Exercise

Regular exercise or physical activity can do everyone a world of good. It helps prevent heart disease, diabetes, osteoporosis, and a host of other diseases, and is a key ingredient for losing weight or maintaining a healthy weight.

Exercise and weight control are also linked through the simple rule of energy balance: Weight change = calories in – calories out. If you burn as many calories as you take in each day, there's nothing left over for storage in fat cells, and weight remains the same. Eat more than you burn, though, and you end up adding fat and pounds. Regular exercise can help you control your weight, and it is key part of any weight-loss effort.

Despite all the good things going for it, only a minority of Americans get enough exercise or leisure-time physical activity to benefit. Only 30 percent of adult Americans get regular physical activity during their leisure time—and 40 percent of Americans get no leisure-time physical activity at all.

Body-Wide Benefits

Studies that have followed the health of large groups of people for many years, as well as short-term studies of the physiologic effects of exercise, all point in the same direction: A sedentary (inactive) lifestyle increases the chances of becoming overweight and developing a number of chronic diseases.

Exercise or regular physical activity helps many of the body's systems function better and keeps a host of diseases at bay. According to the landmark U.S. Surgeon General's report Physical Activity and Health regular physical activity:

• Improves your chances of living longer and living healthier
• Helps protect you from developing heart disease or its precursors, high blood pressure and high cholesterol
• Helps protect you from developing certain cancers, including colon and breast cancer
• Helps prevent type 2 diabetes (what was once called adult-onset diabetes), as well as its complications
• Helps prevent the insidious loss of bone known as osteoporosis
• Reduces the risk of falling among older adults
• Relieves symptoms of depression and anxiety and improves mood
• Controls weight

More recent observational studies also show that regular physical activity is associated with better cognitive function, lower risk of cognitive decline, and reduced risk of stroke.

The Cost of Inactivity

If exercise and regular physical activity benefit the body, a sedentary lifestyle does the opposite. According to analyses by a team from the Centers for Disease Control (CDC) and Prevention, inactivity was associated with more than 9 million cases of cardiovascular disease in 2001, at an estimated direct medical cost of nearly $24 billion.  Another CDC analysis suggests that because individuals who are physically active have significantly lower annual direct medical costs than those who are inactive, getting people to become more active could cut yearly medical costs in the U.S. by more than $70 billion.

Reaping the Benefits of Exercise

A wealth of studies has established the benefits of exercise. Yet two related— and very practical—questions remain: What is the best kind of exercise? And how much exercise do we need each day?

If you don't currently exercise and aren't very active during the day, any increase in exercise or physical activity is good for you. Aerobic physical activity—any activity that causes a noticeable increase in your heart rate—is especially beneficial for disease prevention. Some studies show that walking briskly for even one to two hours a week (15 to 20 minutes a day) starts to decrease the chances of having a heart attack or stroke, developing diabetes, or dying prematurely.

The American College of Sports Medicine and the American Heart Association recommend that healthy adults get a minimum of 30 minutes of moderate-intensity aerobic activity on five days each week, or get a minimum of 20 minutes of vigorous-intensity aerobic activity on three days of the week. You can do all 30 minutes at once or break it up into 10-minute periods. You can also combine moderate and vigorous exercise over the course of the week—say, by doing 20 minutes of more vigorous intensity activity on two days, and then doing 30 minutes of moderate intensity activity on two days.

Moderate-intensity aerobic activity is any activity that causes a slight but noticeable increase in breathing and heart rate. One way to gauge moderate activity is with the "talk test"—exercising hard enough to break a sweat but not so hard you can't comfortably carry on a conversation. Vigorous-intensity aerobic activity causes more rapid breathing and a greater increase in heart rate, but you should still be able to carry on a conversation—with shorter sentences.

For the average person, brisk walking fills the bill for moderate-intensity activity, while jogging is an example of vigorous-intensity activity. How fast is brisk? For the average person, it means walking three to four miles an hour, or about as fast as you'd walk if you were late for an important appointment. Keep in mind that what feels like moderate activity for one person may actually be very vigorous activity for another: A typical young marathon runner, for example, could walk at a 4-mile-per-hour pace without breaking a sweat. But this same pace would likely feel very vigorous for the typical 90-year-old person.

Walking is an ideal exercise for many people—it doesn't require any special equipment, can be done any time, any place, and at any pace, and is generally very safe. What's more, studies such as the Nurses' Health Study,   Health Professionals Follow-up Study,  Women's Health Study,  Harvard Alumni Health Study,  National Health Interview Survey, Women's Health Initiative,  Honolulu Heart Program, and others have demonstrated that this simple form of exercise substantially reduces the chances of developing heart disease, stroke, and diabetes in different populations.

If you don't like walking, any activity that makes your heart work harder will suffice, as long as you do it long enough and often enough.

More Activity Equals More Benefit

Keep in mind that 30 minutes of moderate-intensity aerobic activity a day is an excellent starting point, not an upper limit. Exercising longer, harder, or both can bring even greater health benefits. 

Feeling What's Right

The current recommendations for physical activity are general recommendations aimed at the general population. The problem with guidelines is that they try to cover as many people as possible. In other words, they aren't right for everyone. How much exercise you need depends on your genes, your diet, how much muscle and fat you carry on your frame, how fit you are, and your capacity for exercise.

