Diana Nyad swim ends early, but senior athletics going strong

(CBS) It's over. Battling winds and ocean currents, Diana Nyad ended her second bid to swim from Cuba to the Florida keys. The 61-year-old athlete was safely pulled from the water after swimming for 29 hours - roughly halfway through the marathon swim, which had been expected to last 60 hours, the Associated Press reported.

PICTURES - Amazing aging athletes: Buff bodies battle at National Senior Games

Before the swim on Monday morning, Nyad explained why she was attempting such an outlandish feat. "I'm almost 62 years old and I'm standing here at the prime of my life," she told CNN. "I think this is the prime. When one reaches this age, you still have a body that's strong but now you have a better mind."

Was Nyad preaching to the choir? There are plenty of athletes who continue to perform and even compete at a high level despite their advancing age. Dr. Angela Smith, past-president of the American College of Sports Medicine, pointed to swimmer Dara Torres and tennis ace Martina Navratilova, both of whom continued to compete at an elite level in their forties, as well as to Nyad.

"Martina Navratilova showed that better strategic thinking made up for the loss of speed and power," said Dr. Smith - herself a competitive figure skater at the age of 57.

She said researchers used to think there was an age limit beyond which people were incapable of building muscle strength, but that recent studies had failed to find it, adding, "Now we don't know what the limits are."

No limits? Not convinced? Just take a look at some of the amazing athletes who competed in Texas last June in the 2011 National Senior Games.