Eight-week Improvement Of Nordic Hamstring Exercise On Isokinetic Contraction Flexion And Extension Torque Of Knee Joint

Objective:In normal life,especially in the up and down stairs and the process of beating,the popliteal muscle will be stretched repeatedly,in addition in sports,especially in football,basketball and other sports need to run violently and rapid change of direction will appear in the popliteal muscle stretch and twist,so popliteal muscle injury is one of the most vulnerable muscles in life and sports.And according to epidemiological study,the recurrence rate of hamstring injury is the highest among lower limb motor injury,this study shows that the current protective training program and rehabilitation strategy are not very effective.This experiment is called "popliteal savior" in foreign countries This method is improved by testing the flexor torque characteristics of the knee joint through isokinetic muscle strength test and exploring the flexion and extension muscle strength characteristics of the modified Nordic posterior muscle group training and the unimproved training method.Methods:Thirty-two college students with no lower limb injuries were selected as subjects.Thirty-two subjects were randomly divided into two groups with16 persons in each group.The control group(group A)received traditional NORDIC Hamstring exercise,while the experimental group(group B)received improved NORDIC Hamstring exercise.The whole training process lasted for 8 weeks and was conducted 3 times a week.Each training group consisted of 3 groups.The Nordic posterior femoralmuscle group of each group was trained by 20 groups.The groups rested for 5 minutes.The peak torque and flexion-extension ratio of knee joint flexors and extensors were measured at angular velocities of 60/s,120/s and 180/s respectively using Swiss CON-TREX isokinetic muscle strength test and training system at the beginning and end of the training.After statistical analysis of the measured data,the influence of the improved and the first two kinds of training on the torque characteristics of knee flexors and extensors is obtained.Result:1.After 8 weeks of training,the peak torque of flexors and extensors in the control group and the experimental group increased by more than10% after training in the isokinetic centrifugal exercise test.the peak torque of flexors in the control group showed significant difference(P<0.05)when the angular velocity was 120/s,and the peak torque of flexors in the experimental group showed significant difference(P<0.05)under the three angular velocities.2.After 8 weeks of training,the peak torque of flexors and extensors in the control group and the experimental group increased in the isokinetic centripetal test.the peak torque of flexors and extensors in the control group showed significant difference at an angular velocity of 60/s(P<0.05),while the peak torque of flexors and extensors in the experimental group showed extremely significant difference at angular velocities of 60/s,120/s and 180/s(P<0.01).3.After 8 weeks of training,in isokinetic centripetal/centripetal andisokinetic centrifugal/centrifugal tests,the ratio of maximum torque /Kg of flexors in the control group and the experimental group showed significant difference(P<0.05).4.After 8 weeks of training,in isokinetic centripetal test and isokinetic centrifugal test,the peak torque ratio of knee flexors and extensors in the experimental group and the control group showed significant difference(P<0.05).5.After 8 weeks of training,the peak torque increment of flexors and extensors in the isokinetic centripetal movement test was higher in the experimental group than that in the control group under three angular velocities,and the flexors showed significant differences in angular velocities of 120/s and 180/s(P<0.05).Analysis conclusion:1.after 8 weeks of training,both the control group and the experimental group had increased the flexion and extension peak torque,and the increment was more than 15%,and the change in the experimental group was greater than that in the control group.2.After 8 weeks of training,the flexor muscle ratio of knee joint was improved,and there were significant differences compared with that before the experiment.