A Biomechanical Comparison Research On Landing Movement During Active And Passive Buffering

Research Purpose:To explore the difference in kinematic and kinetic characteristics between active and passive buffering landing movement under the same conditions,analyze and compare the buffering effect and the intrinsic mechanism of different ways of buffering landing action.,and provide reference for related studies of reducing the probability of lower extremity injuries caused by improper buffering during ground movement.Research Method:Twenty undergraduates from Jilin University were selected(age: 23.1±0.8 years old;Height 176.4±5.5 cm;Weight: 72.8±9.1 kg).Using active and passive buffering of two different landing,respectively from the height of 45 cm,60 cm of homemade flap on the free fall to the ground movement.The 3 d motion capture system(Vicon T20,50 hz)and Force Plate-1.0,and the methods of Surface electromyography system(DELSYS-EMGworks-4.3.1)were used to collect kinematic and kinetic and electromyographic data from buffering landings.5 valid data were collected for each height each,and 20 time of data were collected for each subject,10 for the active group and 10 for the passive group.Research Result:(1)In the biomechanical test,the active buffer landing group was better than the passive buffering landing group in the buffer time,the first peak of vertical ground reaction,the interval time between the first peak and the second peak,knee joint moment,angular velocity,ankle joint moment and other indexes at different heights.The buffer time of active group of was longer than the other group(p<0.05).(2)The maximum peak ground reaction force in the active group was significantly smaller than that in the passive group(p < 0.05).The interval between the first peak and the second peak of the ground reaction force in the active group was significantly greater than that in the passive group(p < 0.05).At the same height of descent,the peak knee moment was greater(p < 0.05)and the maximum angle was smaller,the peak ankle moment was smaller,and the peak hip moment was not significantly different but the angle was smaller(p < 0.05)in the passive group.(3)The IEMG of related muscle groups such as gastrocnemius,tibialis anterior,and medial femoral muscles were greater in the active buffer group than in the passive group,and the muscle contribution of tibialis anterior in the active group was less than that of the passive group,while the contribution of biceps femoris in the active group was greater than that of the passive group.Research Conclusion :(1)At the same height,the overall joint angle change of the landing active buffering group is greater,which is more conducive to prolonging the cushioning process and reducing the peak impact.(2)At the same height,The maximum peak of the ground reaction force of the active buffering group is small,the second peak is also small,and the buffer time is longer.and the interval between the first peak and the second peak value is longer.Therefore,the GRF shock of the active group was more gentle and lasted longer,which was conducive to reducing the generation of damage,but the buffer efficiency was not as high as that of the passive group.(3)The maximum extension moment and internal rotation moment of the knee produced by the active buffering landing were smaller than those of the passive cushion landing,and there was no significant change in the abduction moment,the maximum top flexion moment of the ankle joint was small,and the maximum external rotation moment of the hip joint did not change significantly,indicating that the active buffering could reduce the maximum load of the joint on the external force,and the overall peak moment of each lower limb was related to the drop height,and the higher the drop height,the larger the peak moment.(4)There was "pre-activation" in the muscles related to active buffering,and the IEMG of muscle was greater than that of the passive cushion,indicating that more muscle fibers were recruited in the active group and more work was done by the muscles.There was no significant difference in the muscle contribution rate,only the tibialis anterior and biceps femoris muscles were different in the active and passive groups,indicating that the active and passive modes had a greater impact on the individual muscle work,but less on the overall contribution rate of the landing movement.