How to add years to your life

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Although becoming more active can improve your overall health, it won’t necessarily make you physically fit. To achieve your optimal fitness level—to function at your physiological best—you should follow the recommendations of the American College of Sports Medicine and regularly engage in both aerobic activities for the cardiovascular system and strength-training exercises for the muscles. Aerobic activities should be performed for 20 to 60 minutes three to five times a week; strength workouts, two to three times a week.

In addition to producing more health benefits, only vigorous exercises (defined as any activity that raises metabolic rate to six times or more above the resting rate) offers an added reward: a longer life. In a 1995 study that followed 17,300 men for more than 20 years, those who burned up 1500 calories in vigorous exercise—the equivalent of walking briskly or jogging for about 15 miles a week—had a 25% lower death rate than those who expended fewer than 150 calories a week. The more active the men were—up to an activity level of 3000 calories a week—the longer they were likely to live. Smoking history, body weight, and age did not affect the relationship between physical activity and risk of death.

To exercise at a vigorous enough level to burn up 1500 calories a week, you could:

• Walk at a rate of 3 to 4 miles an hour five times a week.
• Jog at a rate of 6 to 7 miles an hour for 3 hours a week.
• Cycle for an hour four times a week.
• Swim laps for 3 hours a week.

Because variety is the spice of life, many people prefer different forms of aerobic exercise. All can provide many health benefits. Among the popular options:

• Swimming: Your heart will beat more slowly in water than on hand, so your heart rate while swimming is not an accurate guide to exercise intensity. You should try to keep up a steady pace that’s fast enough to make you feel pleasantly tired, but not completely exhausted, by the time you get out of the pool.
• Cycling: Bicycling, indoors and out, can be as excellent cardiovascular conditioner, as well as an effective way to control weight—provided you aren’t just along for the ride. To gain aerobic benefits, mountain bikers have to work hard enough to raise their heart rates to their target zone and keep up that intensity for at least 20 minutes.