Exercise can be defined as physical activity that involves planned, structured, and repetitive bodily movements for the purpose of maintaining or improving physical fitness and overall health. Exercise includes cardiovascular training, muscle-strength training, and stretching activities for flexibility and to prevent injury. Typical exercise activities include walking, running, cycling, swimming, weight training, aerobics, and individual and team sports.


Reasons for staying physically active vary from person to person. Many people exercise to lose weight and build muscle, maintain a healthy weight, or destress and rejuvenate after a long day. Whatever the reason, regular exercise is important for the physical, mental, and emotional health of people of all ages, from young children to the elderly. Exercise promotes:

The beneficial effects of exercise diminish within two weeks of substantially reducing physical activity. Physical fitness is lost completely if exercise is not resumed within two to eight months.


The National Institutes of Health (NIH) has identified inactivity as a major public health problem in the United States, and most North American adults would benefit from increasing their level of physical activity. More than 60% of American adults do not get enough physical activity to provide health benefits, and more than 25% are inactive during their leisure time. Lack of exercise is a major contributor to the current epidemic of obesity because people burn fewer calories than they take in, resulting in weight gain. Sedentary lifestyles and unhealthy eating patterns are responsible for at least 300,000 deaths from chronic disease each year in the United States. Likewise, a recent survey in the United Kingdom found that only one-third of adults meet recommended goals for physical activity.

JACK LALANNE (1914–2011)

Jack LaLanne grew up in California, first in the desert town of Bakersfield, then moving to Berkeley while he was still a child. His father's early death was caused in part by poor nutrition, and young Jack was addicted to sweets. Plagued by headaches, bulimia, and a nasty temper, LaLanne was labeled a troublemaker and had dropped out of school by age 14. That year he attended a lecture at the Oakland Women's City Club that changed his life. The subject of the lecture was health, nutrition, and the evils of meat and sugar, and LaLanne was, in his own evangelical words, “born again.” He changed his diet and began to work out daily. He went back to school, made the high school football team, and went on to college where he studied to become a chiropractor.


(Archive Photos/Getty Images)

Instead, Jack went on to open one of the nation's first fitness facilities in 1936. He broughtfitness into everyone's homes through his television show, The Jack Lalanne Show. The show ran for 34 years.

At the impressive age of 96, LaLanne died. He passed away at his California home on January 23, 2011, of respiratory failure from complications of pneumonia. NPR reported that LaLanne maintained an exercise routine until the end of his life. His advanced age was a testament to his message. In 2008 LaLanne was inducted into the California Hall of Fame of the California Museum.

As of 2016, about one in five (21%) adults meet the 2008 Physical Activity Guidelines, and less than three in 10 high school students get at least 60 minutes of physical activity every day, according to the Centers for Disease Control and Prevention (CDC). The CDC includes a department called the Division of Nutrition, Physical Activity, and Obesity (DNPAO), centering around new and innovative programs that focus on increasing physical activity and improving nutrition with a goal of a healthy weight and body mass index for individuals of all ages.

Insufficient exercise is more prevalent among women than men and among those with lower levels of economic stability and educational achievement. The number of adult Americans who are exercising regularly, however, is on the increase. According to the CDC, as of 2013, 50.2% of adults are aerobically active for at least 150 minutes per week and 31.2% for at least 300 minutes per week.


Exercise generally decreases with age. It is estimated that two-thirds of Americans over the age of 65 have at least one chronic condition, with 36 million having some form of arthritis. Lack of exercise is a significant contributor to conditions such as osteoarthritis, lower back pain, and osteoporosis. More than 300,000 total joint replacements are performed each year due to osteoarthritis.


Throughout most of human history, people were physically active on a regular basis and thus got plenty of exercise required for good health. Then, early in the twentieth century, the rate of heart attacks in Western countries began to increase dramatically. The first indication that this might be due to lack of exercise came in a landmark 1953 study of London bus conductors: conductors, who spent their days collecting fares from seated passengers and walking up and down the stairs of double-decker buses, had half the number of heart attacks as seated bus drivers. Since then, countless studies have confirmed the positive effects of exercise, not just on the heart and circulatory system, but on virtually every system of the body.


Chosen exercises should be interesting and appealing: studies have found people are more likely to stick with an exercise program when they enjoy the activity, whether as an individual, with a partner, or with a group or team. Convenience is another important consideration. Exercise can take place at home, outdoors, at a health club or fitness center, school, church, or community center. Taking a class, working out with a friend, competing, or setting personal goals can help maintain motivation. Walking for exercise can be combined with various enjoyable activities, such as bird watching, museum visits, window shopping, or exercising the dog. Group exercises and team sports are good ways to socialize. Varying exercise routines every few weeks can benefit different muscle groups and help prevent boredom. In addition, because the human body adjusts rapidly to most exercises, continuing the same routine for too long can result in decreased benefits.

