Study On Time-domain Characteristics And Influencing Factors Of Post-activation Potentiation Of Counter-movement Jump In Volleyball Players

objectives:Comparative analysis of Post-activation potentiation(PAP)effect intervention(after 5RM parallel back squat),volleyball players in different recovery time node of countermovement jump(CMJ)height and vertical ground reaction force(v GRF)in the process of countermovement jump,peak rate of force development(p RFD),the change of the parameters such as joint Angle,discusses influence of volleyball athletes countermovement jump height and kinetic parameters of potential factors in the process of countermovement jump.In order to apply the Post-activation potentiation to the daily competition training and provide the corresponding theoretical basis for the prevention of sports injury of volleyball players.Methods: Vicon 3D motion capture system was used to monitor the changes of kinematic and dynamic parameters of 22 volleyball players before and after one 5RM parallel back squat intervention.Subjects randomized intervention group and normal group,the subjects in ATMI three-dimensional load stage complete countermovement jump movement,record baseline and after intervention respectively 2,4,6,8,10,12,14,16 minutes of countermovement jump kinematics and dynamics parameters,selection of subjects each countermovement jump eccentric contraction in phase analysis,through the Vicon Nexus 2.3 software interception of ankle,knee,hip joint Angle and the countermovement jump height data,by using of Matlab2016 a software filtering ATMI raw data,the peak rate of force development each athlete in the eccentric contraction stage was calculated.Finally,SPSS22.0 was used to analyze each parameter index after treatment.Results: 1)the PAP effect induced by 5RM parallel back squat could not significantly change the lower limb strength asymmetry index of volleyball players;PAP effect can significantly affect the change of CMJ height of volleyball players.The CMJ height of the intervention group significantly increased at the 4 and 6 minutes,while that of the normal group significantly decreased at each time node from the 8th to the 16 th minutes.At the peak of v GRF,PAP effect did not significantly change the ankle,knee and hip joint angles.PAP effect can significantly change the v GRF of volleyball players in squats and jumps.The average v GRF value of athletes in the intervention group increased significantly at the 6 and 8 minutes,while the average v GRF value of athletes in the normal group decreased significantly at all time nodes from the 6th to the 16 th minutes.PAP effect can significantly change the p RFD of volleyball players in squats and jumps.The average p RFD value of athletes in the intervention group increased significantly at the 10 minute,while the average p RFD value of athletes in the normal group decreased significantly at the 10,12 and 14 minutes.6)there is a linear relationship between the kinematic and dynamic parameters measured before the athletes squat jump and those measured after the intervention,which needs to be studied and discussed in the future.Conclusion: Volleyball players' lower limb strength asymmetry index is not affected by PAP effect.PAP effect improved the performance of volleyball players,and the optimal CMJ height was 6 minutes after the intervention of 5RM back squat.At the peak of v GRF,the PAP effect induced by 5RM back squat did not change the technical movements of volleyball players in the stretching stage.The optimal time point of PAP effect on v GRF of volleyball players is 8 minutes after intervention,and the optimal time point of p RFD of volleyball players is 10 minutes after intervention.It is necessary to analyze the pretest data as covariates in group comparison.