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Exercise your right to health

Exercise your right to health

Don’t let inconsistent guidelines on how much or what kind of exercise is best for your heart keep you seated in frustration.

(This article was first printed in the July 2004 issue of the Harvard Heart Letter. For more information or to order, please go to http://www.health.harvard.edu/heart.)

There isn’t an official “best” way to exercise if you want to control or prevent heart disease. And sometimes it seems as though there aren’t even consistent recommendations for how much to exercise.

For years, exercise was supposed to be hard: a no-pain-no-gain regimen of high-intensity activity aimed at pushing the heart and lungs to their limits. Then, in 1995, experts unveiled a kinder, gentler approach: 30 minutes or more of moderate-intensity activity done on most, preferably all, days of the week. Brisk walking and leaf-raking joined jogging and swimming as acceptable activities. With this no-sweat version, you don’t even have to be active for 30 minutes straight — 10- and 15-minute segments are fine. The emphasis on moderate activity was aimed, in part, at helping people who wouldn’t exercise vigorously harvest the health benefits of regular activity. But just as we were getting used to the idea of moderate exercise, the Institute of Medicine told us we needed 60 minutes a day of vigorous physical activity.

Which one is it — 30 or 60 minutes? Moderate or vigorous activity? Here are some exercise basics that we hope will clear the air and help you pick an exercise or activity that’s right for you.

How many steps to good health?

Can a device designed by Leonardo da Vinci matched with an easy-to-remember goal keep you fit and healthy?

One of da Vinci’s many inventions was a simple, pendulum-powered device for counting steps. Its electronic descendants, called pedometers, are now featured in programs sporting the 10,000 Steps a Day slogan. They are being promoted by government and public health officials. Even McDonald’s is getting into the act by offering a pedometer with its new “Go Active! Happy Meal.”

Pedometers are small, pager-sized devices that clock every step you take when clipped to a belt or pocket. Some let you program in the length of your average step in order to measure how far you’ve walked. Others tally up “aerobic steps”— continuous steps taken for more than 10 minutes at a stretch.

Pedometers are inexpensive ($5–$40), easy to use, and give you useful information about yourself. Wearing one for a week or so can help you get a handle on how active you are. Once you’ve figured out your average daily steps, the device can help motivate you to take more.

Should you aim for 10,000 steps a day? Not necessarily. That’s too high a goal, at least initially, if you aren’t used to walking or have a chronic condition that limits your activity. Several small studies show that some people who take 10,000 steps a day don’t move fast enough to meet the 30 minutes of moderate activity goal, while some exercisers who more than meet the goal never rack up 10,000 steps.

In other words, the quality of your steps, not the quantity, is what’s important. Walking briskly for at least 30 minutes a day, either in a single stretch or two or three shorter ones, will do more for your heart, lungs, and the rest of you than taking 10,000 leisurely steps.

Resolving the conflict

Let’s tackle the time and intensity questions first. The 1995 recommendation, which has been endorsed by the Surgeon General, American College of Sports Medicine, American Heart Association, and other groups, still stands as an excellent starting point for warding off a heart attack, stroke, or premature death. If you already have heart disease, it’s a great way to fortify your heart against future trouble.

The Institute of Medicine’s recommendation rightfully acknowledges that 60 minutes of exercise a day is better than 30 minutes. What’s more, the Institute focused on losing weight or maintaining a healthy weight, both of which require burning extra calories.

Calories burned are the key

If you aren’t active at all, any amount of exercise or physical activity is a step in the right direction. A walk around the block, even if you need to stop a few times to catch your breath, trumps sitting by a long shot. Climbing the stairs beats taking the escalator at the mall or at work.

If you’re already somewhat active, the more exercise you get, the better. A landmark study of 17,000 Harvard alumni suggests that men who burn an extra 700 or so calories a week by walking, playing sports, or doing some other form of dynamic exercise live longer than those who aren’t active (see Harvard Alumni Study below). The health benefits continue to increase up to about 2,000 or so calories a week, then seem to level off from there. Information from a long-term study of female nurses shows similar trends for women.

