Study On The Strength Changes Of Quadriceps Femoris After Special Warm-up With Different Contraction Forms

Research purpose: Warm-up exercise is an indispensable means to improve sports performance,which has a positive impact on competition and training.In order to complete the study,the purpose of this experimental study is to evaluate and analyze the strength of quadriceps femoris by measuring the performance of lower limb muscles through s EMG after the specialized warm-up of quadriceps femoris in different contraction forms,and then through the results of the longitudinal jump test(SJ),The static strength test of the quadriceps femoris after different forms of exercise and non-shrinking exercise was carried out for strength analysis.The test results can obtain the maximum strength,explosive strength and other data of the quadriceps femoris static contraction.Through the selection and analysis of the above parameters,the muscle strength ability of quadriceps femoris is evaluated,the strength change is discussed,the mechanism is revealed,and the reason for the strength change is analyzed.Research methods: This study mainly uses the method of literature and experiment to recruit all the students in Xi’an Institute of Physical Education.This study selects 10 students majoring in physical education,determines the three warm-up exercise methods of different forms of muscle contraction in this study through literature review and expert interviews,and uses surface electromyography and dynamometer to test the longitudinal jump experiment of the experimental subjects,The static strength test of the quadriceps femoris of the experimental subjects was carried out by using a tensiometer.After the experiment,all the experimental data were uniformly tested,and the experimental data of the subjects who had not warmed up were compared,and finally statistical analysis was carried out.Research results:1.The static strength test was carried out after warm-up exercise of different contraction forms of quadriceps femoris muscle.The test results showed that after the centrifugal warm-up exercise,the starting force of the centrifugal warm-up exercise group was 5.92 ± 3.90 kg,the explosive force was 186.88 ± 140.29kg/s,the maximum force was 60.36 ± 6.63 kg,and the relative force was 0.84 ± 0.14kg/kg.The statistical analysis was conducted with the non warm-up group,P=0.133>0.05,P=0.097>0.05,P=0.002<0.01,P=0.007<0.01.By statistical analysis,the maximum strength of quadriceps femoris muscle after eccentric training is significantly different from that without warm-up.The relative strength of quadriceps femoris muscle was significantly different from that of non warm-up.2.Comparative analysis of three different warm-up exercise methods,using statistical methods to analyze the time spent in the air,found that there was a significant difference in P=0.006<0.01 between the centripetal warm-up exercise group and the centrifugal warm-up exercise group.P=0.836>0.05 for the centripetal warm-up exercise group and the isometric warm-up exercise group,with no statistically significant difference.There is a significant difference in P=0.003<0.01 between the equal length warm-up exercise group and the centrifugal warm-up exercise group.Using statistical methods to analyze the takeoff height,it was found that there was a significant difference in P=0.002<0.05 between the centripetal warm-up exercise group and the centrifugal warm-up exercise group.There was no significant difference in P=0.882>0.05 between the centripetal warm-up exercise group and the isometric warm-up exercise group,and there was no statistical significance.There is a significant difference in P=0.002<0.01 between the equal length warm-up exercise group and the centrifugal warm-up exercise group.Using statistical methods to analyze the takeoff speed,it was found that there was a significant difference in P=0.006<0.01 between the centripetal warm-up exercise group and the centrifugal warm-up exercise group.P=0.832>0.05 between the centripetal warm-up exercise group and the isometric warm-up exercise group,with no significant difference or statistical significance.There is a significant difference in P=0.003<0.01 between the equal length warm-up exercise group and the centrifugal warm-up exercise group.3.After warming up the quadriceps femoris muscle in different contraction forms,we conducted a longitudinal jump experiment.The test results showed that the comparison of s EMG values of lower limb muscles after standardization had changed significantly.RMS and i EMG discharge of rectus femoris,lateral thigh muscles and medial thigh muscles were significantly higher than those of biceps femoris muscle,semitendinosus and gluteus maximus,especially the discharge of quadriceps femoris muscle after centrifugal warm-up exercise was significantly higher than that of other groups,It can be seen that the activation degree of quadriceps femoris muscle after centrifugal warm-up exercise is higher,and more muscle fibers are recruited.Research conclusion:1.After centrifugal warm-up exercise of quadriceps femoris muscle in different forms of contraction warm-up exercise,the maximum strength and relative strength of quadriceps femoris muscle static contraction significantly increased.There is no significant change in the starting force and explosive force.2.After the warm up exercise of quadriceps femoris muscle in different contraction forms,the performance of the warm up exercise group with different contraction forms in the vertical jump experiment has significantly improved compared with the non warm up group,especially the centrifugal warm up exercise group,which has significant differences compared with the other two groups,which can be concluded that quadriceps femoris muscle has significantly improved the overall strength of the lower limbs after the centrifugal warm up exercise.3.In the longitudinal jump experiment,the s EMG value of the standardized lower limb muscles has a significant change.The RMS and i EMG discharge of the rectus femoris,lateral femoris,and medial femoris are significantly higher than those of the biceps femoris muscle,semitendinosus,and gluteus maximus.In particular,the discharge of the quadriceps femoris muscle after the centrifugal warm-up exercise is significantly higher than that of other groups.It can be seen that the quadriceps femoris muscle is more activated after the centrifugal warm-up exercise,and more muscle fibers are recruited.