When Hillary Clinton fell boarding a plane two years ago in Yemen, it was a tumble watched around the world, with the secretary of state's spill preserved forever on YouTube.

The rest of us do our stumbling in relative privacy, but Clinton certainly is not alone in suddenly finding herself going down.

Falls are the second most common injury accident, after motor vehicle accidents. While often thought of as more of an aging hazard as bones become brittle and joints and tendons less pliable, a bad fall can hurt bodies at any age. The best prevention is to work on simple balance, a necessary skill whether you're kicking a soccer ball, carrying groceries or turning to wave from airplane steps.

Fitness experts say it's never too early or late to improve balance. Many exercise regimens incorporate balance training including Pilates, yoga, tai chi, dance and martial arts. You can also practice balance by sitting on a stability ball or by standing on one leg while you brush your teeth.

Start young, said Beverley Combs, who teaches strength and stretch classes at the Santa Rosa YMCA to students ranging in age from 30 to 90.

"You can't wait until you're 60 or 70 and fall over and break your hip," Combs said. "You can learn balance at any age."

Of course, that won't keep you from tripping on a tree root in your hiking boots.

"You can do all the good stuff to get strong and you could still fall," she said. But depending on your bone strength, you might bounce and not break. And if you work to get good core strength, you may right yourself before you hit the ground.

The three elements of balance are the auditory system, the sensory nerves called proprioceptors that are in muscles, tendons and joints, and the visual system.

"The inner ear is like a carpenter's level," said Darcie Fellows, who owns Santa Rosa Gymnastics and teaches step aerobics at the Y. "If we get a cold and it affects our inner ear, our level doesn't work."

If the muscles aren't responsive enough to signal the central nervous system about spatial awareness and body posture, "you don't have good body control," she said. "That's what happens when people say they couldn't catch their balance in time."

Your eyes figure into balance because they send signals to the brain about body position.

"You can have balance if two of the three are strong," Fellows said. "But if you lack two and only one is strong, you're taking chances. You have an older person having trouble seeing and then he gets a cold, down he goes. It's like a vertigo."

Balance problems, she said, can hit at any age — with weight gain, injuries, poor posture, illness, growth spurts and hormonal changes.

"You see someone who is physically fit, but she gets a cold or her knee is bothering her or she's put on 10 pounds or lost 10 pounds, and she's more at risk," Fellows said. "Suddenly she falls going upstairs or slips off the curb."

Growing children also have balance issues.

"They're the gangly kids who lose awareness and feeling in their body and stumble. The klutzy ones," Fellows said. "My daughter's feet got to size 7? when she was 12, and for about a year she was tripping on everything until her body grew to catch up to her feet."

And with toddlers, she said, "Their head is so heavy, they're always falling."

To test your balance, Fellows said, hold on to the wall or a chair, lift one foot off the floor and move it in different directions — side, back, front.

"And then do it with your eyes closed," she added.

Among people age 65 and older, falls are the leading cause of both fatal and nonfatal injuries, according to the Centers for Disease Control and Prevention.

Physical therapist Mary Chamberlain at Kaiser Santa Rosa said many falling hazards lurk in the home.

"Get rid of those piles of stuff on the living room floor," she said. Secure throw rugs. Add more lights.

Kaiser Santa Rosa holds a weekly fall-prevention class, open to the public, and a balance class. Sonoma County Area Agency on Aging offers mobility classes for seniors through its Matter of Balance program.

"Movement helps keeps your joints lubricated, and walking, running, any impact activity creates bone density," Fellows said. These activities boost balance as well.

But you can also just stand there.

"Go stand in the middle of room with your arms out at your side," she said, "and you're working your balance."

<i>Susan Swartz is a freelance writer and author based in Sonoma County. Contact her at susan@juicytomatoes.com.</i>