Billie Jean King beat Bobby Riggs at the Houston Astrodome in 1973, in front of 30,472 spectators and a television audience of millions. Coming on the heels of the passage of Title 9 of the Education Amendments Act, this sports event opened the psychological floodgates for women's sports.

Three years before that match, the highest-paid female professional athletes were golfers. Who would have guessed then that, by 1980, 16-year-old girls could earn $750,000 a year playing tennis? Or that a franchise in the Women's Basketball League would cost $1 million (the owners of the Chicago Hustle recently turned down a $1 million offer? Or that some large corporations would orient their television ad campaigns around women athletes (Nancy Lopez, Chris Evert Lloyd, the Young twins, Susy Chaffee)?

Among team sports, basketball has been the major recipient of this new interest in women and sports at the pro level. Talent is developing so fast that this year's first-round draft choices for the WBL most likely will have to struggle to make their teams next year.

Three factors have helped the WBL tremendously:

Regional television coverage. New technology has opened up unexplored opportunities for sports broadcasting. In Chicago, for example, the WBL's Hustle outdraws the Chicago Black Hawks on local television.

Crowd demographics. It appears that many 9-to 16-year-old girls come out to watch the games. But being naturally more protective of a daughter, daddy comes along, too. Some times he comes for protection, but more often than not it's because the game is another sports event a father can share with a daughter.

While women's pro soccer waits in the wings for the right opening women's pro golf is taking off. This year is the 30th anniversary of the Ladies' Professional Golf Association, and if last year's record-breaking crowds are any indication, 1980 promises to be ever better. Thanks to increased prize money, competition has become fierce throughout the entire field.

Of course the "names" are still around -- Sandra Haynie, Sandra Palmer, Sandra Post, Jane Blalock and Judy Rankin. But the game's biggest draw now is Nancy Lopez, whose fan appeal reminds people of Palmer.

But the most important changes have occurred in the thinking of the women athletes themselves and the crowds they play for. In the sports training center that I use in New York, it is now common to see a professional athlete like Billie Jean King and some female corporate executive side by side, straining and sweating while lifting weights. That would have been considered an activity unfit for a woman 15 years ago.

Last September at the U.S. Open tennis tournament, I was talking to Tracy Austin about weight training. "I don't want all those muscles like Martina (Navratilova)," she told me. When I assured her that the purpose was to build strength, not muscles, she still was hesitant.

But once the coaches of these exceptional female athletes are turned on to the knowledge derived from the study of exercise physiology, misconceptions like Austin's will disappear.

Postive crowd reaction also has played an enormous role in helping young women athletes "feel at home" with competition. For instance, in junior soccer leagues around the country, up to the age of 13, boys and girls play on the same teams. Young girls are encouraged to "mix it up" with their male counterparts. The cheering that results from spectators and teammates is a powerful and positive reinforcement that they "belong."

As these girls get older, they and their parents will no longer tolerate a slow, gradual adherence to Title 9. Almost 560,000 high school girls play varsity basketball at present, and by 1982 more than 1,000 colleges and universities will field women's varsity basketball teams. They are lucky; the WBL will probably he along to soak up the best of the lot.

Women's pro tennis and golf are doing quite well. And when the likes of a Tracy Austin realizes that weight training will make her even faster, stronger, and quicker -- without adding muscles -- she too may win 20 Wimbledon titles, like Billie Jean King did. If she doesn't take advantage of the training, she probably will not eclipse King.