The most efficient cardiovascular exercises for improving physical fitness include:

Other exercises that provide cardiovascular conditioning—but are less endurance-promoting because they usually require frequent starting and stopping—include:

Teenagers can get cardiovascular exercise through school sports, including:

People who are generally sedentary can still get exercise through their occupations, housework, home repair, gardening, using stairs instead of an elevator, and various recreational pursuits. People with health problems can find exercises that accommodate their injuries or conditions. The American Council on Exercise suggests specific exercises for the elderly and for adults with problems such as asthma, chronic pain, bad knees, shoulder injuries, arthritis, and flat feet.

Regularity, duration, and intensity are key elements of exercise. It has generally been recommended that adults get at least 30 minutes of moderate-intensity exercise on most days of the week, but the most recent consensus is to aim for 150 minutes per week, regardless of how it is divided up. The latest evidence suggests that three 10-minute bouts of exercise are as beneficial as one 30-minute workout. Improving cardiovascular endurance requires at least 20–60 minutes of cardiovascular exercise three to five days per week. The US Department of Health and Human Services recommends at least 60 minutes of physical activity for children and teens on most or all days of the week.


Exercise should begin with a light warm-up of 5–10 minutes that includes gentle stretching to loosen muscles and joints and help prevent injury. The warmup may involve slowly beginning the conditioning activity—warming up for a brisk walk or jog by walking slowly or strolling, or warming up to ride a stationary bike by pedaling slowly with no resistance. Warming up increases blood flow to the muscles, increases muscle temperature, and prepares muscles to work harder.


Aerobic exercises can be done outside of a formal setting, with little or no equipment. Because boredom is a frequent cause for stopping exercise, however, it can be beneficial to participate in exercise classes or join a gym or health club. Exercising with a group often helps with motivation. Also, most health clubs offer a variety of stationary aerobic equipment, such as bikes, treadmills, stair climbers, and rowing machines.

Equipment used for building muscle, strength training, and improving balance includes individual weights and weight-loaded machines. Exercise equipment should be checked to determine if it can bear the weight of people of all sizes and shapes.

It is important for people to be shown the proper form in any activity to avoid strain and possible injury, especially when using exercise equipment. People also should know what parts of the body might be stressed by a particular exercise. A person can agitate old injuries or create new ones by improperly using equipment or wearing inadequately cushioned shoes.

Training and conditioning

Exercise geared to a target heart rate is typically about 70% of the maximum heart rate for one's age. Heart rate is calculated by counting the pulse, usually about halfway through a 20–30-minute workout. Fingers are placed firmly, but lightly, over the inside of the wrist or on the neck just below the angle of the jaw; too much pressure on the neck, however, can slow down the heart rate. The palm can be placed over the heart to count the number of beats. A zero is added to a six-second count or a 10-second count is multiplied by six to obtain the beats per minute (bpm). Maximum bpm is calculated by subtracting one's age from 220. For example:

A bpm above the target rate indicates a need to slow down, whereas a bpm below the target indicates a need to speed up the pace of exercise.

Other methods for measuring the intensity of cardiovascular exercise include:

Aerobic exercise—
Any exercise that increases the body's oxygen consumption and improves the functioning of the cardiovascular and respiratory systems.
Exercise involving free movement without the aid of equipment.
A fat-soluble steroid alcohol (sterol) found in animal fats and oils and produced in the body from saturated fats. High cholesterol levels contribute to the development of cardiovascular disease.
A class of peptides in the brain that are produced during exercise and bind to opiate receptors, resulting in pleasant feelings and pain relief.
The ability to maintain either a specific force or power involving muscular contractions for an extended time.
Metabolic equivalent of task; MET—
The energy cost of a physical activity, measured as a multiple of the resting metabolic rate, which is defined as 3.5 mL of oxygen consumed per kilogram (kg) of body weight per minute, equivalent to 1 kilocalorie per kg per hour.
Excessive weight due to accumulation of fat, usually defined as a body mass index (BMI) of 30 or above or body weight greater than 30% above normal on standard height-weight tables.
Physical activity—
Any activity that involves moving the body and burning calories.
Physical fitness—
A combination of muscle strength, cardiovascular health, and flexibility that is usually attributed to regular exercise and good nutrition.
Inactivity and lack of exercise; a lifestyle that is a major risk factor for becoming overweight or obese and developing chronic diseases.
Stress test—
An electrocardiogram recorded before, during, and after a period of increasingly strenuous cardiovascular exercise, usually on a treadmill or stationary bicycle.
Target heart rate—
The heart rate, in beats per minute (bpm), that should be maintained during cardiovascular exercise by an individual of a given age.
Neutral fats; lipids formed from glycerol and fatty acids that circulate in the blood as lipoprotein. Elevated triglyceride levels contribute to the development of cardiovascular disease.


