| The forehand is a shot approach that is more and more using in basic technology of the tennis. The use frequency of forehand is 70% of the total game according to a statistical analysis. Top-spin is strong rotation, big forward momentum, high bouncing, jump far, high stability, increase the distance and the difficulty of returning to hit ball, causing opponents passive and difficulties, is a powerful weapons that drive (ball in Tennis and breaking the volley in the backcourt. Flat stroke is a strength and rebound, it hardly be rotation, while the effect of air resistance will produce flowing, that has a very strong offensive power ,known usually as the "wave ball" by people. Top-spin and flat stroke are different, each with their advantages and disadvantages, top-spin stuady far more than flat stroke, A comparative study wasn't exercised between flat stroke and top-spin.This article used biomechanical methods and measurement means, the wireless telemetry electromyography test (1000Hz) (Finland MEGA), combined with high-speed photography (120frames/s) and other instruments, tracing the forehand about six excellent male tennis subjects on the live. Analyzed the major muscle activity by the specialized software (EMG) and analysis system using high speed photography (APAS) for resolution of the player movement, access to Kinematic Parameters and muscle discharge characteristics about tennis forehand and top-spin, combined with quantitative and qualitative analysis to clarify the basic principles of its action, studied on technique comparative of top-spin and flat stroke, explored the characteristics and laws and revealed further its muscle contraction, as well as the existence of the different ,discussed two points of swing sports teaching and training key points, The study of this paper provides the theoretical and experiential foundations for the improvement and rationalization of a better grasp of top-spin and flat stroke in teaching and training techniquesAnalyzed the original map of EMG and to obtain the order and the integral value of time of activity about each muscle, come to obtained the angle of each joint and the maximum speed of hitting point and major joints about wrist joints,elbow joint and so on through the analysis of high-speed camera shots.We can obtain the following conclusions after analyzing the results of the study: EMG analysis on tennis serve has discovered that deltoid and trapezius send out strength at fist and keep longer duration than other muscles and contribute the most strength.(1) In the swing , the trapezius, biceps first began to discharge, and longer duration, pectoralis major, and began to discharge later in the gluteus maximus, and the relatively short duration, radial muscle, brachial biceps and trapezius EMG integral values of the maximum, thus indicates that the process of hitting trapezius and biceps muscles are the main force..(2) Swing tennis forehand spin moment, making the angle between the ground surface and 35.4°, knee angle of 153.5°, the size of arm angle 104.7°, the angle of arm and trunk 37.6°, combined with structural features of the human body, the more favorable attitude, that can increase swing speed, without losing the pedal switch to the explosive. Flat surface and the ball hit the ground instantly making the basic angle perpendicular to the ground, the knee angle of 159.6°, the size of arm angle 120.7°, the angle of arm and trunk 57.6°, so the control surface is conducive to beat, hit rate fast flat shots.(3) Two major joint and the ball is the most significant differences exist speed, when all joints and hold spin faster than hit points when flat faster, Want to hit powerful topspin must accelerate the wrist and forearm hood and body thrust in turn. And when the ball hit flat hood is not obvious, wrist and forearm basic beat in a straight line, ball control in the knee kneel to the height, or explosive, increase.(4) According to the process of hitting, maximum speed of major joints results in chronological order: Reflect the force sequence ankle - knee - hip - shoulder - elbow - wrist, force is characterized by leg kicking - trunk tilt– Stretch shoulder– Stretch elbow - forearm internal rotation - rotating the upper arm - wrist flexion.Recommendation:(1) We strengthened forehand strength training in the usual, enhance trapezius, biceps, deltoid and quadriceps maximum power, speed strength, reactive strength training, but also to strengthen the wrist around the flexor, extensor grip strength training, and back external oblique, latissimus dorsi muscle training.(2) Through the kinematic analysis in the process of hitting, controlling the racket face and the ground angle, knee angle, wrist angle, size, arm angle and the high ball, is difference between powerful topspin and flat. Speed up the rotation speed of the major joints at the same time.(3) We must make full use of the coordination chain of the human body, that is head and shoulders, upper body, hip (waist), four-part leg coordination and orderly force, to force the body seamlessly passed to the racket hits the ball in the right strike.
|
PDF Full Text Request