Yoga exercises "move each joint in the body through its full range of motion--stretching, strengthening and balancing each part," she says. "A regular yoga practice can help prevent and relieve. . .health problems associated with age."

Francina, 48, has been working with seniors since age 14, when she began assisting elderly neighbors with errands, cooking and other chores so they could remain independent. "I befriended and cared for many of these same people until they died, some for as long as 25 years," she says. "I often spent 24 hours a day with people who were in wheelchairs and bedridden, so I was directly exposed to what happens when people stopped being active."

In the early 1970s, Francina began studying yoga with a 65-year-old neighbor and a variety of older teachers (including an 84-year-old man) who were "considered back then eccentric senior citizen types," she recalls. "Here were these vital people with beautiful posture, who were the same age as some of the frail people I took care of.

"The contrast was striking. It made me realize that we live in a chair-and-car culture, and the cold reality is that people who don't use their legs lose them."

When one of her teachers moved away, Francina took over teaching her yoga class at a retirement home, and discovered that, over time, even students in their eighties and nineties could grow stronger and more flexible. "As a teacher, I find it a continual revelation to see how the bodies of people of all ages respond to yoga and proper exercise," she writes in her book, "The New Yoga for People Over 50."