Is easy-does-it exercise enough?

How long and intensely you work out depends on your fitness goals...

Exercise slogans seem to change with the decade. In the 1980s it was "no pain, no gain," the idea being that you had to push yourself hard for exercise to do any good. In the 1990s the mantra changed to "every little bit helps," as public-health officials emphasized the benefits of moderate physical activity. Today there's a new prevailing message: "often and long--but not necessarily hard."

Which exercise prescription is right for you? That depends on what you want to accomplish. At a minimum, most people should aim for the basic health-preserving benefits of working out. For that goal, a little bit of exercise does indeed help a lot-though a lot of exercise may help some more. Longer, frequent workouts are best if losing weight is your goal. And if you want to tone your physique and hone your physical performance, vigorous workouts still provide the most "gain." But any "pain" that exceeds a mild muscle soreness means you're overdoing it and risking injuries.

Preventing disease

In the 1990s the national Centers for Disease Control and Prevention and the American College of Sports Medicine endorsed an exercise prescription focused on disease prevention. It set easy-to-reach activity goals that included walking, gardening, dancing, cleaning the house, and playing with the kids, as well as traditional workouts such as jogging and biking. Moreover, you didn't have to do your daily exercise in one session but could break it up into 10-minute chunks over the course of the day. That relaxed approach to exercise was part of a calculated effort to lure the growing legions of sedentary Americans off the couch. But the guidelines were more than a mere public-relations ploy. An increasing body of evidence backs up the effectiveness of those recommendations.

A modest dose of physical activity can translate into substantial health benefits, though the risk of heart disease, cancer, diabetes, and premature death decreases even further as the amount and intensity of exercise increases. For example, a September 2003 study of postmenopausal women found that those who walked for an average of just 1.25 to 2.5 hours per week had an 18 percent decreased risk of breast cancer compared with inactive women; those who exercised an average of 10 hours a week had further, but less dramatic, reductions.

The evidence that moderate-intensity exercise, even in short chunks, protects against disease is strongest for coronary heart disease, the most common killer of men and women. In an August 2000 study Harvard researcher I-Min Lee, M.D., Sc.D., found that brief bouts of physical activity offered as much coronary protection as extended workouts did, provided that individuals accumulated the same total amount of exercise. A follow-up March 2003 study confirmed that even moderate-intensity exercise helps. Intensity was measured by the exercisers' perceived exertion, not by an absolute scale based on, say, walking speed or exercise type. "What's moderate to one person may be vigorous-or easy-to you, depending on your starting fitness level," explains Dr. Lee. "What's important is that you pick a pace that feels at least moderate to you."

What to do: Aim for a combined total of at least 30 minutes of physical activity most days of the week. The pace should be brisk but not necessarily vigorous. (See chart, Judge for yourself: How hard are you exercising?) Walk, bike, swim, or perform other activities at level 3 or 4 or higher. And remember: For lasting results, make a long-term commitment to regular physical activity.

Losing weight

The Institute of Medicine and other public-health groups increased exercise recommendations in 2002 to an hour of moderate-paced activities every day. These workouts are longer and more frequent than the minimum needed for disease-preventing benefits because their goal is to combat the growing obesity problem in the U.S.

The harsh reality is that you have to burn a lot of calories to lose weight. Most overweight people can't sustain a vigorous pace long enough to expend many calories without exposing themselves to a risk of injury. So a better approach is to burn calories by working out at a moderate pace for an extended period of time.

Several studies confirm that this approach works. But they also suggest that people are more likely to reach-and maintain-the recommended hour or so of daily activity if they work up to that level gradually and if they build in support, such as exercising with friends or family members. Other research shows that, as with health benefits, you can accumulate those minutes in short chunks over the day. Sustained weight loss also usually requires eating fewer calories. If you cut calories dramatically, you may be able to reduce how long you have to work out.

What to do: Start with the minimum exercise prescription for health benefits and slowly increase your activity level until you're getting at least an hour of moderate-paced activity (3 to 5 on the perceived-exertion scale) almost daily.

