Olympic gold medallist Mary Lou Retton is "still fighting" a rare form of pneumonia that has left her in an intensive care unit for more than a week, her daughter said on Wednesday.

Retton, a former U.S. gymnast, captured the heart of the nation with an historic gold medal-winning performance at the 1984 Olympic Games in Los Angeles.

"Thank you so much for all the love and support you have given to my mom," her daughter Shayla Schrepfer said in a video on Instagram.

"My sisters and I are overwhelmed. We didn't even realize that there are so many people out there that love her just as much as we do."

On Tuesday another one of her four daughters, McKenna Kelley, said her 55-year-old mother was unable to breathe on her own and did not have health insurance.

A fundraising page set up by the family to help cover Retton's medical bills had far exceeded its $50,000 goal on Wednesday, with $277,206 pouring in from nearly 5,000 donors.

"She's still fighting," Schrepfer said.

"It's going to be a day by day process... She is being treated by the best of the best professionals here and it has been such a blessing to have their hands on her.

"So please continue the prayers and we can not thank you enough for the love and support you guys have shown."

The Fairmont, West Virginia native became the first American woman to win the all-around gold medal at the Olympics, doing so in dramatic fashion by scoring a perfect 10 on the vault to edge Romania's Ecaterina Szabo.

Retton also won two silvers and two bronzes to walk away as the most decorated athlete at the 1984 Games - all while still a high school student.

The performance earned her adoring fans and the moniker "America's Sweetheart".

She was inducted into the International Gymnastics Hall of Fame in 1997.

(Reporting by Rory Carroll in Los Angeles; Editing by Toby Davis)