Experimental Study On The Effect Of Plyometric Training On The Explosive Force And Displacement Velocity Of Lower Limbs In Junior High School Students

Purposes:By reviewing relevant literature,fast-stretching compound training is a training method that is often used by athletes to improve bounce and speed.Since some people believe that rapid-stretching compound training requires a certain strength foundation,few people are concerned about this kind of training.Whether the method is also suitable for junior high school students to conduct experimental research,but foreign experts and scholars have applied rapid expansion and contraction training to the elderly and children,and achieved good empirical results.The physical health of junior high school students in my country has always received extensive attention from all walks of life.The explosive power and displacement speed of students’ lower limbs are closely related to the junior high school students’ physical education entrance examination and exercise level.After understanding,the main methods of lower limb training in daily physical education classes are It is a variety of self-weight squatting and in-situ jumping.Therefore,this paper hopes to combine low-intensity fast-stretching compound training based on low hurdles with school teaching methods,and compare it with the routine lower limb training methods in daily physical education classes.To explore whether this rapid stretching training method can also significantly improve the explosive power and displacement speed of the lower limbs of junior high school students,so as to find a training method that is more suitable for improving the explosive power and displacement speed of the lower limbs of ordinary junior high school students in school physical education teaching.Method:In this paper,the method of literature,expert interview,experiment,and mathematical statistics was used to explore the effect of rapid stretching compound training on the explosive force and displacement velocity of lower limbs of junior high school students.In the experiment,students from two classes in the second grade of Shanghai Jiayi United Middle School were selected for the control experiment.There were 15 boys and 15 girls in the experimental group and the control group.The experimental period was 12 weeks.The experimental group adopted fast-stretching compound training,and the control group adopted daily training methods.Shapiro-Wilk was used to test the normality of the pre-test data before and after the experiment,the independent samples t test was used to compare the experimental group and the control group before and after the experiment,and the paired samples t test was used for the experimental group and the control group after the experiment.Intra-group comparison,and use excel software to calculate the effect size(ES)of the data before and after the group,and compare the difference between before and after(0.2≤ES<0.5 is a small effect size,0.5≤ES<0.8 is a medium effect size,0.8≤ES is a large effect size.effect size).Results:(1)Before the intervention,there was no statistically significant difference between the experimental group and the control group in terms of physical conditions and test indicators(p>0.05).(2)Boys and girls in the experimental group showed larger effectsizes before and after the experiment.The 30-meter accelerated running and standing long jump of the boys and girls in the experimental group both produced relatively high effect sizes(ES≥0.8),and the 50-meter running and vertical jumping both showed moderate effect sizes(0.5≤ES<0.8).Before and after the experiment,boys and girls in the experimental group showed extremely significant differences in the four test indicators compared with those before the experiment(p<0.01).There were also significant differences between boys and girls in the control group before and after the experiment(p<0.05).The standing long jump scores of boys and girls in the control group showed a moderate effect size before and after the experiment(0.5≤ES<0.8),30 sprints,50 Meter running and vertical jumping and touching height all showed small effect size(0.2≤ES<0.5 is a small effect size),and the control group showed a significant difference after the experiment compared with before the experiment(p<0.05).(3)After the experiment,the independent sample t test was performed on the experimental group and the control group.The experimental group and the control group showed significant differences in the standing long jump and vertical jump touch height test scores(p<0.05).There was no significant difference between the acceleration run and the 50-meter run(p>0.05)。Conclusions(1)The lower extremity explosive force and displacement speed of the experimental group and the control group were significantly improved before and after the experiment,indicating that the rapid stretching compound training and daily physical education training methods have positive effects on the lower extremity explosive force and displacement speed of junior high school students.Effect.(2)In terms of improving the explosive power of lower limbs,the training method based on small hurdles and low jump boxes has a better effect than training methods such as self-weight squatting and jumping in place.In the future,this kind of rapid expansion and contraction can be adopted in the classroom.The compound training method improves students’ lower body explosive power.(3)There is no significant difference between the experimental group and the control group in the improvement of displacement speed.This training method has no significant difference from the daily training method in improving the displacement speed of junior high school students.