The 59-year-old Watson lost his bid to become the oldest British Open champion in a playoff on Sunday in Scotland. Meanwhile, the 37-year-old Armstrong clung to second place in his bid to win an eighth Tour de France.

"Age is certainly not a barrier" to competing at the highest levels, said Dr. Marc Philippon, an orthropedic surgeon whose pro athlete patients include Watson. "The added dimension of making history" probably helps them perform when the competition gets fierce, he said.

Philippon did hip surgery in 2000 on golfer Greg Norman. The Shark tied for third and at one point led last summer's British Open - at age 53. He missed the cut this weekend at Turnberry, Scotland, while Watson was chasing history.

Few aging athletes wind up like swimmer Dara Torres, who won three Olympic silvers as a 41-year-old swimmer last summer. Golf is one sport where they stand a good chance of staying competitive.

"Golf does not require the same aerobic capacity or fitness - it's a skill game," and skill can be maintained, said Dr. Andrew Gregory, a Vanderbilt University sports medicine specialist.

"To be a great old athlete you probably have to have been a great young athlete," said Carl Foster, past president of the American College of Sports Medicine and a professor at the University of Wisconsin in LaCrosse.

"Tom Watson was a good golfer when I was a young man, and that's a long time ago," he said.

Torres, Watson and Armstrong "all were at one point extraordinarily good, so they have skills" they can maintain, Foster said.

Staying fit and maintaining endurance is a challenge, though.

"You lose distance, because of loss of muscle. You lose flexibility in your shoulders and your spine. You can't rotate, you can't generate the same clubhead speed to hit the ball very hard," Gregory said.

To stay in the game, an older athlete must be fit beyond what is needed for his specific sport, said Ralph Reiff, an athletic trainer and director of a sports performance program at St. Vincent Hospital in Indianapolis. That means cross-training with weights, and biking or swimming to maintain cardiovascular fitness.

"What we focus on is flexibility and range of motion, because those are the things that leave us as we get older, and also endurance. That's the one area that might have caught up with Tom a little bit," Reiff said of Watson, who fell apart in the playoff round on Sunday.

"Maybe a little fatigue sets in that wouldn't have set in for a younger person," Foster agreed. "It's still a repetitive sport, and stuff adds up after awhile."

The success of geezer athletes, as Watson referred to himself, is inspirational, Gregory said.

"It gives all of us who are past our prime reason to be active," he said.

Reiff said it challenges notions of an age limit to successful competition.