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:

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  • Yelena Isinbayeva, 30

    Track & Field, Russia Isinbayeva won gold in pole vault events in the 2004 Athens Olympic Games and the 2008 Beijing Olympic Games. This year's games will be her third time as an Olympian.

  • Ky Hurst, 31

    Swimming, Australia This will be Hurst's second Olympic games -- in 2008 in Beijing, he finished 11 in the men's 10 km open water event.

  • Phil Dalhausser, 32

    Volleyball, USA In 2008, Dalhausser and his partner Todd Rogers (age 38!) brought home the gold medal in Men's Beach Volleyball. This will be their second Olympic games.

  • Phillips Idowu, 33

    Track & Field, Great Britain Idowu has competed in three other olympics: Sydney's 2000 Games, Athens in 2004 and Beijing in 2008, where he won a silver medal in the triple jump.

  • Luciana Aymar, 34

    Field Hockey, Argentina Aymar <a href="http://www.buenosairesherald.com/article/103471/luciana-aymar-argentinas-flag-bearer-at-london-2012" target="_hplink">is considered</a> to be the best field hockey player in the world and has won medals at the Sydney, Athens and Beijing games.

  • Chris Hoy, 35

    Cycling, Great Britain Hoy has medaled in every game he has participated in, beginning with a silver medal in the team sprint at the Sydney Olympic Games in 2000. He won several gold medals in Athens and Beijing. This will be his fourth Olympics.

  • Amy Acuff, 36

    Track & Field, USA Acuff has been at every Olympic games since 1996 and will compete for Team USA for the fifth time next month.

  • Hunter Kemper, 36

    Triathlon, U.S.A. Kemper has been to each Olympic games since 2000 and, <a href="http://www.nbcolympics.com/athletes/athlete=hunter-kemper/index.html" target="_hplink">according to this profile</a>, is getting better with age: his ranking has steadily improved after each game: he finished seventeenth in Sydney, ninth in Athens and seventh in Beijing.

  • Paula Radcliffe, 38

    Track & Field, Great Britain Radcliffe currently holds the world record for the fastest marathon time for any woman, having completed the 2002 Chicago marathon in 2:15:25. She will compete in the London Olympics for the fifth time, having first competed and earned a bronze medal during the 1996 games.

  • Ryan Giggs, 38

    Soccer, Great Britain Though he has been a famous member of Manchester United since 1990 when he was 17, this will be Giggs's first Olympic games. He is one of only three players over the age of 23, per the regulations for Team Great Britain.

  • Michael Diamond, 40

    Shooting, Australia A two-time gold medalist in trap shooting, Diamond has competed in five previous Olympic games.

  • Heather Blitz, 43

    Equestrian, USA Blitz and her horse, Paragon (age 9), are alternates on Team USA for the 2012 games.