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Commentary: Exercise is Medicine

Harold Elrick, MD


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In Brief: Exercise is becoming more widely used to prevent and treat the diseases that are most prevalent in the United States: coronary artery disease, stroke, hypertension, diabetes, arthritis, osteoporosis, dyslipidemia, obesity, depression, cancer, and chronic obstructive pulmonary disease. However, physicians need more training in how to make best use of this powerful therapy. Physicians can successfully encourage activity by giving patients a written exercise prescription along with printed advice on how to design a safe, enjoyable routine.

Exercise is a medicine that can prevent or treat many disabling or fatal diseases. Seventy percent of deaths (1.5 million) each year in the United States are from eight killers: heart disease, cancer, stroke, hypertension, chronic obstructive pulmonary disease (COPD), diabetes, and osteoporosis (1). Other diseases treatable with exercise—obesity, arthritis, depression, and dyslipidemia—contribute considerably to disability and premature death.

Prescription Parallels

When we think of "medicine," we often think of a drug, something to be taken by mouth or injection. Although not "taken" but "done," an exercise prescription is much like a drug prescription (table 1). A large and growing body of clinical and epidemiologic evidence supports the concept that specifically prescribed exercise is highly effective as treatment and prevention for the above-cited diseases as well as for health enhancement (2).

Table 1. Comparison Between Exercise Therapy and Drug Therapy
Parameter Exercise Drugs
Type Aerobic, anaerobic, stretch, relaxation, flexibility, coordination, toning Antibiotics, analgesics, anti-inflammatories, sedatives, antidepressants, hormones
Frequency 1-3 times/day, 7 days/week 1-3 times/day, 7 days/week
Duration Lifetime Short-term or lifetime
Time of day Various Various
Contraindications Illness, pain Allergy, rash, polypharmacy, other diseases
Side effects Overuse injuries to muscles, tendons, or ligaments; joint injury; fatigue Organ damage, anemia, gastrointestinal symptoms, drowsiness, etc.
Patient education Required Required
Compliance Variable Variable

The health rewards of exercise extend far beyond its benefits for specific diseases. Exercise reduces blood clotting, enhances self-image, elevates mood, reduces stress, improves appearance, increases energy, gives the feeling of well-being (probably by stimulating endorphins). It reinforces other positive life-style changes, such as healthier eating habits and smoking cessation (2). It also stimulates creative thinking (4).

Furthermore, the ability of exercise to restore function to organs, muscles, joints, and bones is not shared by drugs or surgery. Paradoxically, conventional medical practice favors physical rest and inactivity during recovery from illness.

Medical students spend a year learning about pharmacology and receive instruction on drug prescribing throughout their training. Often, the drugs they study will no longer be recommended by the time they are in practice. On the other hand, medical students are not instructed on how to prescribe exercise—the best medicine of all. (See Patient Adviser "Exercise—the Best Prescription," and prescription form.)

Exercise Benefit Specifics

Let us examine the benefits of exercise therapy for the common serious diseases.

Coronary artery disease (5-9). Coronary artery disease (CAD) is the number one killer, responsible for 2,000 deaths in the United States each day. CAD claims many people who are at the peak of their career. About twice as many heart attacks occur every day.

Exercise combined with diet therapy can reverse established heart disease. Furthermore, exercise improves heart function, reduces several coronary risk factors (hypertension, high cholesterol, low high-density lipoprotein (HDL) cholesterol, and obesity), enhances psychosocial well-being after a heart attack and in general, and improves survival.

In summary, exercise is an effective strategy for preventing heart disease, and it is a beneficial, low-cost, pleasure-giving treatment without the side effects of drugs or the risks, pain, and expense of surgery.

Cerebrovascular disease (10-12). Vigorous exercise in early adulthood confers considerable protection from strokes in later life. This effect is independent of other risk factors. Furthermore, exercise is essential for restoring function following a stroke—again, a benefit not shared by drugs or surgery.

Hypertension (13-17). Substantial evidence shows that exercise is an effective treatment for mild and moderate high blood pressure and is a useful adjunct for the treatment of severe hypertension. Many patients who adhere to a regular, specifically prescribed aerobic exercise program can reduce their blood pressure without taking drugs. Thus, they avoid the potentially toxic effects and considerable expense of long-term drug therapy. Drug and exercise compliance are reported to be similar. Postexercise blood pressure reduction in normal and hypertensive patients disappears 2 weeks after exercise stops.

The degree of blood pressure reduction depends on the type, duration, and intensity of the exercise, as well an individual's genetics. Therefore, the prescription must be carefully individualized. Among nonpharmacologic means for lowering blood pressure, physical activity provides better patient compliance and quicker results than weight reduction or alcohol and salt restriction. (See "Management of Hypertension: Adapting New Guidelines for Active Patients," February 1995, page 47.)

Diabetes (18-20). Exercise can prevent or delay the serious complications of diabetes, namely, the vascular disease of the brain, heart, kidney, eyes, and legs that commonly occurs in diabetics who are under age 40. The same benefits of exercise are seen in those who develop the disease in later life. (See "Managing Activity in Patients Who Have Diabetes: Practical Ways to Incorporate Exercise Into Lifestyle," March 1995, page 41.)

