Effects Of Different Fixed Resistance Training Methods On Hamstring Muscle Strength And SEMG Signal

Objective:The posterior femoral muscle group is the main muscle group that is easy to be injured in the knee joint movement,and the balance of force between the anterior and posterior muscles of the knee joint is the main factor that affects the injury of the posterior femoral muscle group.Different training methods will affect the strength and muscle activity of the lower extremity muscle groups,and there are significant differences in biomechanical characteristics between the near and far fixed work of human muscles.In this paper,two training methods of proximal and distal fixation of posterior femoral muscle group were adopted.The main purpose of this paper is to observe the changes of lower limb strength and the characteristics of muscle electrical signal in 8-week proximal fixation and distal fixation,so as to provide some reference for the prevention of injuries of posterior femoral muscle group and the development of training programs.Methods:Twelve female subjects were randomly divided into two groups:group A was far fixed training group(n=6),group B was near fixed training group(n=6).The training period is 8 weeks.The training load is 10rm.The training amount is 8 times/group 3 groups.The interval of each group is 3min.Before and after the training,the dynamic parameters of knee flexion and extensor torque were measured by the control x isokinetic muscle strength test system,and the surface electromyography(sEMG)collected by the BIO VISION bioelectricity recording and analysis system was used to record the integral electromyography(iEMG)and root mean square amplitude(RMS)of 8 repeated training actions before,4 weeks and after the training.The relevant test results were statistically processed and compared.Results:1.The training methods of near fixation and far fixation have significant effect on the improvement of muscle strength of posterior femoral muscles.After 8 weeks of far fixation training,the flexor peak torque increased significantly(P<0.01)in centripetal 60 °/s,centripetal 180°/s and centrifugal 60 °/s,but there was no significant difference in extensor peak torque in centripetal 60 °/s and centripetal 180 °/S(P>0.05),and centrifugal 60°/s and centrifugal 180°/s increased significantly(P<0.01).Only when the angular velocity was 60 °/s,the routine ratio and functional ratio of H/Q increased significantly(P<0.05).After 8 weeks of near fixation training,flexor peak torque increased significantly in centripetal mode(P<0.01),but no significant difference in centrifugal mode(P>0.05);extensor peak torque only increased significantly in centripetal mode(P<0.05).The routine ratio of H/Q of knee joint increased significantly(P<0.01)when the angular velocity was 60 °/s and 180°/s,while the functional ratio had no significant difference(P>0.05).There was no significant difference between the two training modes(P>0.05)in the increase of flexor peak torque and extensor peak torque in centripetal mode(P<0.01).2.After training,the IMVC of biceps femoral and semitendinosus muscle in the two groups increased significantly(P<0.05).The iEMG of rectus femoral in the two groups increased significantly after four weeks and after training compared with that before training(P<0.01).After 4 weeks of training,the iEMG activity of biceps femoral(P<0.01)and semitendinosus muscle(P<0.05)in the two groups was significantly different,and the iEMG activity in the near fixed group was higher than that in the far fixed group.There was no significant difference in the muscle CO activation ratio of the far fixed training group before and after the training(P>0.05),but there was significant difference in the muscle CO activation ratio of the near fixed training group before and after the training(P<0.05).The contribution rate of biceps femoral and semitendinosus femoral was higher than that of rectus femoral,lateral femoral and medial femoral.The contribution rates of rectus femoral,lateral femoral and medial femoral were significantly different(P<0.01),except for the long head and semitendinosus of biceps femoral.Conclusions:1.The two training methods of far fixation and near fixation have obvious effect on the improvement of muscle strength of posterior femoral muscles.Far fixation training can improve the strength of the posterior femoral muscles more significantly.Far fixation training can increase the centrifugal muscle strength and improve the strength of the posterior femoral muscle group.By increasing the ratio of the knee flexion and extensor muscles,the balance of the knee flexion and extensor muscles before and after the knee joint can be improved and the sports injury can be reduced.The training of posterior femoral muscle group also helps to antagonize the increase of muscle strength.However,the two training methods should be used according to the actual situation.2.Different training methods lead to different changes of muscle activation level.The iMVC value of biceps femoral and semitendinosus in the far fixed training group was significantly higher than that in the near fixed training group.The results show that the far fixation training method has more obvious activation effect on the muscle,and can recruit more biceps femoral and semitendinosus muscle to participate in the exercise,which makes the activation effect of biceps femoral long head and semitendinosus muscle significant,the contribution rate of muscle is higher,and the contribution rate of rectus femoral is also improved.Training can increase muscle strength and improve muscle activation level by changing the coordination ability among active muscle,synergetic muscle and antagonistic muscle,so as to prevent sports injury.