A KINEMATIC ANALYSIS OF A TOP 10 WTA TENNIS PLAYER’S FIRST SERVE

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The purpose of this study was to provide valuable information of the tennis serve, through a three-dimensional (3D) cinematographic analysis of Li Na’s flat serve. Two high-speed cameras operating at 200Hz placed around the baseline recorded her flat service motion. The direct linear transformation (DLT) method was used. The ball was hit at a distance of 1.11 m below a peak ball toss height of 3.65 m. In backswing, the minimum knee flexion angle was about 110°. The lowest point recorded by the racket head was about 0.21 m lower than the height of the body center of gravity during the early drive phase. The velocity of the racket head was 38.2 m/s at impact and the height of the impact point was 2.5 m which was 1.48 times the height of her body. Like other elite tennis players in the world, Li Na has her own tennis strokes and swing style.