Study On The Effects Of Different Induction Methods On Post-activation Potentiation Of Sprinters

Post-activation potentiation（PAP）is an objectively existing physiological phenomenon,which refers to a temporary increase in muscle activity by pre-applying a specific stimulus to the muscle.Since Manning discovered this phenomenon in 1982,PAP-related research has become a hot issue in the field of sports training.However,the appearance of PAP is constrained by various conditions,including the way in which PAP is induced.Objectives: This study was conducted to investigate the change characteristics of the countermovement jump（CMJ）height,vertical ground reaction force（VGRF）,peak power output（PPO）,peak rate of strength development（PRFD）,peak impulse（PI）and integral electromyography（IEMG）value of the rectus femoris（RF）,vastus medialis（VM）,vastus lateralis（VL）,biceps femoris（BF）,tibialis anterior（TA）,and gastrocnemius（GA）at different recovery time points after static and dynamic induction of PAP in sprinters,to determine the difference between static and dynamic induction of PAP,so as to provide theoretical basis for the practical application of PAP.Methods: This study selected eight Chinese national second-level male sprinters as experimental subjects.Because of the difference of static and dynamic induction forms,this study used the VICON infrared high-speed motion capture system in the pre-experiment to collect the CMJ height data of subjects after the isometric maximum voluntary contraction（MVC）of 3s,5s,7s,and 9s and the barbell squat of 11 RM,8RM,4RM,and 1RM induction.The induction load that achieves the best PAP effect is used as the induction condition of the two induction modes in the formal experiment,so as to reduce the influence of different induction modes as much as possible.The formal experiment was carried out by means of threedimensional synchronous acquisition of VICON infrared high-speed motion capture system,AMTI force platform and Noraxon16 channel telemetry electromyography instrument,the CMJ height,VGRF,PPO,PRFD,PI and IEMG values of the RF,VM,VL,BF,TA,and GA were measured at 15 s,4min,8min,12 min,16min and 20 min after static and dynamic induction.The time interval between two experiments of the same subject was at least 48 hours.The collected data were analyzed by two-factor repeated measures analysis of variance to explore the differences between static and dynamic induction methods before and after induction,as well as the differences between static and dynamic induction methods at various time points.Results: After static induction of PAP,there were significant differences in CMJ height,VGRF,PPO,and PRFD at 4-8min recovery time（P<0.05）,and PPO and PRFD had extremely significant differences at 4min（P<0.01）.PI was significantly different at 4min（P<0.05）.The IEMG values of RF,VM,VL,BF and GA were significantly different at 4 minutes（P<0.05）,and the IEMG values of TA were significantly different at 8 minutes（P<0.05）;There were significant differences in CMJ height,VGRF,PPO,and PRFD at 8-12 minutes after PAP dynamic induction（P<0.05）,and PPO and PRFD had extremely significant differences at 8minutes（P<0.01）.PI was significantly different at 8min（P<0.05）.The IEMG values of RF,VL and GA were significantly different at 8 min（P<0.05）,and the IEMG values of VM and TA were significantly different at 12 min（P<0.05）.Conclusion: Both induction methods can induce PAP effect;the peak of PAP appears at 4minutes after static induction,and the peak value of PAP appears at 8 minutes after dynamic induction;the duration of PAP effect after dynamic induction is longer than that of static induction.