| Purpose: The purpose of this study was to compare 3 different types of PNF stretching through an experimental intervention: 1)hold-relax(HR),2)contract-relax(CR),3)hold-relax-antagonist contraction(HRC),Effects of lower limb flexibility and explosive power at different time points after stretching.It is proposed to find that a certain PNF can simultaneously improve lower limb flexibility and explosive power at certain time points,so as to solve the conflicting problem between flexibility and explosive power.Methods: 16 male track and field athletes from Anhui Engineering University were selected as the experimental subjects.A pre-experiment was performed before the experiment to determine the stretched position of the PNF.The formal experiment was conducted in 3 times,and 16 subjects participated in 3 different types of PNF stretching experiments,with a one-week interval between each experiment.Seated forward flexion and standing long jump were selected as experimental test indicators.After the warm-up,seated forward flexion and standing long jump were tested as the pre-experiment results.Immediately after stretching,5minutes,10 minutes,15 minutes,and 20 minutes were tested for seated forward flexion and standing long jump.Paired samples t-test was used to compare the changes of indexes before and after within the group,and one-way analysis of variance was used to compare the indexes between groups.Results: Research results: In the preliminary experiment,the PNF stretched to the maximum position can develop flexibility more effectively than the PNF that is not stretched to the maximum position.Therefore,in the formal experiment,the three PNFs are stretched to the maximum position.The first type,the PNF paired sample T-test results of the hold-relax group showed that there was a significant difference in the performance of sitting forward flexion at 10 minutes after the experiment and immediately after the warm-up(P<0.05),and at 5 minutes,15 minutes,and 20 minutes after the experiment.There is a very significant difference(P<0.01),and there is no significant difference immediately in the experiment.There were significant differences in standing long jump scores at 5 minutes,10 minutes,15 minutes after the experiment and immediately after the warm-up(P<0.05),but there was no significant difference between immediately after the experiment and 20 minutes after the experiment.The second type,the PNF paired sample T test results of the contraction-relaxation group showed that there was a significant difference in the performance of sitting forward bending at the moment of the experiment and immediately after the warm-up(P<0.05).There was a very significant difference in minutes(P<0.01).There was a significant difference between the standing long jump scores 5 minutes after the experiment and the immediate warm-up(P<0.05),and the immediate long jump scores at 10 minutes,15 minutes,and 20 minutes after the experiment were significantly different from the warm-up immediately(P<0.01).No significant difference.The third type,hold-relax-antagonist muscle contraction PNF paired sample T-test results showed that there were significant differences in the performance of sitting forward flexion at 5 minutes,10 minutes,and 20 minutes after the experiment(P<0.05),and 15 minutes after the experiment.Very significant difference P<0.01,there is no significant difference immediately in the experiment.The significance level of standing long jump scores at each time point after the experiment was greater than 0.05,and there was no significant difference.The results of one-way ANOVA of sitting forward flexion between groups showed: P>0.05,no significant difference between experimental group I and experimental group II;P>0.05,no significant difference between experimental group I and experimental group III;There was no significant difference between the experimental group II and the experimental group III,P>0.05.The results of one-way analysis of variance in standing long jump between groups showed that: P>0.05 between experimental group I and experimental group II,no significant difference;P<0.05 between experimental group I and experimental group III,with significant difference;There was a significant difference between the experimental group II and the experimental group III,P<0.05.And at some time points,P<0.01,there is a very significant difference.Conclusion:(1)3 different types of PNF stretching can improve lower limb flexibility,and the flexibility improvement effect is the best at 20 minutes after the experiment.(2)Three different types of PNF stretching had different effects on lower extremity explosive power.PNF in the hold-relaxation group inhibited the explosive power of lower limbs;PNF in the hold-relaxation-antagonist muscle contraction group improved the explosive power of lower limbs at some time points,but not significant;,15 minutes,and 20 minutes at the same time improved the flexibility and explosive power of the lower limbs,and it was significant. |
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