DES MOINES, Iowa — Olympic gold medalist Shawn Johnson said she is unlikely to compete at the 2009 world and national gymnastics championships.

Johnson won the 2007 individual all-around world championship and followed with four Olympic medals this year in Beijing - including gold on the balance beam.

The national championships next August in Dallas and world championships next October in London appear doubtful, she said.

"To compete next year, I'd have to start training directly after the tour," Johnson, 16, of West Des Moines said Friday by phone before a performance of the national Tour of Gymnastics Superstars in East Lansing, Mich.

"It would be hard to get into the kind of shape I'm happy with. If I did come back, I'd want to be better than ever, even if it takes three years. I'd want to be more perfect and precise."

Johnson said she's unsure when or whether she will return to competition.

"I'll definitely take a little break," she said. "The 2012 Olympics are the huge question. When you've had a passion and had goals and you've realized them, it's hard to make new goals. I'll have to decide whether I want to push for another four years."

She said she might return to West Des Moines' Valley High School in January after skipping this semester - or she might not.

"I'm not sure yet," Johnson said. "I'm taking it one day at a time. This is one of the most important times for me in terms of opportunities. But I will start back to school in January whether it's with tutors or at Valley."

Johnson has had a whirlwind of appearances since her Olympic triumph, appearing on television shows hosted by Jay Leno, David Letterman, Oprah Winfrey and Ellen DeGeneres in addition to the tour, television commercials and sponsor obligations.