AFP

Shamed cyclist Lance Armstrong wants to return to competitive sport, but says the driving force behind his belated doping confession was the well-being of his five children.

"The biggest hope and intention was the well-being of my children," Armstrong told talk show host Oprah Winfrey in the second segment of their televised interview that aired in the US on Friday.

In the first instalment aired on Thursday, the 41-year-old Texan admitted for the first time that an array of performance-enhancing drugs helped sweep him to a record seven Tour de France titles from 1999-2005.

Years of aggressive denials - including vitriolic attacks on those who questioned him, collapsed last year when he was stripped of his Tour titles and banned for life by the US Anti-Doping Agency.

"The older kids need to not be living with this issue in their lives," Armstrong said. "That isn't fair for me to have done to them. And I did it."

But Armstrong said that if confession could help him regain a place in sport - in triathlons or marathons - he'd jump at it.

"Hell yes, I'm a competitor," Armstrong said, adding that he didn't think he deserved the "death penalty" of a lifetime ban.

"Frankly, this may not be the most popular answer, but I think I deserve it," he said, telling Winfrey that former team-mates who implicated themselves in testifying against him received lesser punishments.

"I deserve to be punished," Armstrong said. "I'm not sure that I deserve a death penalty."

When Winfrey noted that virtually every article on the once revered cyclist now begins with the word "disgraced" Armstrong said he felt it fit.

"But I also feel humbled. I feel ashamed. This is ugly stuff," he said. "I'm deeply sorry for what I did. I can say that thousands of times and it may never be enough to get back."

The first instalment of the interview was a ratings winner for Winfrey, with its estimated 3.2 million viewers in the United States making it the second-most-watched show ever on her fledgling OWN network.

However, it left many still skeptical of Armstrong's motives and methods, doubtful that he felt real remorse.

Genuine emotion seeped through on Friday. Armstrong's eyes reddened and his voice cracked as he described telling his 13-year-old son Luke: "Don't defend me anymore" when his transgressions at last caught up with him.

"When this all really started, I saw my son defending me and saying, 'That's not true. What you're saying about my dad is not true.'

"That's when I knew I had to tell him," Armstrong said. "And he'd never asked me. He'd never said, 'Dad, is this true?' He trusted me."

Armstrong recalled the days in October, after USADA released the report documenting its case against him, that led to his stepping down as chairman of the Livestrong cancer charity he founded and then leaving the board entirely.

"I wouldn't at all say forced out," Armstrong said. "I was aware of the pressure.

"It was the best thing for the organisation but it hurt like hell... That was the lowest."

He discussed the financial fallout, in particular the stampede of sponsors away from him with sportswear giant Nike in the lead.

"You could look at the day or those two days or the day and a half where people left," he said. "That was a $75 million day."

Armstrong's admissions could carry legal repercussions.

The US Department of Justice is close to making a decision on whether to add the government's name to a complaint lodged in 2010 against Armstrong by former fellow US Postal Service teammate Floyd Landis.

The Postal Service, a federal agency, paid $30 million in public money to sponsor Armstrong's team - and may now seek to get it back.

Armstrong again denied that he used drugs in his comeback from retirement in 2009 and 2010, saying he'd promised his ex-wife Kristin that he would "never cross that line again."

He also denied USADA chief Travis Tygart's assertion in a "60 Minutes Sports" interview last week that someone in Armstrong's camp offered the agency a $250,000 donation in what could be seen as an attempt at a pay-off.

"That's not true," Armstrong said, noting that it wasn't in USADA's official case against him.