NEW YORK - Seven-times Tour de France champion Lance Armstrong will swap his bicycle for running shoes in Sunday's New York Marathon, his first attempt at the 26.2-mile distance.

"Always in the back of my mind I had thought about doing a marathon," Armstrong told a news conference on Friday. "I did my first run two or three days after I retired following the 2005 Tour.

Seven-time Tour De France winner Lance Armstrong smiles as he is introduced to talk about his upcoming running of the New York City Marathon at a news conference in New York November 3, 2006. [Reuters]

"I understood I would lose my condition and put on 10 or 15 pounds but I didn't want it to get to 50. This was a logical step."

He said he entered as a personal challenge and to raise money for his foundation and for cancer research.

The 35-year-old American, who overcame cancer to win his seven Tour titles, said this was not the start of a new career.

"My days as a professional in high-level sport are done," said Armstrong.

One hundred runners have signed up to race as part of Armstrong's team, raising more than $600,000.

Former winner Alberto Salazar will pace the American for the first 10 miles before ex-Olympic champion Joan Benoit Samuelson leads him for the next 10.

CENTRAL PARK

Olympic 1,500 and 5,000 metres winner Hicham El Guerrouj will run with him for six miles before leaving Armstrong to finish in Central Park.

"It's not about being competitive, it's a personal goal," said the former cycling champion.

"If I could break three hours I could leave happy."

Armstrong said running was more convenient than cycling.

"My schedule is so busy these days but I can bring a pair of running shoes with me everywhere I go and run for an hour and be complete," he said, adding his longest run was for 16 miles two weeks ago.

Race director Mary Wittenberg welcomed Armstrong, saying he was an inspiration.

"He says to all of us in his actions, get up and fight," Wittenberg said.

Nine-times winner Grete Waitz will present Armstrong with his medal after the race, the same one given to all finishers in the 37,000-strong field.

The Norwegian said Armstrong became a role model for her after she was diagnosed last year with cancer.

Waitz said his story inspired her to exercise and stay positive no matter how poorly she felt during treatment.

"I got an e-mail from Lance," Waitz said. "He heard about me having cancer and he wrote, 'Like me you are a fighter and I know you are going to beat this'."