Champion gymnast Ali Blumberg is preparing for her floor exercise.

She frowns a moment, concentrating. She goes up on her toes and poises, her body completely still. Then she bursts onto the mat and in a matter of seconds, tumbles through a series of leaps, handstands and pirouettes, finishing with a double back somersault.

Blumberg, 14, of Potomac, is training for Sunday's U.S. Women's Gymnastics Trials for Israel's 11th Maccabiah Games. The trials begin at 2 p.m. at the Montgomery College gym in Rockville.

Blumberg will have about half a minute to show the judges she is a champion, according to her coach Gary Anderson.

"She's looking at seven years of training, maybe 7,000 hours of work, and it all comes down to 25 seconds," Anderson said, shaking his head.

"It's a lot of pressure. The one who can handle it is the one who usually becomes the victor. You can have all the talent, but still not be a competitor. If you can't handle the pressure -- be able to block everything else out -- you can't get on an international team."

Anderson is confident Blumberg and teammate Stacey Broth, 13, of Gaithersburg, can be international champions. In the Maryland State Gymnastics Championships last weekend, Blumberg placed first in the vault and floor exercise and third all-around in her age division (12 to 14). Broth placed fourth in the parallel bars and seventh all-around in the same division.

Both girls train at the MarVaTeens gymnastics facility in Rockville, which Anderson owns, and both hope to make the five-member women's team that will compete in the Maccabiah Games July 6-16. The games are held every four years and are patterned after the Olympics, with one difference: all the participants are Jewish.

To Blumberg and Broth, who say they have been "best friends" for three years, going to Israel "means everything."

"If I can make it to Israel I'd love it," Blumberg said.

Anderson feels the trials Sunday could bring the girls one step closer to the Olympics. He says Blumberg and Broth are "very likely candidates in 1984. Their timing is excellent. They'll be the right age and have the right experience behind them."

Anderson -- a former All-American gymnast and member of the 1971 U.S. gymnastics team at the Pan-American Games -- says the girls' success depends on their health and whether they can train for the next two years without interruption.

"If they're out for even six months, it will set them back for a year," he said.

Broth already has one handicap -- a disease that keeps her bones from hardening as quickly as they should. She performs in considerable pain, packs her knees in ice after workouts and takes six to eight Bufferin tablets daily. Anderson said her condition is not uncommon among teen-agers and should clear up in six months to a year.

The girls' dedication to gymnastics has meant they have had to sacrifice school activities and social life. Their daily five-hour workouts leave little time for anything else.

Blumberg said her friends at Herbert Hoover Junior High asked her to try out for the cheerleading team, but she had to turn them down. "It's not important to me now," she said.

Broth, who attends Robert Frost Junior High, added, "I guess when we get older, we'll want to make time to date."

Despite the sacrifices, Blumberg and Broth spoke almost in unison about their love of gymnastics.

"It's given us opportunities we wouldn't have had," Broth said, referring to their extensive travel to various competitions throughout the United States and Canada.

"We just love it," Blumberg added.

The two young competitors said they root each other at competitions.

"We'd like to tie for first," Broth said. Blumberg added, "We don't care about beating each other, we just want to keep our friendship together."

The parents of both girls support their commitment to gymnastics. Blumberg's father Charles, an architect with the National Institutes of Health in Bethesda, is head of the MarVaTeens parents group, which raises money for out-of-town travel to competitions. Her mother Ina, a speech pathologist, also helps with the fund-raising.

Broth's stepfather Marvin Guerra, a manufacturer's representative, and her mother Marianne, an editor, say their daughter's discipline "has carried over to her schoolwork" and resulted in a "remarkable change for the better -- despite her long hours in the gym."

Both girls say they want to continue in gymnastics "forever." Or at least, "until we start to get too fat to compete."

Blumberg is 4 feet 9 and weighs 76 pounds.Broth is 4 feet 11 and 82 pounds. They maintain their lithe figures by controlling their urges for chocolate, soda pop and corn chips.

Anderson said the girls' "nearly perfect" gymnast bodies are a factor in their success. "They are both very lean, with a low percentage of body fat. They are very explosive performers because they possess fast-twitch muscle fibers."

He proudly labels them "outstanding. Their best characteristic is that they are motivated. They have a great desire to be champions and international gymnasts. They are willing to push themselves and be pushed," he said.

But while Anderson admits it's "a coach's goal and dream to enter his athletes in the Olympics," winning is not his primary mission.

In addition to training teams, Anderson and his staff teach gymnastics to 900 students, some as young as 2.

"You see that little one?" he asks, pointing to a 3-year-old climbing a ladder in preparation for an 18-foot fall onto foam pillows.

"She's going to master it. She's going to walk away and feel real good about herself." The feather-weight tumbles onto the pillows and jumps up with her arms outstretched, Rocky-style.

The six other local participants in Sunday's event will be Marni Rager, 11, and Stephanie Foxman, 12, of Silver Spring; Amy Berfield, 14, and Janna Jeffries, 13, of Bethesda; Missy Woldoff, 11, and Faith Winocur, 11, of Potomac.