International Tennis Federation Research Articles

Mechanism of Racket Spin Performance in Tennis(Spin Performance Improvement by Lubrication of String Intersections with Super High Speed Video Analysis)

Players often say that some strings provide a better grip and more spin than others, but ball spin did not depend on string type, gauge or tension in the past laboratory experiment. There was no research work on the spin to uncover what is really happening during actual tennis impact owing to difficult experiment. This paper made clear the mechanism of top spin and its improvement by lubrication of strings according to the high speed video analysis. It also provided the more detailed explanations of spin behavior by comparison between a lubricant string racket and a famous 'Spaghetti strings racket' which was banned in 1978 by the International Tennis Federation since it used plastic spaghetti tubing over the strings to reduce friction resulting in the excessive spin on the ball. As the main strings stretch and slide side ways more, the ball is given more spin due to restoring force parallel to the string face when the main strings spring back and the ball is released from the strings. Furthermore, it showed that the more spin results in the reduction of shock vibrations of the wrist joint during impact.

Season of birth distribution of elite tennis players

In many competitive sports, the use of a cut-off date for junior competition has been associated with a skewed birth date distribution in junior and senior players. The International Tennis Federation uses a junior competition year that commences on 1 January. The purpose of the current investigation was to describe the birth date distribution of 448 elite senior tennis players and 476 elite junior tennis players. There was a significant season of birth bias among elite senior players (P < 0.001), with 58.9% being born in the first 6 months of the year. There was also a significant season of birth bias among elite junior players (P < 0.001), with 59.5% being born in the first 6 months of the year. This pattern was observed in both male and female players as well as in players from different regions. The results provide evidence that it is the cut-off date for the junior competition year that is responsible for the skewed birth date distribution in tennis rather than regional or climatic factors.

PERFORMANCE MEASUREMENT OF TENNIS EQUIPMENT

Equipment is exerting an increasing influence on the nature of tennis. The International Tennis Federation (ITF) Technical Centre was set up to ensure that the challenge and identity of the game is retained, while not discouraging technological innovation. As the physiological characteristics of the player are not under its control, the Technical Centre must pursue its mission through the understanding and control of equipment. This requires systematic testing to establish its characteristics, and research and development projects to identify methods of measuring those characteristics that are not currently covered by the Rules of Tennis. This paper describes tests, test methods and current research programs that the ITF has devised to measure the performance of tennis equipment. Although tennis balls are currently tested for size, mass, compression and rebound, two further variables are being researched to more fully specify its characteristics: dynamic coefficient of restitution and aerodynamics (lift and drag). The former project has suggested an inverse second-order relationship between coefficient of restitution and impact speed. A racket performance machine is described, which is designed to replicate the impact characteristics of tennis serves, and which will be used to benchmark the performance characteristics of tennis rackets. Initial results demonstrate the relationship between "power" and both impact speed and impact location. Surfaces, too, play an important role in determining ball rebound characteristics. A test that measures the frictional interaction between the ball and surface during impact, which is converted to a measure of surface "space" is described. The results of these projects will allow the ITF, in its role as guardian of the game, to make informed decisions on the rules relating to equipment, and help ensure that tennis retains its identity.

An overview of tennis ball aerodynamics

Tennis ball designs are currently being altered with a view to reducing the service speed. A tennis ball, with a diameter increased by 6.5%, is currently being tested by the International Tennis Federation at major tennis tournaments. This paper considers the aerodynamics of the tennis ball and does not address ball impacts. It investigates the ball behaviour during two flow regimes: the initial, unsteady state after racket impact and the quasi-steady motion after any transient features have died away. It is concluded that the transient stage in the development of the ball’s flow regime can be considered negligible, affecting at most the first 3% of its trajectory and altering the initial velocity by less than 1%. Existing drag coefficient data is considered. Cd is 0.55 for a standard tennis ball during serve with no spin (200 000 < Re < 270 000) and this is compared to drag data for spherical models with varying surface irregularities. Further work is identified.

Anyone for tennis?

The Independent [1], prior to the 1996 Wimbledon tournament, carried a story to the effect that Tennis had a problem. Rackets were getting longer and, so the International Tennis Federation (ITF) claimed, rallies were getting shorter as the serve dominated. The story provided some surprising figures. The current limit to the length of a racket is 32 inches, but the longer rackets which are the cause of the problem are 29 inches, 2 inches longer than the standard racket. The article claimed that such rackets 'give players up to 14 per cent more power than standard models'. The article went further,‘Michael Chang of the United States, placed fourth in the world, has been using a 29 in. racquet (sic) since 1994, and says it has been key in raising his ranking.’ [1]

Material Matters: Performance Standards Governing New Materials for Sports

“With a lighter but stiffer shaft and heavier clubhead the ball goes farther. Easier,” claims a 1975 advertisement for Shakespeare graphite irons. New materials such as graphite, boron, and titanium, have made sports equipment stronger yet lighter and thus more powerful. For athletes, sports have become, as the ad stated, easier. Serves over one hundred miles per hour are commonplace on the professional tennis tour, and athletes such as Tiger Woods are making par five golf holes obsolete. Sports organizations do not, however, always embrace these innovations that facilitate play. Major League Baseball retains its traditional mandate requiring only wood bats, the International Tennis Federation prohibited double strung tennis rackets, and the United States Golf Association banned asymmetrically dimpled golf balls. These technology regulations emerged to prevent the sport from becoming “easier,” protecting sport integrity.