At 38, Boise cyclist Kristin Armstrong is aiming to make her third U.S. Olympic team this summer, joining a growing number of athletes pushing the age boundaries for Team USA.

Armstrong will ride in the inaugural Exergy Tour, a $100,000, five-day women’s professional cycling stage race through southwestern Idaho. The race begins with a Boise prologue beginning and ending at Julia Davis Park on Thursday evening.

And although Armstrong plans on this being her final season as a professional cyclist, she isn’t quite ready to close the door entirely.

“I would have thought my last Olympics would be my last one. No way I’m going until I’m 38,” said Armstrong, who won the time trial at the 2008 Beijing Olympics. “I am for sure not going to continue on for another four years, but I think about these other women in their 40s now.”

Women like U.S. swimmer Dara Torres, who won a silver medal in the 2008 Games at 41. It was her fifth Olympic appearance dating back to 1984.

Armstrong retired after the 2009 season and gave birth to son, Lucas. But the sport drew her back and now she is among the top contenders for a spot in July’s London Olympics.

She threatened to “pull another Brett Favre” and keep riding at Wednesday’s Exergy Tour kickoff, a joke about the oft-retired NFL quarterback. Armstrong said she is riding as well as she did in 2009, an assertion backed up by the power meter on her bike and a string of stellar results.

“As long as you’re still at a high level of competition and still love doing what you’re doing, why stop? ” said Armstrong, who didn’t pick up professional cycling until she was in her late 20s.

“It’s intriguing to me to see how long these athletes can keep going. It’s going to change sports in general.”

Sports like gymnastics, where 2008 all-around gold medalist Nastia Liukin is attempting to make another Olympic team at 22.

“In ’08, I was 18, and people said I was over the hill,” Liukin said earlier this month at a U.S. Olympic media event in Dallas. “Your career doesn’t have to be over at 16.”

No it doesn’t. At least not for many Olympians.

Triathlete Hunter Kemper is 36 and headed to his fourth Olympics. Taekwondo athlete Steven Lopez is 33 and going to his fourth Olympics.

Distance runner Bernard Lagat is 37 and chasing a fourth appearance.

The average age of the U.S. Olympic swim team has risen from 18 in 1972 to nearly 23 in 2008, according to USA Today. Michael Phelps, who turns 27 in June, will swim in his third Games in London. Swimmers like Natalie Coughlin (29), Brendan Hansen (30), Amanda Beard (30) and Janet Evans (40) are trying to make the U.S. team.

“People are telling us that gymnasts can only be this age and swimmers retire at this age. Who are these people telling us it’s time to stop?” Armstrong said.

Armstrong said she is better positioned to handle the Olympics than she was in 2004, when she made her first team. Armstrong finished eighth in the road race in Athens. She often says she was merely “a participant” in those Games. Four years later, Armstrong achieved her dream of winning gold.

Now she wants to go back. And once she gets there, Armstrong said, she’ll be tough to beat with a combination of skill and smarts.

“Third- and fourth-time Olympians, those are the ones that are going to be hardest to knock down,” Armstrong said. “ The experience of stress, the experience of eating on the road, of being in the spotlight, experience with media trying to get at them non-stop. It’s a lot of balance. It takes experience.”

Brian Murphy: 377-6444