other parameters had no significant changes.(P>0.05);(4)There was a significant difference in the range of change in the knee angle of the front leg at the start between the delayed feedback group and the immediate feedback group(P<0.05),and there was no significant difference in the other parameters(P>0.05).Conclusion:1、Both delayed feedback and immediate feedback can have a positive effect on the performance of 100-meter due to the change of technique.Delay feedback is more conducive to the change of technique than immediate feedback.The change of technique is the main reason for the better 100-meter performance.Both delayed feedback and immediate feedback can improve the performance of 100-meter,but the delayed feedback is played as a better role.2、Both delayed feedback and immediate feedback can have a positive effect on the performance of 100-meter due to the change of technique.Delay feedback is more conducive to the change of technique than immediate feedback.The change of technique is the main reason for the better 100-meter performance.Both delayed feedback and immediate feedback can improve the performance of 100-meter,but the delayed feedback is played as a better role.