Studends Of Professional Badminton Athletes Hitting The Backcourt Lofty Forehand Ball Technique Kinematics Analysis

Objective:This research is doing the kinematic analysis with five excellent malebadminton players in college about their technique of the backcourt forehand clear.The aim is to use the biomechanics and theory of sports, to analyze the index andparameter of human body during moving fetch bit/backswing and swing the racket.Finally it will show the kinematics characteristic of backcourt forehand clear, whichwould provide the theoretical foundation for sportsman’s technique inprovement, andalso provide the data&scientific foundations for the tranings and the matches.Method: In the research I used two cameras with high definition SONY1080i, ofwhich the photographing frequency is50HZ. The subjects are the imitatingcompetitions of five male players(all of them ae right handed) of Capital College ofPhysical Education.Among all I choose a good and complete ball-hitting as theresearch video, then i use the American Ariel analysis system to analyze it.Result:1.The moving time is0.916s during the moving fetch bit, the moving distanceof the left foot and the right foot is1.775m、2.177m, and their speed is1.954m/s、2.366m/s.Before they hit the ball,during the preparation posture, the angles ofshoulder/elbow/wrist are separately64.813°、57.703°、157.799°；the angles of theleft and right hips are165.33°and154.239°;the angles of the two knees are143.506°and105.646°.2.During the backswing period, the angle of shoulder is gradually increased; the angleof elbow is firstly increased and then decresed and finally increased; the angle of wristis slightly changed.The angle of left hip is greater then the right hip, the left hip getsmaller, while the right hip is slightly changed, the left knee joint is bigger than theright one, the angle of both is increased.The body twist angles of Gong Chi/NiuMengnan/Tian Weizheng/Yu le/Zhang Junbao are12.641°、18.467°、25.685°、13.529°、7.789°respectively.3.During the period of swing the racket, for these five players, the time is0.0064s,thedistance is1.684m, the speed is26.747m/s: the fast speed sequence of the right upperlibms is shoulder-elbow-wrist-hand-racket.The body twist angle of the five players is2.857°、8.670°、2.236°、4.813°、0.707°respectively.4.During hitting the ball,the angle of shoulder/elbow and twist is103.825、147.534and161.207; while angles of the left and right hips/knees and ankles are153.728°&158.005°；108.628°&130.919°；92.832°&86.202°Conclusions:1.During the movement the five players all used the Cross behind threestep shifts. The preparation posture before hitting the ball is good, however their center of body is not steady enough, moving up and down.2.In the period of swing the racket,the five excellent players swang the racketaccording to the “exceed the machine” priciple, but their arms did not fully swang.Their angle of body twist are big, thus they formed“the left shoulder is behind,theright hit is in the front”.This is helpful for increasing the strength and speed.3.When hitting the ball, the body joints of the five players orderly speeded up andbraked, their hittings were in accordence with the “wipping principle”.The body twistangle is small, and formed the posture of “right shoulder in the front and right hipbackward”, which is helpful for reverse movement.4.When hitting the ball, for the lower limb, the hips/knees/ankles were not sufficientlymoved, so the strenth of the lower limb can be well used.