Motion Analysis Of Two-handed Backhand Batting Of Top Spin In Tennis

There are only 2 athletes using single-handed backhand batting in the top ten athletes of ATP, the other 8 athletes using two-handed backhand batting. In two-handed backhand batting technology motion, top spin ball is more reliable and stable with high deterrent. Therefore, it has very great significance of studying kinematic and physiological characteristics of two-handed backhand batting top spin ball detailedly and in-depth to train athletes to grasp scientific and reasonable technology motion and improve the technical ability of two-handed backhand batting top spin ball.This research explored this by taking 6 national tennis athletes of Grade II as experimental subjects, and adopted the three-dimensional camera shooting technology and the surface electromyography (sEMG) technology to test in step. Tested motion is base line straight line direction two-handed backhand batting top spin, and it was simultaneously tested that muscle electrical activity of 12 pieces of muscle such as posterior segment of gastrocnemius, musculi rectus femoris, external oblique muscle of abdomen and so on. And then processed the data of 23 points on human body and bat by Apas System software, integrated the discharge of 12 pieces tested muscle by making use of the Megawin software, calculated the data by making use of statistical methods, and obtained the results including speed, angle, angular velocity, time, and integrated EMG etc.Statistical analysis of the data shows:(1) In the end of backswing, the speed of shoulder joint point reaches the fastest, and the angle between shoulder and hip is 43.936°.(2) In the instant of batting, every arthrosis movement of the left limb takes the hip joint as the critical point. The left upper limb motion should be called the kind motion of whipping, but the left lower limb motion should be called the kind motion of upside down whipping. The distance of z-axis direction (the vertical direction of barycentre of body) is 0.118 m, the angle between shoulder and hip is 18.370°. The angle between the face of racket and the floor should be controlled in 57°～77°, the angle of racket head should be controlled in 19°～35°.(3) In the stage of the backswing, the first five pieces of muscle with the strongest activities are the left rectus femoris→the rear of right gastrocnemius→the left brachioradialis→the rear of left gastrocnemius→the right rectus femoris. In the stage of front swing and follow-through of batting, the first five pieces of muscle with the strongest activities are the anterior of left deltoid muscle→the left brachioradialis→the rear of left deltoid muscle→the left biceps brachii→the rear of left gastrocnemius.(4) In the continuous discharge process of batting, the order of 12 pieces of muscle continuous discharge is the left rectus femoris→the rear of left gastrocnemius →the right rectus femoris→the anterior of left deltoid muscle→the rear of right gastrocnemius→the posterior of right deltoid→the left biceps brachii→the left pectoralis major→the left brachioradialis→the right obliquus externus abdominis muscle→the right latissimus dorsi→the left obliquus externus abdominis muscle.The conclusions are as follows:(1) In the instant of batting, every arthrosis movement of the left limb takes the hip joint as the critical point. The left upper limb motion should be called the kind motion of whipping, but the left lower limb motion should be called the kind motion of upside down whipping.(2) In the motion of wo-handed backhand batting of top spin, top spin depends on the effective combination of the angle between the face of racket and the floor and the angle of racket head, it is a negative relationship between the angle between the face of racket and the floor and the angle of racket head. The barycentre of body should be kept at the height of 0.118m above the tennis ball and perpendicular to the ground.(3) In the process of wo-handed backhand batting of top spin, the angle between shoulder and hip should be controlled in 43.936°behind the hip joint in the end of backswing, and the angle between shoulder and hip should be controlled in 18.370°in the front of the hip joint in the instant of batting. The coordination and contractility of latissimus dorsi and obliquus externus abdominis muscle should be improved, that is help to pose the best angle between shoulder and hip.(4) In the technology motion of two-handed backhand batting of top spin, there are some mainwork muscles which are the left rectus femoris, the rear of left gastrocnemius, the left brachioradialis, the rear of right gastrocnemius, the right rectus femoris, the anterior of left deltoid muscle, the anterior of right deltoid muscle and the left biceps brachii.