A study of more 7,000 men who graduated from Harvard before 1950 suggests that older people, those who are out of shape, or those with disabilities may get as much benefit from 30 minutes of slower walking or other exercise as younger, more fit people get from the same amount of more-intense activity.

In other words, if an exercise or physical activity feels hard, then it is probably doing your heart—and the rest of you—some good, even if it doesn't fall into the "moderate" category. If you are currently not active at all, it may be daunting to start out with 30 minutes a day of activity, five days a week. So start with a shorter, less-intense bout of activity, and gradually increase over time until you can reach or exceed this goal. This "start slow, build up over time" advice for physical activity applies to everyone, but it's especially true for older adults, since starting slowly can help lower the risk of injury—and can make exercise more enjoyable.

Don't get stuck in a rut, though. As your body adapts to exercise, you'll need to push yourself more and more to get the same cardiovascular workout. Another way to know that it's time to pick up the pace is if you see your weight or waist size start creeping up on you.

Beyond the Heart 
 

When talking about the benefits of exercise, keeping the heart and blood vessels healthy usually gets most of the attention. For many individuals, though, stretching and strength training exercises that barely raise the heart rate— and so aren't considered moderate at all—may be just as important.

Resistance Training

Resistance training or weight training is probably the most neglected component of fitness programs but one of the most beneficial. In fact, it's so beneficial that the American College of Sports Medicine and the American Heart Association recommend that adults engage in resistance training at least twice a week, to improve muscle strength and endurance.(1)

To understand why strength training is so important to our overall fitness, it helps to understand a bit about body composition. Our body can basically be divided into two components. Fat mass consists of the body's fat store, while fat-free mass is a combination of non-fat tissue such as muscle, bone, internal organs, and so on. A significant part of fat-free mass is lean body mass, which is essentially muscle.

Muscle is metabolically active tissue. This means that it utilizes calories to work, repair, and refuel itself. Fat requires very few calories—it just kind of sits there. As we enter our mid to late twenties, we slowly start to lose muscle as part of the natural aging process. This means that the amount of calories we need each day starts to decrease, and it becomes easier to gain weight. By engaging in regular strength training exercise, it is possible to decrease this loss of lean muscle tissue and even replace some that has been lost already.

Studies have shown strength training to increase lean body mass, decrease fat mass, and increase resting metabolic rate (a measurement of the amount of calories burned per day), in younger and older adults.  While strength training on its own typically does not lead to weight loss, its beneficial effects on body composition may make it easier to manage one's weight and ultimately reduce the risk of disease, by slowing the gain of fat—especially abdominal fat.

Another beneficial effect of resistance training pertains to bone health. In addition to weight bearing cardiovascular exercise, weight training has been shown to help fight osteoporosis. For example, a recent study in postmenopausal women examined whether regular strength training and high-impact aerobics sessions would help prevent osteoporosis. Researchers found that the women who participated in at least two sessions a week for three years were able to preserve bone mineral density at the spine and hip; over the same time period, a sedentary control group showed bone mineral density losses of 2 to 8 percent. 

Finally, in older populations, resistance training can help maintain the ability to perform functional tasks such as walking, rising from a chair, climbing stairs, and even carrying one's own groceries. An emerging area of research suggests that muscular strength and fitness may also be important to reducing the risk of chronic disease and mortality, but more research is needed. 

Many people are intimidated by the idea of resistance training or are afraid of injury. They need not be. A great idea is to consult an expert. Consider hiring an exercise physiologist or personal trainer for a few sessions until you have the confidence to branch out on your own. For more information and to locate a trainer contact The American Council on Exercise.

Flexibility Training

Flexibility training or stretching exercise is another important part of overall fitness. While some recent studies have cast doubt on the benefits of stretching to reduce exercise-related muscle soreness and injury, flexibility training may help older adults preserve the range of motion they need to perform daily tasks and other physical activity.  The American Heart Association recommends that healthy adults engage in flexibility training two to three days per week, stretching major muscle and tendon groups.  For older adults, the American Heart Association and American College of Sports Medicine recommend two days a week of flexibility training, in sessions at least 10 minutes long. 

The Bottom Line: Tips for Getting Exercise into your Life

• Get off a stop or two earlier during your bus or subway commute; walk the rest of the way.
• Purposefully park your car a little further from the mall or store. It may not seem like much, but over weeks and months, these minutes of exercise add up.
• Use the stairs instead of elevators and escalators whenever possible.
• Consider buying a piece of cardiovascular equipment for your home (e.g. treadmill, bike, elliptical machine). Home models can be more reasonable than you think, and you can't beat the convenience.
• When you get busy, try to combine your cardiovascular exercise with something that you do already. Hop on that piece of home equipment while watching TV, reading the newspaper, or returning phone calls.
• Make it fun! Try a new sport like tennis or rollerblading. The more that you enjoy exercise, the more likely you are to stick to it.
• Make it social. Walk with a friend, your spouse, or your family in the morning or evening.
• Keep an exercise log. It will help to make you more accountable.
• Take a walk for 20 minutes of your lunch hour.
• Hire a personal trainer for a session or two to help you with your weight training and flexibility training. Then you'll have the confidence to branch out on your own.
• Set aside a specific time each day to exercise and put it in your planner.
• Set short-term goals—and reward yourself for achieving them. Try targeting a specific event, such as a road race or a walk-for-charity, to participate in—this can help keep you motivated. Choose fitness-focused rewards for reaching your goals, such as new workout gear or a heart rate monitor.