The Influence Of Different Heights And Distances Of Drop On The Biomechanics Characteristics Of The Lower Limbs In Depth-long-jump

Research purposes: firstly,to study the influence of different heights and distances of drop on the biomechanics characteristics of the lower limbs in depth-Long-jump.Secondly,to analyze whether there is reciprocal effect between the heights and distances of drop.The use of depth-long-jump for coaches and athletes can improve lower extremity explosive ability in vertical and horizontal direction,which provides theoretical references for coaches and athletes.Research method: Perform depth-long-jump with different combinations of drop height(40cm,60 cm,80cm)and drop distance(30%,70%,110%)of lower extremity length)for 12 male college students who have passed the maximum strength and fast strength tests and have experienced deep jump training.A three-dimensional force plate and an 8-lens infrared high-speed motion capture system are used to synchronously collect kinematic and dynamic data.The repeated measurement two-factor analysis of variance method was used,and the subsequent test method adopted the LSD method.The significance standard for statistical analysis was set at P <0.05.Results: The reciprocal effect between the heights and distances of drop on all indicators were not significant(P> 0.05).At different heights of drop,there is a tendency to increase as the fall height(P < 0.05)in the vertical displacement of the center of gravity in the buffer stage,the horizontal displacement of the center of gravity front and back in the landing phase,the amount of hip,knee and ankle angle changes in the buffer stage,the angle of the ankle landing time,the angle of the hip and knee off the ground,the average angular velocity of the hip,knee and ankle joints in the buffer stage,the relative peak force and the arrival time in the buffer stage(vertical direction).There is a tendency to decrease as the drop height increases(P <0.05)in the angle of the hip and knee at landing time,the angle of the ankle off the ground,the amount of change in the angle of the hip and ankle during the pedal and stretch,and the average angular velocity of the hip and knee and ankle during the pedal and stretch.At different distances of drop,there is a tendency to decrease with the increase of the falling distance(P <0.05)in vertical center of gravity displacement during the pedal and stretch,the horizontal displacement of the center of gravity front and back the landing phase,the angle of the hip and knee at the moment of landing time,knee angle of maximum flexion,the amount of knee angle changes during the pedal and stretch,the average angular velocity of the knee joint during the buffer stage,and relative peak force during the buffer stage(vertical direction),relative peak force and time of arrival during the pedal and stretch(front and back of horizontal direction),distance of long jump for depth-long-jump,and rate of force development of peak force during the pedal and stretch(vertical and front and back of horizontal direction).There is a tendency to decrease as the falling distance increases(P <0.05),the angle of the ankle landing time,the amount of hip,and ankle angle changes in the buffer stage,the buffer time of knee and hip joint,the average angular velocity of the ankle joint in the buffer stage,the arrival time of relative peak force in the buffer stage(vertical direction).Conclusions and suggestions:1.The height of drop and distance of drop are important factors that affect the intensity and effect of depth-long-jump training,but they do not have interaction effect.2.In depth-long-jump,the height of drop of 40 cm is better than that of 60 cm and80cm for the development of explosive force of lower limbs.3.During the buffer stage of depth-Long-jump,the main buffering of the ankle and hip joint are the best when the distance of drop is 30% of the lower limb length;the main buffering of knee joint is the best when the height of drop is 110% of the lower extremity length.4.In depth-long-jump,when the falling distance is 110% of the length of the lower limbs,the effect of improving the explosive force in vertical and horizontal direction is better than that in 70% and 30% of the lower limbs.5.In depth-long-jump,when the falling distance is 110% of the length of the lower limbs,the effect of improving the maximum force effect of push and stretch is better than that in 70% and 30% of the lower limbs.When applying depth-long-jump in training,the coach should choose height of drop or distance of drop that according to the characteristics of different projects,such as motion pattern,power mechanism,and direction of movement,so as to better improve athlete’s lower extremity power and maximum strength for vertical and front and back of horizontal direction.