| Blocking refers to the player blocking the ball hit by the opponent on the net.It is the first line of defense for counterattack and the main means of scoring.The blocking team played a very large part of this score in the game.The key link of the block is the horizontal movement.The cross step is the most frequently used and fastest moving step in the block movement,which has a very important impact on the block effect.Objective: To explore the characteristics of bilateral cross-step movements of male auxiliary attackers of different levels through biomechanical means,analyze the factors that cause differences between different levels,and provide a scientific basis for teaching and training.Participants: 15 outstanding male offensive athletes from Beijing Sports University,Beijing University of Aeronautics and Astronautics,and Capital College of Physical Education were used as test subjects(age 22 ± 2 years,weight 90 ± 11 kg,height 197 ± 2cm,training period 9 ± 4 years).Methods: The two-way cross step(CS)blocking movement was performed on the force plate to obtain dynamic data,and the kinematic data of the athletes was captured by the infrared light spot motion capture system.Results: 1)There is a significant difference in the movement time of the volleyball auxiliary attacker when he crosses the block on both sides in front of the net.The movement time on the right side is significantly shorter than that on the left side.2)In the comparison of different levels,the angle of the hip joint valley value increases with the increase of the level when the left and right movements of the swinging leg are moved;the knee joint valley value decreases with the increase of the level when the right side moves,and the left side moves The knee joint valley value increased with the increase of the level.During the support leg movement phase,the knee joint valley angle decreases as the level increases when the right side moves,and the knee joint valley angle increases as the level increases when the left side moves.During the kick-off phase,the hip joint peak value increases with the level when the left and right sides move.3)In the start-up phase,when swinging on the left side,the peak of the athlete ’s momentum and ground reaction force will increase with the increase of the level,and when supporting legs are moved on both sides,the peak of the athlete’s momentum and the ground reaction force will increase with the increase of the level.In the cushioning stage,the legs build up when the left and right sides move.The peak of the athlete ’s momentum and the ground reaction force increases with the increase of the level,and the middle section of the curve shows the level difference.4)Comparing athletes’ bilateral movements,the knee angle of the knee joint is significantly higher than that of the left when the right movement is performed,and there is a significant difference in hip flexion and extension changes when the left and right movements are performed.Conclusions and suggestions: 1)There is indeed a significant difference in the moving time of the volleyball auxiliary attackers when they cross the block in front of the net.The horizontal movement stage is the link that causes the difference in movement time.The differences in the valley angle of the knee joints,the changes in flexion and extension of the swinging hips,and the forces during the horizontal movements are the reasons for the differences.2)As the level increases,the trough angle of the knee joint of the legs gradually increases when moving to the left,and gradually decreases when moving to the right.3)In training,the athlete should be instructed to swing the hip flexion valley of swing legs at about 130-140 degrees,the knee valley of support legs to be between 85-90 degrees,and the knee flexion of swing legs to be 100.-120 degrees.During the training,more training can improve the athlete’s lower limb muscle cushioning ability and explosive power. |
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