Several strategies, in addition to exercising with a partner, can make this goal less daunting by making exercise more enjoyable, less tiring, or both:

• Squeeze short bouts of physical activity into your daily routine, and keep track of the amounts you're getting. Consider walking briskly at least part of the way to work, or taking the stairs rather than the elevator or escalator.



• Choose a variety of fun activities that are easy on the joints, such as brisk walking, in-line skating, biking, and dancing. Vary exercises from day to day to reduce fatigue by giving tired muscles a day off.



• Within a single gym session, switch off among different activities. For example, use a treadmill, then a rowing machine, and then a stationary bicycle so that you don't work any muscles to exhaustion.



• Consider investing in a home-exercise machine. A June 2003 Consumer Reports analysis found that treadmills are less likely to sit unused than other equipment, and some research suggests that they're particularly efficient calorie burners. Cross-country-skiing machines, elliptical exercisers, and stationary bikes with movable handlebars boost workouts by having you pump with your arms while your legs are working. Before you invest the $500 to more than $2,000 that such machines can cost, try them out. Check that controls are easy to use and that the machine feels sturdy and operates smoothly. Choose a machine you'll enjoy enough to keep using.

Boosting aerobic fitness

Aerobic (or cardiovascular) fitness is the ability of the heart and lungs to supply the muscles with enough oxygen at times of exertion. If you're fit, you won't get too winded or fatigued when you sprint hard to catch a bus or climb the stairs quickly. Anything that gets you moving faster or harder than you are accustomed to is likely to improve your fitness. But most research suggests that for substantial gains in aerobic fitness, you need a more vigorous pace than that recommended for health benefits or weight loss. Significant improvements can be gained by relatively short, vigorous workouts.

What to do: To boost aerobic fitness, aim for 20 minutes of vigorous exercise three days a week. But remember: Intensity is relative. Choose an activity that pushes you up to at least 4, and preferably 5 or 6, on the perceived-exertion scale (see chart, below). Avoid pushing above 7 if you're a beginning exerciser, or beyond 9 if you're more advanced.

For some beginning exercisers, even a slow walking pace may seem vigorous; for most people, fast walking provides sufficient exertion. An especially effective way to introduce vigorous exercises into your routine is through interval training, or alternating bursts of intense activity with periods of a more relaxed pace. Doing so prevents lactic acid, a waste product of muscular activity, from reaching levels that make exercise painful and exhausting. Beginning exercisers should generally switch between a 3 or 4 and a 5 or 6 on the perceived-exertion scale; advanced exercisers can go higher on the scale.

Low-impact options that avoid the joint-jarring effects of jogging or running include the following:

• Walking on a hilly terrain, and using weights to increase the challenge. Belts or vests with pockets to hold weights are the safest because they don't interfere with your walking mechanics, as ankle or wrist weights can.



• Using an exercise machine. On a treadmill, boost the incline and speed to reach the desired exertion. On other machines, use controls to increase the intensity of your workout as you become more fit.



• Doing low-impact aerobic dance or step aerobics, which involves stepping on and off a low bench while moving your arms, usually in time to music.

Building strength

Strength training can do more than just make you look better. It improves your ability to perform everyday tasks, such as carrying groceries and opening windows. Moreover, it's particularly effective at protecting your bones by warding off osteoporosis and preventing falls, and it may provide some of the same heart benefits as aerobic exercise.

As with aerobic exercise, a little strength training can go a long way.

What to do: Three 10-minute strength-training workouts a week provide maximum benefits for younger exercisers. But just two weekly sessions will still provide substantial benefits for them-and indeed are preferable for people over 60 or so, since older individuals need more time off to rest their muscles. How many sets of repetitions should you do for each muscle group? Just a single set is enough for most beginners. If you're after the sculpted-muscle look, two sets are nearly as effective as three, even for experienced exercisers.

Judge for yourself: How hard are you exercising?

Use the scale to approximate how intensely you're exercising. Is your effort weak, moderate, or almost as hard as you can possibly work? In general, people aiming for the basic disease-fighting and weight-loss benefits of exercise should aim for at least a 3 or 4 on the scale shown here; those wanting to boost their aerobic fitness should push a little harder.