By Pritha Sarkar

RIO DE JANEIRO (Reuters) - If there was a gold medal on offer at every competition for the oldest gymnast on show, Oksana Chusovitina would have needed to hire Fort Knox to stockpile a hoard of precious metal.

In a sport overpopulated by tiny teenagers, 41-year-old Chusovitina has kept her body "lean and mean" for over four decades so that she can compete against rivals younger than her 17-year-old son Alisher.

"When I compete ... if they gave a few more marks for age it would have been great!” quipped Chusovitina, whose gamble to keep competing paid off as she put younger challengers to shame on Sunday by qualifying for the eight-woman vault final.

So long is her career that the majority of her Rio rivals were not even born when she was a member of the triumphant Unified Team, representing former Soviet republics, in 1992.

There was certainly a lot of love in the Rio Olympic Arena for the oldest ever gymnast to compete at a Games.

The cheers were loud and prolonged when the venue's MC introduced the Uzbek as "a living legend" and the volume went up a few notches as she sprinted down the runway before launching into her first vault -- a layout front somersault with 1-1/2 twists.

A hop back on landing did little to dampen the mood and a score of 15.166 proved that she was not in Rio to simply celebrate competing at a record seventh Olympics for a gymnast.

Wearing a pink and white shimmering leotard, her toned arm muscles were in full display as she lifted off for her second vault -- a double twisting Tsukahara -- which earned her 14.833.

“I really love the sport, I love to give pleasure to the public. I love to come out and perform for the public and for the fans,” said Chusovitina, who has competed under the Soviet Union, Unified Team, German and Uzbek flags during her career.

Asked how she rated her performance, she assessed: “I’m alive I'm well and that means everything’s okay.”

The Uzbek's gymnastics lifespan defies logic as the next oldest competitor in Rio after her is 32-year-old Vasiliki Millousi from Greece.

While Chusovitina does not think what she is doing is that remarkable, 1996 Olympic champion Kerri Strug said it was "unbelievable" that one of her contemporaries was still going strong.

"Kudos to her for being so disciplined with her diet, staying lean and mean at that age. It only gets harder to compete with these youngsters but she’s doing it," the American told Reuters.

"She’s had a child, and to keep getting into a leotard and stay in such phenomenal shape. To be able to bear all that pounding over the years, I don’t know how she does it.

"In gymnastics, it usually one or two Olympics but seven? It’s just crazy."

(Reporting by Pritha Sarkar; Additional reporting by Alexandra Ulmer; Editing by Brian Homewood and Frank Pingue)