Effects Of Flywheel Resistance Exercises With Different Inertia Loads On The Post-Activation Potentiation After Vertical Jump In Young Males

Objective:The purpose of this study is to observe the effects of flywheel resistance exercises with different inertia loads and traditional barbell resistance exercises on young males,and to investigate the effects of flywheel resistance exercises with different inertial loads on the post-activation potentiation（PAP）after vertical jump.Methods:Eighteen young male subjects（2 of them withdrew form the study due to injury）with resistance training experience（1RM half-squat weight is more than 1.5times its own body weight）were selected and randomly（72-hour intervals）crossed for traditional barbell exercise（90%1RM,1×5 groups,1 minute interval between groups）and inertia flywheel resistance exercise（flywheel specifications:Large,radius 0.14m,mass 2kg,Large+Large,LL;Large+Pro,LP;Pro,radius 0.14m,mass 6kg,Small,radius 0.11m,mass 0.6kg,Large+Small,LS,6 times×3 groups,3 minutes interval between groups）.The PAP effect was evaluated by the CMJ that was performed immediately（within 15s）and at the 4^th,8^th,12^th minute after the end of the activating exercise,erform a counter movement jump（CMJ）test on the force plate,at the same time collect muscle electrical signals.Then the changes of kinematic（CMJ height,jump speed,buffer time,elongation time）,dynamics（standardized peak power,standardized kick extension impulse,standardized maximum ground reaction force）and the integrated electromyography（iEMG）of the main muscles of the lower limbs（gluteus maximus,rectus femoris,biceps femoris,lateral femoris,medial femoris,and lateral gastrocnemius）was analyzed.Results:（1）Both the practice methods can produce PAP of CMJ,but the time of PAP appearing is different.The specific performance of each parameter are as follows:CMJ height（m）is shown as LL group（immediate,4,8,12min,0.522±0.081,0.529±0.080,0.539±0.085,0.538±0.075）,LP group（immediate,4,8,12min,0.524±0.074,0.542±0.075,0.552±0.078,0.540±0.071）,LS group（4,8,12min,0.532±0.074,0.533±0.083,0.534±0.069）and barbell group（4min,0.531±0.07）compared with baseline,they have a significant increase（P<0.05）;jump speed（m/s）increased significantly compared with baseline（LL,4,8min,3.15±0.29,3.14±0.31;LS,4,8,12min,3.13±0.29,3.15±0.30,3.11±0.28;LP,4,8,12min,3.11±0.26,3.18±0.26,3.16±0.26;P<0.05）;the standardized peak power（W/kg）increased significantly compared with the baseline（LL,4min,32.960±4.153;LS,8,12min,32.862±5.954,31.565±5.454;LP,4,8min,33.241±5.056,33.426±4.926;P<0.05）;the standardized kick-stroke impulse（BW·s）was significantly higher than the baseline（LL,immediate,8,12min,0.300±0.02,0.307±0.02,0.307±0.02;LS,immediate,4,8,12min,0.301±0.02,0.300±0.02,0.313±0.02,0.306±0.02;LP,8,12min,0.311±0.02,0.309±0.02;barbell group,4min,0.302±0.03;P<0.05）;gluteus maximus（LL,8,12min,49.29±9.75,46.38±8.85;LS,8,12min,46.63±10.86,44.53±10.95;LP,4,8,12min,46.51±12.24,51.82±10.10,49.02±12.43;barbell group,4,8,43.37±7.10,41.14±6.92）and rectus femoris muscle（LS,4,8min,96.63±16.42,98.92±16.41;LP,4,8min,102.28±23.82,105.44±23.02）all showed significant（P<0.05）increases in iEMG（u V·s）,and there were no significant difference（P>0.05）between other muscles compared with baseline;（2）There were significant changes in diffrerent inertia loads only at the standardized peak power（LP group is higher than LL group,8min）（P<0.05）;（3）The height of CMJ was significantly increased at 8 and 12 minutes after the intervention in the LP group compared with the barbell group（P<0.05）.The iEMG of the gluteus muscle was increased significantly at 8 and 12 minutes after the intervention in both the LL and LP group compared with the barbell group（P>0.05）.Conclusions:（1）Both inertial flywheel resistance exercises and traditional resistance exercises can produce PAP after vertical jump.（2）The inertia flywheel resistance exercise is more effective than the traditional barbell exercise to induce PAP after the vertical jump.（3）The magnitude of the inertia load has a relationship with the effect of the PAP after vertical jump.The larger inertia load used in this study can produce better results.