By Matthew Stock
Engineers at the University of Sheffield have teamed up with the International Tennis Federation (ITF) to measure the effects of friction between tennis court surfaces and footwear in a bid to ensure the world's top players can play their natural game and slide in a controlled manner, with a reduced risk of injury.
Sliding is a key skill on clay courts, mastered by the likes of one-time 'King of Clay' Rafael Nadal, who enjoyed years of success in the French Open at Roland Garros. But the fast pace of the modern tennis game means that top players are also using slipping and sliding as a technique to move more quickly around grass and hard surface courts to reach the ball.
"In all sports athletes tend to push the interactions to a greater degree. And in elite tennis we're seeing that more players are sliding on hard courts than they used to. So the kind of movements that they're carrying out on hard courts would be something that you might have seen on clay courts before," said Dr Matt Carré from the Department of Mechanical Engineering.
The increase in sliding among top players could be a natural reaction to more powerful racket technology, according to mechanical engineering PhD student Daniel Ura.
"The speed of the game has increased a lot because the players are serving faster than years before; it could be because of the materials of the racquets or could be the strings as well. But I think it's a necessity of the players to reach the ball faster," Ura told Reuters.
Working in collaboration with the International Tennis Federation (ITF), the world governing body of tennis, the researchers have conducted experiments to measure the amount of friction between different playing surfaces and shoes. Carré said their laboratory testing rig mechanically replicates the friction between the player, the shoe and the surface.
This includes parameters like the surface type, player force, sliding shoe orientation, outsole temperature and speed during critical player movements, he said.
"The end goal is to actually develop a system that allows us to better understand tennis courts and how they perform and to monitor the tennis courts. In order to do that we need to understand a number of parameters including; how the shoe changes, how the properties of the shoe affect that interaction, how the properties of the tennis courts affect that, and also other factors like temperature and the actual players loading themselves, so how they slide or move around on the courts," he said.
Their aim is to develop a portable hand-held device that could measure the friction of any tennis court and allow players and coaches to adjust their game plan. This could lead to a 'sliding scale' for surfaces that grades them according to their propensity for sliding.
While it will help the ITF more easily regulate tennis courts around the world, the research could also aid tennis shoe and surface manufacturers in designing new footwear and tennis courts to maximize a professional player's ability to control their sliding.
Ura likened it to Formula 1 motor racing, where the choice of car tire is crucial, depending on the condition of the track.
"I think it will become more like a Formula 1 race probably, when depending on the weather conditions or depending - in this case - on the surface conditions, I think the shoes are going to play an important role during a match. So I think that's probably the future of the shoes, they're going to start to customize them according to the surface properties," he said.
"So I think when we're able to find the optimum friction or the optimum parameters between the shoes and the surfaces, then the shoe and the surface manufacturers are going to be very interested to try to improve their shoes (and) their surfaces to get the best performance."