(USA TODAY) -- Swimmer Dara Torres, 45, is still sprinting in the pool; she is a favorite to qualify for her sixth Olympics when trials begin next week.

Pitcher Jamie Moyer, 49, is still striking out batters; he became the oldest pitcher to win a game in the majors in April and followed with another win for the Colorado Rockies in May. Now, the Baltimore Orioles have their eye on him.

Not bad, right? Now add more than 20 years.

Japanese mountaineer Tamae Watanabe, 73, is still climbing; she set a world record last month, becoming the oldest woman to scale Mount Everest, the tallest mountain in the world. She broke her own record, set when she was 63.

Expect more like these, fitness experts say -- exceptionally healthy adults who are transforming our image of aging.

"My guess is that as more people 'age up' who have been active their whole lives and are really committed, we will see more interesting things from people in the 60-to-80 age range," says Michael Joyner, a Mayo Clinic anesthesiologist and a specialist in exercise science in Rochester, Minn.

And maybe, he adds, they will inspire a nation where many sit all day in front of a computer.

Few of us will ever come close to these exceptional levels of fitness at any age, but what stops so many people from staying fit as they grow older? Exercise physiologist Barbara Bushman says 24% of adults over 65 are totally inactive, and fewer than 40% meet the baseline recommendations for exercise (150 minutes a week of moderate-intensity physical activity, such as brisk walking, or 75 minutes of vigorous activity, such as jogging or swimming.)

"The short answer is that most of society is not pushing themselves hard enough," Joyner says. "However, at the same time, there is this emerging subgroup of fit or super-fit middle-aged and older people who are redefining things."

When Janet Evans, 40, started her comeback last year after 15 years off Olympic-level swimming, Joyner said, "This is the whole new normal emerging."

How much does it help?

He notes that motivation and resilience "are the key."

But in a society where obesity is an epidemic, what kind of extra motivation do we need?

"Regular physical activity can favorably influence a broad range of body systems and may be a lifestyle factor that discriminates between those who experience successful aging and those who do not," says Bushman, a professor of kinesiology at Missouri State University and co-author of the American College of Sports Medicine's Complete Guide to Fitness and Health.

Some scientists go so far as to say exercise actually slows aging. A 1990 study comparing masters athletes and sedentary people found that those who continue to engage in regular vigorous exercise show just half the rate of decline in maximal aerobic capacity as sedentary people. Recent research shows aerobic activity is important for healthy cognitive function. And regular exercise eases the stiffness and pain of arthritis.

Sports doctor and triathlete Jordan Metzl knows this firsthand. He says he has some arthritis, but exercise helps him. In his new book, The Athlete's Book of Home Remedies, he has a section on strengthening exercises you can do at home to help protect ligaments and joints.

They aren't 20 anymore

Most of us begin to notice physical decline in our mid-30s, but it doesn't have to be all or nothing, Bushman says.

Evans, who follows the latest research on training methods, says she has had to take better care of herself, including getting more sleep, shedding a few pounds and taking more time to recover between workouts than when she was younger.

Though Evans hasn't suffered any career-threatening injuries, Torres and Moyer haven't been as lucky. Moyer missed the 2011 season after having ligament replacement surgery, and Torres has had multiple surgeries, including an innovative procedure after the 2008 Olympics on her left knee to regenerate cartilage. Before that, she couldn't walk without a limp, and the muscles in her leg were atrophying.

"There have been isolated examples of exceptional feats by people in their 40s and 50s for many years," Joyner says. "These are happening more often and are more widely noticed."

When Bushman heard about Watanabe, she laughed and said, "Now that is successful aging."

"Although not everyone has interest or ability to achieve a feat like climbing Everest, people of all ages can take steps today to develop a complete exercise program," Bushman adds.

She recommends a focus on aerobic exercise for cardiovascular fitness, resistance training for muscular fitness, flexibility exercises, and neuromotor training for balance, agility and coordination. "No one is too old, or too young, to invest in their future health."

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