Harvard Alumni Study

A long-term study of Harvard graduates showed better survival with burning about 2,000 calories a week, the equivalent of walking 3 miles a day.

Tallying up calories burned isn’t something you can do on the fly. It depends on your weight, the intensity of an activity, and how long you do it. Here are a few benchmarks, all given for a 155-pound person:

• Walking briskly (at 4 miles per hour) for 30 minutes burns 150 calories.

• Heavy cleaning for 45 minutes burns 250 calories.

• An hour of singles tennis burns 300 calories.

We’ve posted a much longer list for three different weights on our Web site, health.harvard.edu/heartextra.

A word of caution here: Intensity matters. Sauntering through the mall for 15 minutes beats sitting, but it doesn’t make the grade as exercise for anyone who is active. For an activity to help your cardiovascular system, it must make your heart beat faster and speed up your breathing.

Exercise or activity

What’s the difference between physical activity and exercise? Both involve three Ms: movement, muscles, and metabolism. Physical activity is any movement that involves muscle contractions and an increase in metabolism. It includes everything from housework to marathon running. Exercise is a specific kind of physical activity — one done purposely to improve health and physical fitness.

Vary the dimensions

You can hit a target such as 2,000 calories a week many different ways. Adjusting the three dimensions of exercise — intensity, duration, and frequency — lets you pick activities that suit your lifestyle and personality. Intensity is how hard you exercise. It’s measured in calories burned per minute. Duration refers to how long you exercise, while frequency refers to how often.

Brief sessions of an intense activity (vigorous activity) can burn the same number of calories as longer or more frequent sessions of a less intense one (moderate activity). Say you prefer to keep your bouts of exercise short and sweet. A high-intensity activity such as tennis or vigorous cycling might be right for you. If intense isn’t your thing, pick a less vigorous activity that you can do more often or for longer periods. Many examples are posted at health.harvard.edu/heartextra.

Topple your exercise barriers

It’s one thing to say, “Just do it.” It’s another to actually get moving. Cars, labor-saving devices, televisions, and other machines and gadgets — even the design and layout of our communities — can subvert the need for muscle power and seduce us into sitting rather than moving.

Personal barriers also limit activity. These range from lack of time for exercise to worries that exercise will cause a heart attack or injury and limited access to parks, sidewalks, bicycle trails, or safe and pleasant walking paths.

If you want to exercise but have trouble getting started or sticking with it, try taking the “Barriers to Being Active” quiz from the National Center for Chronic Disease Prevention and Health Promotion. It can help you identify some of the things standing in your way.

Surmounting barriers such as lack of time or disliking exercise takes creative thinking about making time for physical activity and finding an activity you can enjoy. Dealing with other issues, like worrying that exercise will give you a heart attack, takes some education. Barriers like not having access to safe walking paths or exercise facilities may call for downright social activism.

You don’t have to leap the barriers standing between you and a more active life. Instead, try putting one foot in front of the other and walking around them.

Options for exercise

Many exercise recommendations emphasize walking. And why not? It’s free, easy, doesn’t require special training or equipment, and can be done anytime and anywhere. Plus dozens of studies show that walking can prevent or help control high blood pressure, high cholesterol, heart disease, diabetes, peripheral artery disease, heart failure, and a host of other conditions. As a bonus, walking is a weight-bearing exercise that can help prevent osteoporosis.

More interested in sports than walking? Tennis is a good option. In addition to being an aerobic sport that gives your heart and lungs a workout, it can be played at many different levels and well into old age.

If you’d rather get your exercise in a club, you’ll burn the most calories on a treadmill. Stair-steppers, rowing machines, and cross-country trainers come next, all ahead of the standard stationary bicycle.

Aim to burn an extra 2,000 calories a week. It doesn’t really matter how, as long as you find something other than your true love that moves you and gets your heart beating faster.