Effects Of 6-week Sand Fast-stretching Compound Training On The Rapid Strength Of The Knee Joint In Healthy Young Men

Objective: In this study,we observed the effect of fast telescopic compound training on the fast strength of healthy young men's knee joints under two different training interfaces of sand and hard ground for 6 weeks,and discussed the sports performance characteristics and mechanical mechanism of the training effect from the perspectives of kinematic parameters and dynamics respectively.Method: Sixteen healthy young male subjects selected were randomly divided into sand group(8 persons)and hard ground group(8 persons)by experiment method,and the same rapid expansion and contraction compound training plan was implemented at two interfaces(sand and hard ground)for 6 weeks respectively.Before and after training,an infrared high-speed motion capture system(Motion Analysis Raptor-4)was used to capture the motion of the subjects in one CMJ longitudinal jump(CMJ)and six consecutive CMJ longitudinal jump tests.The threedimensional coordinates of the center of gravity of the human body were obtained through system software,and the relevant kinematic indexes such as the height of the longitudinal jump,the angle of the knee joint and the angular velocity of the knee joint were calculated,and the changes before and after training were compared.Isokinetic muscle strength tester such as ISOMED 2000 was used to test flexors and extensors of bilateral knee joints at 240�/Sand 60�/S respectively,and the changes of peak torque,peak power and average power before and after training were compared.Results: After 6 weeks of training,the rapid expansion and contraction combined training of the two interfaces can significantly improve the height of the subjects' single longitudinal jump(P<0.05;0.5<ES<0.8.After 6 weeks of training,the average continuous vertical jump height of sand group was significantly higher than that of hard group(P<0.05;ES=2.15),showing that bilateral knee joint buffering angular velocity and pedaling angular velocity in sand group are significantly better than those in hard ground group(P<0.05;ES>0.5.The isokinetic muscle strength test results showed that the training effect of sand group was significantly better than that of hard ground group in improving knee joint fast strength(P<0.05),which showed that the relative peak torque and average power of right knee flexor in sand group were significantly higher than that in hard ground group(P<0.05);Both groups of training can significantly improve the maximum strength of the knee joint(P<0.05),which is mainly manifested by the significant increase in the relative peak torque and average power of the flexor and extensor muscles of the right knee joint(P<0.05).the sand group has significant difference in improving the maximum strength of the knee joint on the inferior side(P<0.05).Conclusion: 1.Rapid expansion and contraction combined training at sand interface and hard ground interface can effectively improve the single quick strength of knee joint of healthy male youth.2.Rapid expansion and contraction combined training in the sand interface is more helpful to improve the training effect of continuous rapid strength of knee joint of healthy male youth.3.The effect of rapid expansion and contraction combined training in the sand interface to improve the quick strength and maximum strength of the knee joint on the inferior side is more obvious.