Your Guide to Exercising Through the Ages

These few simple fitness investments will last you a lifetime.

man running on a treadmill
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40s: Preserve strength, fight belly fat. Done raising young kids and settled into jobs with extended desk time, many 40-somethings stop lifting weights (or kids) just when it should be the opposite. Peeke explains that at 40, a man's testosterone starts to drop, and with it roughly 5 to 8 percent of his muscle mass per decade. Women also begin losing muscle more rapidly in their 40s. To keep your metabolic rate high and continue burning calories optimally, you need to work to preserve that lean muscle mass.

Another biological disadvantage to watch for is "stress fat," which burrows deep inside around the organs, putting you at risk of heart disease, diabetes, and cancer. "Up to the age of 40, sex hormones tend to protect you from getting too much fat inside the belly," Peeke explains. "A woman's estrogen will keep fat in the hips, thighs, and buttock, while a man's fat typically goes outside the belly, not deep in." But at 40, all bets are off. Chronic stress can also lower sex hormones and elevate the stress hormone cortisol, both of which lead to the buildup of this so-called "visceral" fat. Be very careful, Peeke says: "You can stay the same size but with fat redistribution" and not realize you're packing the pounds deeper. A consistent exercise regimen will help you keep fat gain, stress, and stress-eating in check.

50s: Protect your heart and core. No matter how active you've been, aches and pains will start to crop up now, Peeke says, and you'll have to adapt your exercise regimen around them. Sore knees? Stop running and find a pool, she says.

You'll also have to fight your body's tendency to curve forward in your 50s, which can cause chronic back pain and give you a "dowager's hump." Peeke recommends yoga and pilates for strengthening your abs and back, or "core." And don't slouch while you're walking—extend your body. This simple change can make a big difference in your spinal alignment.

The American Heart Association (AHA) recommends 30 minutes of aerobic activity five times per week to preserve heart health as you age. Since you'll start to need more recovery time from vigorous workouts in your 50s, Knopf suggests exercising with mild to moderate exertion instead. It's just as effective, he says, and you can do it every day of the week because you won't be sidelined by extreme fatigue or muscle soreness.

60s: Focus on prevention. Are you exercising regularly? Good—you're less likely to die prematurely from a chronic condition such as diabetes or heart disease, the AHA says. Staying strong through your 60s will also improve your odds of surviving a fall, which the Centers for Disease Control and Prevention pegs as a high risk once you hit 65. Recent research found that women in their 60s and 70s face as much as five times the risk of death within a year of suffering a hip fracture. Strong muscles and bones and good balance can help you avoid taking a tumble.

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You should be lifting weights at least once, but ideally two to three times per week for 30 minutes, alternating sessions of upper body exercises and lower body exercises. A simple resistance regimen can be enough to keep you from "the slippery slope of frailty," from which there's no coming back, Peeke says.

However Peeke doesn't recommend going it alone. In your 60s, your bones become more fragile and "your tendons and ligaments are drier," so she strongly advises working with a certified fitness professional specializing in geriatric exercise to help you avoid getting hurt. IDEA Fitness Connect, an extensive online database of certified fitness professionals, can help you find one near you.

Better yet, join a group fitness class; many gyms and community centers offer a variety of group classes geared toward seniors, such as Zumba and water aerobics. The supervision makes it safe and you may find working out with others more enjoyable, Peeke says.

70s+: Sustain strength and flexibility. Walking isn't the only activity that's safe for seniors 70 and up. To continue performing daily functions independently, Knopf says you must also continue to work on strength, flexibility, and balance.