I'm no expert on gymnastics. Or gold medals, for that matter.

But I do know that every healthy, normal 14-year-old girl I ever knew wished she was 21 and looked like Cheryl Ladd, one of Charlie's Angels. She wanted to be a C-cup. She wanted to fill out a bikini, and look as if she were poured into her jeans. She didn't want to go through life looking like a flyweight prize-fighter in drag. Only Panamanian jockeys don't want to flesh out.

Which is why medical science is perplexed by the number of European girl gymnasts who seem to have reversed the normal ripening process. They are the only human beings this side of Ponce de Leon who seem on their way from grave to cradle.

The horror story is that some of their countries' test-tube wizards may have found a way to delay or stop onset of puberty.

If that sounds like one of those death-camp experiments, a Dr. Josef Mengele specialty, "The Boys From the Balkans," it is too distressing to be a part of sports.

Gymnastics has become one of the glamor sports of the Olympics. It rivals figure skating for beauty and pageantry. It's a little like watching the Ziegfeld Girls with scorekeeping. They are gradually ruling out those perfunctory "compulsory" figures in favor of the more creative balance beam and uneven parallel bars routines so stunning in form and grace that the Romanian girl gymnasts stopped the show 14 times for standing ovations at the Montreal Games and every magazine in the country had Nadia Comaneci on its cover.

I am happy to report that Nadia is filling out handsomely these days, much to the distress of her coaches, but the delight of the boys from Bucharest. If she's not yet ready to star in her own jiggle show, neither does she look like the boy next door any more. Nadia may do for gymnastic floor shows what Sonia Henie did for ice skating - put it on Broadway and in the Orpheum.

David O. Selznick once vetoed Katharine Hepburn for the part of Scarlett O'Hara because, he said, he "couldn't imagine Clark Gable running around panting after her for nine reels." To be perfectly honest about it, neither could anyone picture Comaneci in her heyday when she was 4-11 and 85 pounds - and 60% of that was eyes. She won seven "perfect scores at Montreal, to the plaudits of the whole world.

Frank Bare, executive director of the U.S. Gymnastic Federation and the czar of the sport in this part of the world, reports that interest as the result of Comaneci is burgeoning. "There were 45,000 gymnasts here in 1970. Last year, there were 400,000. But that's nothing. There are 14 million in the rest of the world. In some Iron Curtain countries, one out of five is into gymnastics."

The U.S. hasn't won any gold medals in Olympic gymnastics since the days when Indian clubs were part of the competition. But our showing in the Strasbourg World Cup, where we won two gold medals, is encouraging.

But, if winning a gold medal means going through life looking like a stick with legs and never getting asked to dance, why, I'd prefer somebody who's been through puberty, all right - like Liz Taylor.