There was nothing unusual about the start of the Bonne Bell 10-kilometer race this spring. More than 3,200 women crowded the line, responded to the gun and strung out along the course.

But what happened at the four-mile mark was anything but ordinary. Taking the lead, seventh grader Ann Hoefler held on and defeated Kathy Hibbert to become the youngest winner in the race's history.

Now, Hoefler, 13, sits on a couch in her Silver Spring home, her hair in barrettes and her teeth in braces, shy as can be. Her running companion, Judy Carr, a ninth grader at White Oak Junior High School whom Hoefler met two years ago, turns to her friend and they giggle.

Hoefler looks over to her mother Pat, who runs a nursing board review business while coaching cross country and track at the St. John the Baptist CYO. It is through her mother that Hoefler receives her training; it was through her mother that she has blossomed as a distance runner.

Pat Hoefler is also a runner. In 1980, she completed three marathons, with a best of 3 hours 50 minutes. It was during her mother's marathon training that Ann Hoefler began to run seriously.

Said Pat Hoefler, "I was getting ready for a marathon. I took her on a 10-mile run. She looked better than I did. Then she started training with me on distance runs. Her cross country times went down. She was running 30-35 miles per week and handling the distance well. She was enjoying it and improving."

At that time, Ann Hoefler began competing in the sprints on the CYO track team. "Then I wanted to run with Mom. I wanted to be good at it. So I began putting in the time.

"When I started to get better, I decided to stick with it. I thought, why should I stop. And I began to like it more."

She ran her first distance race in 1981, a 10-kilometer run in which she finished in 41 minutes. In that year, she broke the national 11-year-old age-group record with a 1:20:39 for 20-kilometers in the Avon 20K.

In November of 1982, she set another age-group record, this time by winning the WETA 10-kilometer run in 36:23. Her personal bests include a 57:08 15-kilometer in the 1983 Avon 15K, a 59:50 10-mile in the Cherry Blossom last March and, most impressively, a 4:58 mile in a Montgomery County junior high track meet last month. That was the fastest mile by a girl her age in Maryland history.

"When I began to run, I never thought I would get good at it. Never even thought of it. I looked up to Anne Densmore." Densmore, 13, led the Bonne Bell for the first three miles before yielding to Hoefler.

Hundreds of articles have been written about the negative effects of long-distance running on young runners, but Hoefler is in good hands. Her mother and close friend Dick Carter, who met them four years ago when they joined the CYO team, carefully monitor all workouts and races.

"It's good that they (young runners) run up to a point," says Carter, a 2:51 marathoner who runs 20 to 30 miles a week. "Activity is good for people. However, Annie's running is on the borderline."

"Dick holds us back," Pat Hoefler says. "It is easy to get carried away." She then explains that although her daughter has qualified for national competition, Carter will not permit her to run.

"If she starts to conquer the world," he says, "what is left? Running in the nationals is a big step toward getting carried away."

As for the future, Ann Hoefler has begun to think about the Olympics, and would like to attend college. She is interested in computers and math, and is an honor roll student at White Oak. Some day she would like to complete a marathon.

"I don't want to try a marathon right now," she says. "My favorite distance is 10K because it's not too long, and it's not too short. It's just perfect. Probably the farthest I'll ever run is the marathon. But I'm not going to worry about it."