Effects Of Repeated Drop Jumps Among Different Heights On Lower Extremities Muscle Simulation Of Countermovement Jumps With Different Training Volumes

Purpose: The countermovement jump（CMJ）was used to evaluate athletes’ lower extremity jumping ability and athletic performance.The drop jump（DJ）is an effective plyometric training method that is widely used to improve athletes’ jumping performance.The main purpose of this study was to investigate the effects of different highly repetitive DJ training on CMJ motor performance,bilateral asymmetry and lower extremity muscle activation by means of muscle simulation.Methods: 18 male athletes were selected to perform 5 sets（50 DJ in each set）at 3different（drop jump height）30cm,DJH40 cm,DJH50cm.Five sets of 3（each set）CMJ were performed after the 50 th,100th,150 th,200th,and 250 th DJ,respectively.The mean values of（Countermovement jumps50,CMJs100,CMJs150,CMJs200,and CMJs250）in each group were taken as data analysis.10 infrared BTS motion capture cameras and 2 force plates collect data.MATLAB one-way repeated ANOVA for differences between 3 different DJ heights of5 CMJs.If there was a significant difference（P<0.05）,the least significant difference method was used to compare the results of 3 different heights of 5sets CMJ.Results: Within CMJs200,CMJ performance was DJH50 > DJH40,DJH30.At 250 CMJs,CMJ performance was DJH50 < DJH40 and DJH30.Within CMJs100,the bilateral asymmetry of CMJ was DJH50 < DJH40 and DJH30.When CMJs150,CMJs200,and CMJs250,the CMJ bilateral asymmetry was in DJH50 > DJH40,DJH30.In CMJs200,the main muscles activation of CMJ at DJH50 > DJH40 and DJH30.When CMJs250,the main muscles activation of CMJ at DJH50 < DJH40 and DJH30.Conclusion: In order to increase the CMJ performance and muscle activation,and reduce the risk of injury,it is recommended not exceed DJH50 cm and 200 DJ times.