Karen Beck used to walk with her eyes on the ground, watching for every little bump.

Karen Beck used to walk with her eyes on the ground, watching for every little bump.

People with good knees stroll through life looking out at the world, with scarcely a thought about how their joints twist and turn with every step. Beck's knees — both of them — were shot, so unstable that walking on anything but a perfectly flat surface was simply too painful.

"The slightest change in a sidewalk or step — the pain was excruciating," she recalls.

When we're young, pads of cartilage where the leg bones meet in the knee allow the joint to move smoothly and painlessly, and we pay no attention to how wonderfully it all works as long as nothing hurts. When the cartilage disappears, whether from injury or years of wear and tear, the bones slip and grind across each other, and even the most ordinary bending or flexing can produce startling pain.

After years of misery, Beck, a retired Medford banker, finally had knee replacement surgery on both legs. The surgery is no picnic, and the recovery takes months, so surgeons typically don't do both knees at the same time. Beck scheduled her two surgeries six months apart to give her body time to recover. As she worked to regain full use of her legs, a friend encouraged her to take a class based on the Chinese martial art of tai chi.

The friend, Barbara Meredith of Medford, happened to teach the class at the Rogue Valley Family YMCA. She shows her students how to use slow-motion movements taken from tai chi to build muscle and improve balance. The class was designed specifically to help older people learn how to avoid falling, but Meredith thought the exercises would help her friend, too.

Beck started the twice-a-week class back in the dead of winter. Some five months later, she says she feels the difference where it counts.

"It really helped strengthen my knees," Beck says. "I don't have to look down anymore at every step I'm taking."

Like other Asian martial arts, tai chi's origins are lost in time. Some legends date it back to the 1200s, and variations on the basic form have been documented back to the 16th century. In America, we mostly know the ultra-slow style, which gives participants time to think through each aspect of the simplest movements, such as taking a step.

"The thing that's so wonderful about tai chi is getting (body parts) aligned," Meredith, the instructor, explains. "You turn so the foot, ankle, knee and hip are all in line before you put your weight down."

Beck, who's 65 now, likes the combination of mind and body awareness that she's learned by doing the movements.

"What I really love is the coordination and the thinking about it," she says. "I want to challenge my mind and body."

The class Meredith teaches was developed by Fuzhong Li, of the Oregon Research Institute in Eugene. Li studied in China and earned a Ph.D. in exercise science from Oregon State University. He took some basic movements from classical tai chi forms and taught them to people who had Parkinson's disease. In a randomized study, those who had learned movements based on tai chi suffered fewer falls than Parkinson's patients who did not study the movements.

Li published his research in the New England Journal of Medicine. The program he developed is called "Tai Chi Moving for Better Balance" to differentiate it from tai chi proper.

Meredith says the Y's national organization won a grant from the federal Centers for Disease Control and Prevention to implement the class at YMCAs across the United States. A retired kindergarten teacher, she's one of just seven trainers who travel to local Ys to teach the class to other instructors.

"I never dreamed I'd be teaching 65-year-olds instead of 6-year-olds," she says, laughing.

Beck believes the awareness she gained in class has saved her from at least one nasty fall.

There's a technique to avoiding a fall, she says. "Instead of putting your arms out (to break the fall) you take a step. You bend your knees and step out with your foot. It's kind of like relearning how to walk.

"I tripped the other day and I caught myself," she says. "I honestly don't know if I would have caught myself before (taking the class)."

She says she feels stronger and more secure after practicing the moves, and her fear of falling has shrunk as her confidence has grown. On a recent weekend, she walked to the top of Upper Table Rock, on a trail with plenty of loose stones, protruding rocks and assorted foot-grabbers.

"I wouldn't mind doing it again," she says.

Bill Kettler is a freelance writer living in Rogue River. Reach him at bdkettler@gmail.com.