Professional tennis players call it "the Luxilon shot," and, apparently, you can hear it coming. The ball crosses the net hissing and spitting like some enraged tropical insect. Its most lethal element is its topspin, which can dip the ball crosscourt in short angles so extreme that "the game has gone from linear to parabolic," as ex-pro turned coach Scott McCain recently put it. "It's like ping-pong out there."
The Luxilon shot can be traced back to 1997, when Gustavo Kuerten, a gangly, low-ranked Brazilian player, decided to string his racket with a co-polymer monofilament designed by Luxilon Industries, a small Belgian company specializing in medical sutures and bra straps (it still makes both). Kuerten confounded opponents with his aggressive, dipping shots, winning three French Open Championships and reaching number one. He credited Luxilon for a crucial role in his unlikely ascent. (See pictures of Wimbledon.)
Today, natural gut strings the strands of sterilized cow entrails once used by most professionals have all but disappeared from pro tennis. At this year's French Open beginning May 24, 65% of men and 45% of women will use a Luxilon string, and almost all those who don't will use an imitation. This despite the fact that the family-owned company based in Antwerp refuses to pay top players to use its products and requires most to buy the string almost unheard of in the freebie-filled world of professional tennis.
But is the "Luxilon shot" all down to Luxilon string? In a 2006 article titled "The Inch that Changed Tennis Forever," Rod Cross, a physics professor at the University of Sydney, argued that the innovation in equipment that transformed topspin from a looping, defensive shot into a dive-bombing, offensive play actually happened in the late 1970s, when equipment makers widened the heads of professional rackets from nine inches to 10 (they also dropped wood for metal and eventually graphite). The extra inch allowed players to tilt the racket forward and swing from low to high without worrying about clipping the edge of the frame when brushing up on the ball.
According to Cross, nothing much has changed since that innovation; it's only in the last 10 years that players have developed the physique and technique to take advantage of the extra width by whipping the racket up in a motion that generates about five times more spin than the ground strokes players were hitting in the 1970s. "Players were given an inch in the 1970s and they took a mile," he says.
Pinpointing the role equipment has played in tennis's evolution can be tricky, however. Conventional wisdom once held that more powerful racket frames led to the hard-serving power game of the late '90s. But a 1997 test by Tennis Magazine found that 6 ft. 5 in. (1.96 m) Australian Mark Philippoussis served at an average speed of 124 m.p.h. (200 km/h) with his own graphite racket, and an only slightly slower 122 m.p.h. (196 km/h) with a classic wooden racket.
Polyester monofilament strings do generate "slightly more" spin than older generation strings, according to the International Tennis Federation (ITF), which started testing the playing characteristics of strings three years ago, but ITF head of science Stuart Miller says he's not sure why. One theory is that far from "biting" the ball, as many players describe it, the strings are "slippery" when the ball pulls the strings out of their gridded alignment, they snap back quickly, propelling the ball's rotation. (See pictures of Pete Sampras.)
Yet even as strings offer greater potential for spin, players need technique to fulfill that potential. As Miller says, "the most important factor in the generation of spin is racket speed." Research by Cross at the University of Sydney has shown that pro tennis players have much less feel for strings than they think, and tend to overestimate their importance. A study published last year found that 90% of professionals could not feel a 6 lb. (2.7 kg) difference in the tension of strings in two different frames even though most professionals insist on exacting string specifications for their matches.
Players who use Luxilon string say it feels "stiff" and "dead" on impact. But Luxilon general manager Nico van Malderen says that internal testing has shown the string is actually more powerful than the average. So it's possible that players developed aggressive topspin strokes with Luxilon because they felt they needed to swing harder to generate the same pace. As former world No. 1 Jim Courier says, "Technology has been the catalyst, but my guess is that if you forced all players to go back to technology from 1950 they would play much more aggressively than previous generations. The new style is working for them." Whatever the exact interplay of man and equipment may be, it has allowed fans to witness a thrilling revolution.