It accelerates from zero to 150 in 0.005 seconds, 1000 times faster than a Formula One car, and compresses to half its size at point of impact. If the racquet is a tennis player’s rifle, the ball is his bullet.
But is tennis shooting itself in the foot by using too many different types of balls? The ITF approved over 200 different varieties for play this year, and the industry is currently worth about $300-million. Last week, however, the Sony Ericsson WTA Tour announced that all fall events from 2007 onwards will utilize the same type of ball, following the emergence of “new data drawing a link between player health and frequent change in surface and ball type.” On the very same day, the ATP announced a renewal of its deal with HEAD/Penn Racquet Sports, meaning that all Masters Series events will continue to use the same ball.
To many fans, a tennis ball is just a tennis ball: it’s yellow, it’s bouncy and it loses its pressure over time. But things are little more complicated than that. A ball’s playing characteristics are determined by the way it’s made, explained Dr. Stuart Miller, head of the ITF’s technical department.
“We test them for four things: size, mass, stiffness and bounce,” said Miller. “That governs all the playing characteristics of the ball – for example, how fast it will come off the strings and how high it will bounce. The range of specifications is not that big.
“But different manufacturers will use different formulations, or ‘recipes’ if you like, for the rubber compound that they use. They will have slightly different internal pressures to compensate for the differences in those recipes. They will have different covers with different types and thicknesses of cloth. All those things make up an individual ball.”
At the moment, tournaments themselves choose which ball to use, and rival manufacturers compete to win the endorsement deals. The four Grand Slams all use different balls from three different manufacturers. There can even be variations at the same event. At the U.S. Open, for example, the men and women use a different ball. “They have a men’s ball and a women’s ball at the US Open,” said Luke Jensen, an ESPN commentator and a former doubles Grand Slam champion. “Which is fine... but then you have mixed doubles.
“I’ve played with Mary Pierce and Brenda Schultz-McCarthy where they’ve pushed through to the round of 16 with the women’s ball, then have to play with the men’s ball in mixed doubles, then change back to the women’s ball. To me, that’s ridiculous. It takes time to get used to each ball. It’s very tough to consistently change balls.”
Of course all players, given their differing styles, are going to have a preference for one ball over another. But where does this apparent relationship with injuries come from?
“The simplest explanation would be that a particular brand of ball has a way of generating much higher forces on the racket and making the racket vibrate more, then those forces are transmitted to the players, which may cause them problems,” said Miller.
It’s also possible that the problem lies not so much with which balls are being used, but how many are being used. “It could be that no particular type of ball is bad, but players’ bodies get used to using a particular brand, and when they use another brand they have to get used to it,” said Miller. “Their bodies are expecting one thing then they have to get used to something else. That change means that the forces themselves aren’t a problem, but the body is expecting and is prepared for one thing, but actually gets something else.
“It’s like jumping off a wall in the dark. If you don’t know where the floor is, you’re not able to prepare yourself for the forces that your body is about to encounter.”
When asked to comment on the possible link between injuries and changes in ball types, the ATP’s Laurent Delanney preferred to focus on the fact that the nine Masters Series events all use the same Head ball. But the real issue is not the total number of events using the same ball, but how often players must change between balls as they go from event to event. At present, they may be asked to do so for three straight weeks.
But then the tennis players are creatures of habit, fond of talking about “rhythm”. Using three different balls in three consecutive weeks can only upset their tempo. Are balls really to blame?
One thing’s for sure: the players are unanimous in their desire to change balls less frequently – and at some point the men may just get their wish. “To go to 100 percent Head balls is something we would not rule out,” said Delanney.
There are also some who see other factors as a much more significant source of injuries. As a hitting partner and occasional coach to WTA players, Jason Fransen has struck his fair share of balls. He’s convinced there is no biomechanical link between ball changes and injuries – only a mental one.
“It’s nonsense,” he said, matter-of-factly. “I’ve played with dead balls, fresh balls, and I’ve even played with the extra large rally ball by Wilson. As long as you use good technique, there will be no problems with your health. If you do swing improperly, then the different balls, especially the heavy ones, will most likely exacerbate any problems. But pros should not fall into this category.
“I think that the real problem is that players are pushing their bodies as far as they possibly can go. Every single day they are running, practicing, hitting the gym, playing their match, then going back to the gym. The body is going to wear out at its weakest links. Read: ankles, wrists, shoulders and knees.
“An even more important factor is stress. Tennis is one of the most stressful sports. It’s a proven fact that being stressed out can leave physical pain in the body. If you look at players with back pain, they are often the ones that also have trouble closing out tight matches. They might think that balls are the problem, and that just creates extra stress.”
So, a load of old balls? Time will tell. “We’re only just starting to look at this from a research point of view, to identify if there is something in the balls per se that is making them generate different forces through the racket and into the players’ arms,” said Miller.