PLAYERS SEEK HIGH-TECH EDGE

WHEN teenagers Monica Seles and Arantxa Sanchez Vicario slugged it out for the title at last weekend's French Open tennis tournament, they had something else in common besides being finalists and past champions. They both used ``wide body'' racquets, the latest development in tennis technology. The so-called wide-bodies - broader in the beam yet lighter than their predecessors - are adding new power to the game. Popular first with recreational players, they are slowly winning over the top pros as well.

``I think it's only a matter of time'' before the top players in men's tennis use the new technology too, says Rudrapatna Ramnath, a professor of mechanical engineering at the Massachusetts Institute of Technology.

Dr. Ramnath should know. For more than a decade, he's been testing tennis racquet designs and reporting his findings in World Tennis magazine.

Each year he takes 60 or 70 new racquets, supplied by the manufacturers, into his laboratory to study how they react. Using several kinds of tests he measures things like their weight and weight distribution, size of the hitting area, balance point, stiffness, and vibration dampening ability. He also determines the size and shape of the ``sweet spot,'' the area of the strings where a stroke will feel good to the player and produce the hardest shots, through tests he developed himself.

Wooden racquets were the standard from tennis's earliest days in the 19th century until the 1960s. Wood was resilient and reliable, if not too durable.

In the late 1960s, rising young pros like Jimmy Connors began to popularize steel- and later aluminum-framed racquets. In 1976, tennis innovator Howard Head revolutionized racquet technology with his oversized Prince racquets, which nearly doubled the size of the hitting surface and offered improved power and control. New materials - graphite, boron, magnesium, titanium, Kevlar - enabled racquets to balloon in size while actually losing weight, thus increasing power and maneuverability .

In 1987 the first wide-body racquets came on the market. Their wider shafts, often made of fiberglass reinforced with more exotic materials, provide greater stiffness and even more power.

More than hitting power has skyrocketed. So have prices. The wooden Jack Kramer autograph model popular in the '60s and early '70s might have sold for $35 then; today's wide-bodies start around $100 and go up to about $300.

RAMNATH, an avid player who still competes in amateur tournaments, says choosing a racquet is still largely a matter of personal preference. He and most experts agree that players should try several racquets and buy the one that feels most comfortable.

Ramnath adds that his testing enables players to compare racquets based on standardized test results and narrow their choices to a manageable number out of the whole bewildering array on the market.

Players can also match racquet characteristics to their styles of play. Inexperienced players, for example, may be looking for a racquet that adds power to their game, while top male players, who generate plenty of power, may seek a model that gives them more control. Baseline bashers and net-rushing serve-and-volley players need different types of racquets as well.

Despite their higher costs, the new high-tech frames are selling well, helping to bring back a slumping tennis equipment industry. Some 8.4 million racquets were sold at the height of the tennis boom in 1978, but this number dropped to a low of 2.2 million sold in 1985, according to the American Tennis Industry Association. By last year, sales had climbed back to just over 4 million units.

Ramnath isn't sure where racquet technology will head next, but he sees a period of ``gradual fine-tuning'' in areas such as weight distribution and possibly in stringing tensions and spacing. At one time, the International Tennis Federation had nearly no rules governing the shape, size, or construction of racquets. But in recent years it has introduced specifications to ensure that the technological revolution doesn't change the basic nature of the game.

That may mean that racquet development will slow down in the next few years. If so, it won't bother Dr. Ramnath: He's just begun testing golf clubs for a leading golf magazine.