Exercise improves the abnormal blood lipid pattern and reduces the high blood pressure common in people who have diabetes. In addition, exercise increases insulin effectiveness and the metabolism of sugar, thereby reducing the insulin requirement, which in turn reduces the risk of vascular disease. (High blood insulin has been implicated in the pathogenesis of arteriosclerosis.)

The complexity of diabetes treatment requires a combination of methods to achieve healthy blood sugar levels and to prevent or reduce the serious complications of the disease. An exercise regimen, properly taught and followed, helps accomplish this goal and allows diabetic patients to lead healthy, active lives.

Arthritis (21-24). In patients who have rheumatoid or degenerative arthritis, exercise improves endurance, strengthens muscles, and increases joint flexibility and range of motion. These, of course, are benefits that drugs or surgery cannot achieve.

Osteoporosis (25-27). Osteoporosis affects 20 to 24 million postmenopausal American women and an unknown number of men over the age of 80. It results in musculoskeletal weakness, loss of height, bone fractures (primarily spine and hip), and painful disability. A quarter million hip fractures occur each year in the United States, resulting in 12,000 deaths and $11 billion in medical expenditures. However, research indicates that regular exercise can prevent and control the disease.

Dyslipidemia (28-30). Abnormalities of blood fats (high total cholesterol and triglycerides and low HDL cholesterol) are major risk factors for vascular disease of the heart, brain, kidney, eyes, and legs. Regular exercise reduces total cholesterol and triglyceride levels and raises HDL cholesterol.

Obesity (31-34). Amount of body fat is a useful indicator of health and fitness, as well as an early warning signal of many serious diseases. Excess body fat is a risk factor for heart disease, hypertension, diabetes, many cancers (breast, prostate, colon, uterus, and gall bladder), and premature death from other causes. It appears that being overweight aggravates a very wide spectrum of diseases and is also a handicap to getting a job, obtaining admission to a university, and forming social relationships.

The magnitude of the problem in the United States is perhaps greater than in any other country. Estimates of the number of overweight Americans range from 50 million to 200 million. The average American is said to have 20 to 30 lb of excess body fat. Daily, lifelong exercise is an essential strategy for achieving and maintaining optimal weight. Diet, though essential, cannot be relied on alone for successful weight loss and maintenance.

Depression (35-37). Depression, the most common mental disorder, affects approximately 5% (about 12 million) of Americans at any given time. Psychologists have observed that walking or running has both physiologic and psychological benefits for people who are depressed. These forms of exercise reduce depression and anxiety, increase feelings of well-being, improve tolerance to everyday stress, and improve the self-image of depressed patients. It is difficult to sustain depressed feelings while one is physically exerting. Furthermore, exercise stimulates the release of the "feel good" hormones (endorphins).

One report (36) concluded that walking or running while talking with depressed patients was more effective than talking and listening to them in an office because (1) the walking approach is nonconfrontational—the patient and therapist are side by side, looking ahead rather than looking directly at one another; (2) the talking is being done in a less threatening setting; and (3) the patient is actively experiencing life rather than passively observing it in a chair.

Cancer. There is evidence that physical activity reduces the risk for cancer of the left side of the colon (38) and the breast (39).

COPD. Recent data (40) suggest that adding an exercise component to the rehabilitation program for patients who have COPD results in physiologic as well as psychological benefits, even for those with severe air flow obstruction.

A Plan for Therapy

To be maximally effective for therapy or health enhancement, the exercise prescription must fulfill certain basic requirements: It must be a daily activity (7 days a week), it must be fun, not painful or excessively fatiguing, and it must fit an individual's preferences (2,3). The selected activities must be readily available, not distant or difficult to reach, and preferably be close to the home or workplace. The clothes, equipment, and/or club membership associated with the activity must be inexpensive. Ideally, the activity should not depend on other people (team, class, or partners), but should permit group participation if desired. And finally, the activity must be suitable for lifelong participation.

The major form of the exercise must be aerobic (walking, running, cycling, swimming, or cross-country skiing). Variety is an important part of the prescription: At least two or preferably three different activities are recommended, for example walking-running-tennis or walking-cycling-swimming.

The choice of exercise should be guided by individual preference and previous experience. Walking and running are most often recommended because they do not require special training or skills. They are inexpensive, readily available, safe, and suitable for doing alone or with others. I use the acronym DF ALIVE to guide a patient's exercise prescription: Daily, Fun, Available, Lifelong, Independent, Variety, Endurance.

Encourage Lifelong Habits

The daily goal is to exercise for at least 30 to 60 minutes (2% to 4% of the day) and to make a conscious effort to do body movement throughout 16 hours of the day (ie, doing household chores, working, shopping, gardening, running errands, visiting, or socializing in an active manner) (2,3).

Each person should have an individualized lifelong exercise program designed to fit his or her lifelong situation and preferences.


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Dr Elrick was a lecturer on preventive medicine at Harvard Medical School in Boston and is now director of the Foundation for Optimal Health and Longevity in Bonita, California. He is a fellow of the American College of Physicians. Address correspondence to Harold Elrick, MD, The Foundation for Optimal Health and Longevity, 4095 Bonita Rd #207, Bonita, CA 91902.