07/03/2012 06:29 pm ET

Dara Torres And Other Olympians Over 30

Dara Torres, 45, is the oldest swimmer to compete at trials this year -- while she didn't make the team, her displays of athleticism at such an elite level continue to impress spectators. That doesn't mean it's easy for her.

“I look at the younger kids and I wish I were like them, and look at the way they bounce back, and come back to another workout later, when all I want to do is take a nap because I’m so tired,” Torres told TIME's Alice Park recently. “But you have to overcome that, and be like, ‘OK, I’ll feel better the next day.’ That’s the mentality you have to have in order to get through it.”

Torres must contend with a changing endocrine system -- though she is not yet in menopause, hormonal changes associated with perimenopause can begin as early as mid-30s. What's more, "physiological aging" -- that is, the ability to maintain muscle mass and recover from workouts -- begins at age 30, according to an article in Reuters that considered the capabilities of older athletes during the 2008 Olympic Games:

Dr. Michael Joyner, an anesthesiologist at the U.S. Mayo Clinic who studies the effects of ageing on athletes, said normal "physiological" ageing starts at 30 but athletes can delay this until their late 30s or 40s with prolonged, intense training.

He said lab data showed that for physiological factors associated with endurance sports the decline is about 10 percent per decade starting at 30 but this can be halved with continued hard training, especially if it remained intense.

Indeed, the regularity with which over-30 athletes appear during the Olympics attests to the reality that determination, targeted training and yes, as Reuters points out, financial opportunities that afford athletes prolonged focus on their Olympic careers, have contributed to an athletic corps that aren't exactly spring chickens. Here's a list of Olympians who have allegedly crossed the threshold into physiological aging -- and aren't letting it hold them back one bit:

12 Olympians From 30 To 45