Don't let injury set you back from your daily exercise routine. — Photo by Getty Images

En español | During 30 years of running and cycling I'd never suffered a serious injury. Then, last year, at age 52, I decided to enter a half-marathon. I bought new running shoes, doubled my mileage and, within a week, severely strained my Achilles tendon. I lost the entry fee, a month of training and my swagger. It was a valuable lesson.

Our bodies may change with age, but we don't need to trade the gym for the bridge table. In fact, new research shows that exercise can help prevent Alzheimer's, protect against stroke, increase life expectancy and even change our DNA so our muscles work more efficiently.

As we get older, though, we need to be smarter about exercise. Tendons, muscles, joints and reaction times change. We don't bounce back from injury as quickly. Fortunately, new science reveals that a few simple actions, done two or three times a week, can cut your risk of getting hurt. Choose the few that work best for you.

Warming up is key before beginning your exercise routine. — Illustration by Juliette Borda

1. Ease into exercise. One sure way to hurt yourself is to do too much, too soon. "You want to literally warm up your muscles, to raise their temperature before you stress them," says Katherine Coyner, M.D., an orthopedic surgeon at the University of Texas Southwestern Medical Center. If you're going to jog, start by walking. Playing tennis? Jog around the court a few times, then add eight to 10 jumping jacks.

Strengthen your lower back with squats. — Illustration by Juliette Borda

2. Embrace the squat. "The single best exercise to prevent injury and maintain leg and lower-back strength, especially as you get older, is the squat," says Stuart Phillips, Ph.D., a professor of kinesiology at McMaster University in Hamilton, Ontario. Stand with your feet shoulder-distance apart and squat, back straight, until your thighs are almost parallel to the ground; rise slowly. Repeat up to 20 times.

Build your core strength. — Illustration by Juliette Borda

3. Target the middle. The muscles in your core are the fulcrum around which all other muscles in your body pivot, says Coyner. Without a sturdy core, serving a tennis ball or even walking can strain outlying muscles. To build core strength, try the plank — a simple exercise that resembles a pushup (see illustration) — in which your forearms rest on the floor. Hold your core steady for 30 seconds, rest and repeat.

Master the flamingo balance. — Illustration by Juliette Borda

4. Play flamingo. "Equilibrium declines with age," says Vonda Wright, M.D., author of Fitness After 40. And wobbling can contribute to trips and sprained ankles. Increase your balance by standing on one leg a few times a day, she says. Hold for 20 seconds; switch legs. After mastering that, stand on a towel, to make the surface beneath your feet uneven. Then do the exercise with your eyes closed.

Next: Take care of your Achilles. »