Hermann's sensible buildup is exactly the sort of training Schoene recommends.

"I tell people to set long-term goals," he said. "Make them modest goals if you've been sedentary. Start easy, and build. Look six months ahead."

Even those who are already in shape need to be smart around playgrounds - "great places to get hurt," according to Schoene. He recommends some simple strengthening exercises to build stability and make falls less likely. Shoulder and hip injuries are common as people age, and can lead to permanent disability.

"The more stable one is and the more basic strength one has, the less likely one is to have loss of balance," Schoene said.

Also, it's important to temper your competitive instincts — a lesson 64-year-old Roger Johnson of St. Paul, Minn., learned from his grandsons last summer.

Alex, then 7, asked his speedy grandfather to chase him on a jungle gym.

"I can still run faster than they can, but they are far more nimble...," Johnson said. "So I said, 'It is not fun for me to chase you on the apparatus because I can never catch you."'

"Alex said, 'But Grampy, that's not the point. Grampys are supposed to chase their grandkids so that THEY can have fun."'

Fitness can also help speed recovery. My mother rehabbed her ankle and added water aerobics to her fitness routine, which also involved stationary biking, walking, stretching and weight training. She expects that list will soon include chasing grandchildren again.

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Try these at-home preventive exercises

These at-home preventive exercises can give you more stability at the playground. Do them with a spouse or in a gym when possible; it's easier to keep up the routine if you do it with others.

Half squats:

Bend legs at knees and hips, lower torso until upper legs are parallel to the ground, then return to standing. Add resistance by holding phone books or tomato cans. Benefits: flexes Achilles tendon, strengthens calves and rear, requires balance, and develops trunk muscles, including obliques, abdominals and lower back.

Lateral arm raises:

Stand with feet slightly apart, arms at your side, palms facing in. Raise arms to head level, hold and lower. Add resistance with cans of vegetables. Benefits: Strengthens shoulder girdle, trunk, quad, rear.

Source: Dr. Robert Schoene, professor at the University of California-San Diego School of Medicine.