CHICAGO — Dara Torres jokes that she had trouble reading the scoreboard after winning the first of two events at the Olympic swimming trials.

Her eyes just might be the only part of her body showing some age.

At 41, Torres is heading for her fifth Olympics — despite taking several years off, giving birth just two years ago and undergoing two surgeries within the past eight months.

Her remarkable feat has left armchair athletes doing a double-take. But exercise experts say Torres' success at least partly reflects advances in training — and that many of us could come closer to similar achievements than we think.

True, genetic makeup certainly has helped Torres compete at an elite level so relatively late in life. As Dr. Kathy Weber, director of women's sports medicine at Chicago's Rush University Medical Center, puts it, she has the right "protoplasm."

She also has three other key advantages — opportunity, motivation and incentive to train hard, said exercise physiologist Joel Stager, who directs a science of swimming program at Indiana University.

And those things aren't impossible to achieve, as Torres has demonstrated.

"It shows us what we can do," Stager said. "It's just that most of us don't."

Torres qualified for the Olympics by beating swimmers nearly half her age in the 100-meter freestyle Friday, then set an American record Sunday in the 50-meter freestyle trials.

Most of the other swimmers on the U.S. women's team were born after Torres first competed in the Olympics, at the Los Angeles Games of 1984. The youngest, Elizabeth Beisel, was born shortly after the Barcelona Games of 1992, Torres' third Olympics.

Torres' regimen includes lots of resistance training — repetitive exercises using external force to push against muscles to make them stronger and increase their endurance.

This includes weight machines, free weights, and the type of simple floor exercises Torres does several times weekly: Lying on her back, she lifts and stretches each leg while also pushing against it with her arm.

These exercises also work to strengthen "core" muscles in the abdomen and back, which gives arms and legs "a better platform to work from," said Carl Foster, former president of the American College of Sports Medicine.

Core exercises are a relatively recent trend in sports medicine, reflecting a better understanding of how to improve training to prevent injury, said Foster, a professor at the University of Wisconsin in LaCrosse.

For athletes at any level, a gradual decline in endurance and speed occurs in the 30s and 40s, roughly half a percent a year, Stager said. And even that's with continued training.

While it would be virtually impossible for novice athletes to start rigorous training in their 30s and expect to reach Olympic level by their 40s, healthy people can significantly improve their athletic performance with the kinds of exercises Torres does, doctors say.

The key is to avoid overtraining, and to take time to warm up and cool down, Weber said.

Torres' training has helped her fight the typical slow decline in muscle mass that usually begins in the 30s, and given her sculpted arms and rock-hard abs that would make any 20-year-old jealous.

Dr. Andrew Gregory, a Vanderbilt University sports medicine specialist, noted her appearance has prompted doping speculation in some circles. Tests against some drugs aren't foolproof, so Torres' record of negative tests and strong denials won't be enough for some people. Nor will her offer to take a lie detector test.

But she has been a great swimmer for so long that doping seems more unlikely than for many athletes, said Dr. Walter Lowe, sports medicine director at the Baylor College of Medicine.

Torres has retired twice from competitive swimming, gave birth in 2006, and was briefly sidelined by shoulder and knee operations, early this year and in late 2007.

While other people might view these as good excuses for slowing down, doctors say it's not surprising Torres was able to bounce back quickly, given her years of training.

Stager said he has worked with Masters swimming, a national competitive program for amateur adult swimmers of all ages. Participants typically swim nearly every day of the week, and often look decades younger than their years, he said.

Torres "is a benchmark" for that kind of dedication, and she shows that devotion to exercise can help redefine aging, Stager said.