NEW YORK (Reuters) - When Diana Nyad became the first person to swim the 110 miles from Cuba to Florida without a shark cage, baby boomer-aged fitness experts greeted the 64-year-old's achievement with pride and delight but not disbelief.
The aging body, they said, is capable of more than previously thought.
"Today's 60-to-65 is not what it was one or two generations ago," said Dr. Angela Smith, an orthopedic surgeon and past president of the American College of Sports Medicine.
"I thought my very active grandmother was fabulous because at 60 she could still touch her toes. Now fabulous is swimming from Cuba to Florida. That's a huge difference."
Smith is a competitive skater on the verge of 60, which places her, like Nyad, firmly among the estimated 78 million baby boomers who, defined as the group born between 1946 and 1964, make up about 26 percent of the U.S. population, according to U.S. Census reports.
"Bruises take a lot longer to heal, and it's harder to build and maintain muscle but, guess what, you get it back," Smith said about boomers. "We know that you can maintain a lot more muscle mass than we thought."
She said mental toughness, surely a factor in Nyad's success, comes with experience.
"We know that older people make mental connections in ways different from 20-something athletes," Smith said. "They use strategy, technique better."
When she competes in national skating championships, her goal is no longer to win but to try to gain something technically or to develop a new skill.
"It's not the way a child would do it," she explained.
Utah-based fitness professional Kathy Smith has known Nyad since the early days of the Women's Sports Foundation, a non-profit tennis great Billie Jean King founded in 1974 to empower girls and women through sports and activity.
Kathy Smith, author of "Moving Through Menopause," said what her friend accomplished is the cumulative effect of living a certain lifestyle.
"You don't just get up and say ‘I'm going to do it.' It's like a bank account you keep investing in with lifestyle choices, mental habits," she said. "With that comes the reward of doing something later in life."
Smith, 61, said after 35 years in fitness, her message hasn't changed but her workout has.
"I started as a cardio animal, a marathon runner," she said. "As I've gotten older, my strength training has increased because as you lose muscle mass, you notice you need more strength training."
She said she can do many things she used to do if she builds in longer recovery time.
"I think this is the generation that's been there, done it," Smith said. "I remember my parents, my community saying that if you train you won't be able to get pregnant. We fought for the right to move."
Dr. Wojtek Chodzko-Zajko, an expert on ageing and physical activity and professor of Kinesiology and Community Health at the University of Illinois at Urbana-Champaign, thinks Nyad's swim says more about the human spirit than it does about ageing.
"I think it's astonishing, but I don't think it's miraculous or voodoo," he said "We could just as easily be having this conversation about someone in the Boston Marathon."
Relatively speaking, he said, world record performances decline less with age in endurance activities, such as Nyad's swim, than in short-burst power or sprint activities.
"The idea that there is no loss at all is unrealistic," he said. "Diana Nyad in her 60s is not the same as in her 40s, but a lifetime commitment pays off. The change is less."
Editing by Patricia Reaney and Nick Zieminski