Exercise poses a risk of injury, particularly if exercises are inappropriate or improperly performed. Too much exercise can be as harmful as too little; overuse of certain muscles and joints can lead to problems such as tennis elbow or shin splints. High-intensity exercises, such as high-impact aerobics and jogging, are not recommended as frequently as in the past. Running, in particular, is hard on the knees and ankle joints, and there is a risk of sprained ankles and injuries from falls. About half of all regular runners and players of team sports suffer some type of musculoskeletal injury each year.

Inadequate rest increases the risk of stroke and circulatory problems. Injury or illness from overtraining is sometimes indicated by a high resting heart rate, sleeping difficulties, or exhaustion. The risk of a heart attack can rise as much as 100-fold for a completely unfit individual who suddenly undertakes vigorous exercise, such as jogging or shoveling snow. In contrast, a person who runs five times per week has a significantly lower risk of heart attack during vigorous exercise. The risk of heart attack subsides about half an hour after exercising and pales in comparison to the lifetime benefits of regular exercise.

Various medical conditions can affect exercise. For example, people with back problems should avoid exercises that require twisting or vigorous forward movements, such as aerobic dancing or rowing. People with spinal disk disease should avoid highimpact activities.

More than 30 million Americans undergo surgery each year. Each patient's surgical risk, complications, and outcome depend, at least in part, on his or her physical fitness: how well cardiovascular and pulmonary systems withstand the stress of anesthesia; how quickly bones and muscles recover after surgical procedures; and how well metabolic and immune systems respond to surgery and the risk of infection.

Most doctors encourage patients to become active as soon as possible following surgery. Aftercare is individualized, and patients may have limitations on physical activity; however, the goal is to return individuals to normal daily activities and exercise routines. Patients should ask for explicit guidelines concerning exercise.


Prior to starting a new exercise program, individuals should consult with their physicians and undergo physical examinations. Individuals who have not been active for a long time or those recovering from an illness may need to build strength before they can participate in cardiovascular exercise. Exercise intensity and duration should then increase gradually.

To help prevent injury, warming up before, and stretching after, exercise is very important. People should pace themselves and check their heart rate or otherwise judge their level of exertion. If exercising becomes strenuous or worse, it is important to slow the pace. Although some discomfort, such as aches or stiffness, are to be expected during the first few days of a new exercise, if pain interferes with the routine, it is important to stop the activity or get instruction on technique. Strenuous cardiovascular exercise should never be halted abruptly without a cool-down because blood that has concentrated in the working muscles can pool and cause dizziness or lightheadedness.

Cardiovascular exercise requires a healthy diet with plenty of vegetables. It is best to wait at least two hours after a full meal before exercising and about an hour after exercising before having a meal, although a small healthy snack before exercising can boost energy levels. It is important to drink enough fluid to replace water that is lost as sweat, but coffee, tea, colas, chocolate, or alcohol can cause the body to lose fluid.

Simple home exercises, such as using a balance board, can reduce the risk of recurrent sprained ankles. Taking a few days off from cardiovascular exercise every month can help rejuvenate the body.


Both maximum heart rate and cardiac output are lower in older adults, in part due to a decrease in the beta-adrenergic response. Older adults should have a stress test before embarking on a cardiovascular exercise program.

Pregnant or breastfeeding

Some types of exercise are inappropriate for pregnant women. Pregnant women are generally advised to consult their healthcare providers about their exercise routines.


Exercise offers many beneficial results and promotes:

Additional benefits of cardiovascular exercise include:

Regular exercise lowers the risk of a heart attack by 50%–80%. Exercise also has been shown to reduce the risk of:

Improved fitness in response to exercise appears to be genetically determined and to run in families. Some previously sedentary people show less improvement in fitness than would be expected following weeks of a vigorous exercise program, and about 10% show no improvement at all. Even those who show no improvement in fitness still respond to exercise with lowered blood pressure and cholesterol, improved insulin levels, and less abdominal fat.


Even individuals who are overweight or obese can become aerobically fit with exercise. Studies have found that the risk of dying is more closely related to lack of fitness than to being overweight. In fact, people who are fit, but obese, have a lower risk of dying from health complications than people who are unfit but of normal weight.



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American College of Sports Medicine, 401 W Michigan St., Indianapolis, IN, 46202-3233, (317) 6379200, Fax: (317) 634-7817, http://www.acsm.org .

American Heart Association, 7272 Greenville Ave., Dallas, TX, 75231, (800) 242-8721, http://www.americanheart.org .

Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA, 30329, (800) CDC-INFO (232-4636), cdcinfo@cdc.gov, http://www.cdc.gov .

National Institute of Arthritis and Musculoskeletal and Skin Diseases, 1 AMS Circle, Bethesda, MD, 20892-3675, (301) 495-4484, (877) 22-NIAMS (226-4267), Fax: (301) 718-6366, NIAMSinfo@mail.nih.gov, http://www.niams.nih.gov .

Margaret Alic, PhD
Revised by Laura Jean Cataldo, RN, EdD
Karl Finley

  This information is not a tool for self-diagnosis or a substitute for professional care.