| Research purposes: In the highly antagonistic tennis sport,attack and defense are complementary to each other.The backhand cutting ball,as a conversion technology between attack and defense,has been paid more and more attention in today’s tennis match.In this paper,second-level athletes and tennis students are taken as the research objects.Through testing the joints of the upper and lower limbs and the main muscles of the body in the process of hitting the backhand cutting ball,and combining with the multi-disciplinary knowledge of sports biomechanics,sports anatomy and so on,the analysis is carried out.This paper explores the kinematic characteristics and muscle power generation characteristics of the tennis backhand cutting ball in the stage of leading the racket,hitting the ball and following the swing,so as to provide more scientific and targeted technical theoretical support for the coaches in the teaching and training of sports majors and tennis majors.Method: In this paper,8 second-level tennis players and 8 professional tennis students from Xi ’an Institute of Physical Education are taken as the research objects,and the action of the subjects hitting the backhand cutting ball is simulated by the way of experimental condition control on the tennis court.The Motion information was obtained by 3d high-speed camera（100HZ）and EMG system（1000HZ）synchronous test.Simi Motion analysis software was used to collect the Motion image information through automatic tracking,manual spot filling,low-pass filtering and smoothing to obtain the kinematics data.After processing the collected EMG signals with the Mage Win600 analytical software of the EMG system,the integrated EMG values,root mean square values and other data of the tested muscles were obtained.Excel and SPSS23 were used to conduct statistical collation and independent sample T test for the obtained data.Results:（1）The speed of the left elbow,left wrist,right knee,right hip and right shoulder of the second-level athletes was significantly higher than that of the special tennis students（P<0.05）,and the speed of the right elbow and right wrist was significantly higher than that of the special tennis students（P<0.01）.（2）The right shoulder Angle,right elbow Angle and left shoulder Angle of the second-level athletes at the end of the lead beat were significantly higher than those of the special students（P<0.05）,and the linear speed of the right shoulder on the X axis and the closing speed of the right shoulder of the second-level athletes 0.02 seconds before the end of the lead beat were significantly higher than those of the special tennis students（P<0.05）.（3）At the moment of hitting the ball,the speed of the right hip joint point on the X-axis of the grade II athletes was significantly higher than that of the special students（P<0.05）,the trunk torsion Angle of the grade II athletes was significantly higher than that of the special students（P<0.05）,and the force of the right triceps of the grade II athletes was significantly higher than that of the special students（P<0.05）.（4）At the end of swing,the left knee joint Angle and center of gravity height of the second-level athletes were significantly different from those of the special students（P<0.05）,and the latissimus dorsi muscle of the right side was significantly higher than that of the special students（P<0.05）.Conclusion:（1）In the process of backhand cutting the ball,the power transmission of two level tennis players and tennis students is from bottom to top,but the power transmission efficiency of tennis students is smaller than that of two level tennis players.（2）In the process of leading the racket,the flexes of the right elbow joint of the second-level athlete are larger,which makes the triceps of the humerus exert obvious force in the hitting process.In the process of leading the racket,the integrating EMG value of the right rectus femoris muscle is large.Therefore,judging the leading stage of backhand cutting ball action may mainly rely on the right leg to push the ground to drive the turning leading racket.（3）In the backhand cutting action,the front stability Angle of the second class athlete is less than the back stability Angle,and the center of gravity follows the direction of the stroke.The second-level athletes can make full use of the ground rotation of the lower limbs to drive the hip joint rotation,thus driving the shoulder,elbow and wrist in turn,and the right hip joint at the moment of hitting the ball in the X-axis speed toward the direction of the ball.（4）In the swing stage,the right latissimus dorsi muscle of the second-class athletes contracted and exerted obvious force,and the balance of body posture was maintained by pulling the arm holding the racket. |
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