Florida:
Bernice Bates is 91 years old, and she's more flexible than people a third of her age.
Guinness World Records recently awarded her the title of "Oldest Yoga Teacher."
While there might be other, older yogis, Bates completed the lengthy documentation process required by Guinness. Her daughter nominated her earlier this year.
Bates first began practicing yoga 50 years ago, after she saw it on a television program.
These days, the great-grandmother teaches once a week at the community center of her Florida retirement village.
Her students are usually a decade or two younger than she is.
Bates believes in gentle yoga: no sweaty, strenuous or competitive stretching in her classes.
"You may not do it perfect, but there's no perfect person," she said.
Kathleen Techler, 86, has been taking Bates' class for five years. She can easily go into a plow pose - lying flat on her back, raising her legs all the way over her head and rolling back so her toes touch the floor.
"It loosens up my muscles," said Techler, who shrugs at the suggestion that she's flexible.
Gentle exercises like yoga and tai chi can be especially good for seniors because they build balance, which can help prevent falls, medical experts say.
"One of the main reasons why people become nonfunctional or even die is because of falls," said Dr. Fernando Branco, the medical director for the Rosomoff Comprehensive Rehabilitation Center and Brucker Biofeedback Center in Miami. "Those things can be catastrophic when you're 85. When you're 85 and you go into bed for several weeks or months because of a slow healing fracture, you're taking a lot of risks."
Yoga also has other benefits, he said.
In a study published by the National Institutes of Health in 2005, yoga was found to improve hip extension and increase stride length in a group of senior citizens who participated in the research.
"In general the idea that just because you are older you have less of a range of motion, that is really not correct," he said.