The Post-activation Potentiation Effect On Muscle Activiation Of Athletes At Different Training Levels

Post-activation potentiation means contraction of human body muscle and increase of low frequency tetanic force after contraction stimulus under certain conditions.Post-activation potentiation is a phenomenon of muscle movement ability improvement caused by muscle contraction experience(memory).Aforementioned contraction stimulus under certain conditions include passive electric stimulation induction and active muscle contraction(maximum voluntary isometric contraction,biggest or bigger strength load).Furthermore,such conditioning stimuli enhance not only the muscle twitch properties but may also potentially enhance muscle performance,when explosive tasks such as jumping or sprinting are tested.Object: The aim of this study was to determine the recovery time and training levels required to observe enhanced muscle preformance followed by 5 sets of 1 repetition at 90% 1RM in the parallel back squat with1 minutes rest between sets.Comparing and analyzing the impact of recovery time and training level on PAP,which provides a theoretical basis for applying PAP to actual training and competition.Methods: This research choose fourteen Chinese male track athletes as experiment object,divided into two groups according to the training levels,higher level group and lower level group.Testing the kinematics,dynamics and sEMG data which include the height of countermovement jump,the joints angle,the peak ground vertical reaction force,peak power output,the rate force development,the peak impulse,integrated Electromyography after heavy resistance training(1 set of 5 repetitions at 90% 1-RM)in different recovery time(15s,4min,8min,12 min,16min,20min)and analysing it.Results: The peak ground vertical reaction force,peak power and RFD of the kinetic index were significantly higher than the baseline value(P<0.05).There was no significant difference in hip,knee and ankle angles at the peak force moment in the kinematic parameters.However,there was a significant increase in the height of CMJ at the recovery time of 8 min(P<0.05).When the recovery time was 8 min,the iEMG of the muscles(rectus femoris,vastus lateralis,vastus medialis,gastrocnemius)of CMJ was significantly increased(P<0.05),but the iEMG of the muscles(biceps femoris,tibialis anterior)of CMJ was no significant difference(P>0.05).The training level factors were significantly different between the kinematics index(CMJ height),the kinetic index(PPO,vGRF)and the iEMG of some muscles(rectus femoris,vastus lateralis)(P<0.05),the other index were no significant difference(P>0.05).Conclusion:In the PAP induction mode of 5 times 90% 1RM weight squat(1 min each time),the effective period of PAP effect is 4-12 min,reaching the peak at 8 min,mainly reflected in the lower squat height and the peak ground vertical force.The peak power,RFD,and countermovement jump have increased the integral myoelectric value of the main muscles(the rectus femoris and the lateral femoral muscles),which enhances the ability of the subject to recruit motor units,increases muscle activity,and increases explosive power.Different training level factors have significant influence on the PAP effect,and the performance of the higher level athlete PAP is more significant on the lower jump.