By Erik Kirschbaum

COLOGNE, Germany (Reuters) - It is hard not to feel a lump in your throat when listening to Oxana Chusovitina tell the heart-breaking story of how she ended up in Germany.

The 32-year-old gymnast is heading to her fifth Olympics in August as the reigning European vault champion and will compete for Germany, the third country she has represented.

She first marched under the banner of the former Soviet Union's Commonwealth of Independent States (CIS) at the Barcelona Olympics in 1992 and then competed for Uzbekistan in Atlanta in 1996, Sydney in 2000 and Athens four years ago.

Chusovitina moved to Germany for one reason -- to save the life of her son Alisher.

He was diagnosed with acute lymphocytic leukemia at the age of three in 2002. There were no specialist oncology facilities in Uzbekistan and Chusovitina's family had no health insurance.

So Chusovitina, who won an Olympic team gold in 1992 and eight world championships on the vault, went west for treatment and was welcomed in 2002 in Germany, where donations were raised to help fight her son's cancer.

She also put her nominal prize money towards covering costs.

"My son is my whole life," Chusovitina said in an interview with Reuters after a high-energy 90-minute training session in her adopted home of Cologne.

"I know every mother says that. But our bond is special. When he was ill I was devastated. He's my motivation."

AGE BARRIER

Chusovitina has defied conventional wisdom that gymnastics is a sport for teenagers. The only woman gymnast to appear at four Olympics, she has leaped over the age barrier and acknowledges her son's battle with cancer played a role in that.

"I'm fortunate to be able to continue in a sport I love so much," said Chusovitina. "And I can't tell you how grateful I am to everyone who helped."

She sometimes took part in all four women's apparatus disciplines at tournaments, rather than focus on one or two, to increase her chances of winning prize money.

"The whole world helped," she said.

A warm smile spreads across the face of the gymnast, who weighs 44 kg and stands just 1.53 meters tall, when she talks about her son's improved health.

He is doing well, leading the life of an eight-year-old German boy, and he now needs only quarterly blood analyses.

"My heart doesn't ache any more the way it did because I can see he is healthy," said Chusovitina, who obtained German citizenship in 2006. "He does everything other children do and sometimes he comes to gymnastics training with other children."

Her husband, former Uzbekistani Olympic wrestler Bakhodir Kurpanov, is now a wrestling coach and shuttles between Cologne and Uzbekistan.

Chusovitina won a team gold medal with the CIS as a 17-year-old in 1992, after winning her first world championship for the Soviet Union in 1991.

She holds the record for the most individual world titles in a single event after winning the vault eight times.

The 2000 Olympics came nine months after she gave birth to Alisher and she said she was not able to get back to peak shape in time. In 2004, she was recovering from injury.

LONDON GOAL

In April she won the vault gold at the European championships in France and became the oldest woman to win a major gymnastics title. It was a victory that gave Germany their first European women's gold medal in 23 years.

Chusovitina said Germany was her home now and she got goose bumps when she heard the national anthem of her adopted country.

"I felt at home in Germany right away," she said in fluent German. "I want to give something back to the country that's done so much for me."

"And I like the national colors. I think they look good on me."

Chusovitina is loathe to make any predictions about Beijing but, with her 33rd birthday on June 19, she has no plans to retire.

"Before, everyone said: 'It's hard to keep going after the age of 20'. But more and more gymnasts are staying in the sport beyond 20.

"I think it's a good thing. I had a difficult spell at the age of 18 or 19. But after I got through that phase I enjoyed every minute.

"I've been doing gymnastics for 25 years but still love it. I love coming to training and the competition. I'll keep going as long as I can. My goal is to keep going until London in 2012."

(Editing by Robert Woodward)