Exercise's Effects on Other Conditions:

Physical activity makes you healthier. It lowers your risk for cardiovascular disease and reduces bone loss. Physical activity also helps the body use calories more efficiently, which helps you eliminate body fat and lose weight. It also helps you maintain weight loss by increasing your metabolism and reducing your appetite.

Effect of Exercise on Cancer

A number of studies have indicated that regular exercise may reduce the risk of breast, colon, and possibly prostate cancers.

Studies confirm that exercise significantly reduces the risk of both colon cancer (by up to 50%). Exercise also decreases the risk of breast cancer in pre and post menopausal women by up to 30%.

Low intensity exercise has a protective effect against colon cancer, according to studies, including the Nurses Health Study and the American Cancer Society's Cancer Prevention Study II. People with colon cancer who exercise may reduce their risk of a recurrence.

Exercise also has a beneficial effect on people receiving treatment for cancer. Aerobic and resistance training can reduce fatigue in patients undergoing chemotherapy or radiation treatments for cancer. Fatigue is a common side effect of such treatments.

Effects on the Gastrointestinal Tract

Endurance athletes often report stomach problems, such as bloating, diarrhea, and gas, even at rest. Moderate regular exercise might reduce the risk for some intestinal disorders. These disorders include ulcers, irritable bowel syndrome, indigestion, and diverticulosis. Older people who exercise moderately may have a lower risk for severe gastrointestinal bleeding.

Effects on Neurological Diseases and Mental Decline

Studies have shown that regular exercise, particularly walking, helps reduce one's risk for memory loss. Epidemiologic studies have found an association between increased exercise and slower rate of functional decline in older adults. To date, there are no clear explanations for this apparent benefit. Aerobic exercise has been linked to improved reaction time in people of all ages.

Exercise seems to improve the physical and emotional well-being of patients who already have Alzheimer's disease. The patients exercised moderately for as little as 60 minutes each week. Doctors noted patients who exercised were less depressed, wandered away less, suffered fewer falls, and were placed in nursing homes later, compared to patients who did not exercise.

People with existing neurological diseases, such as multiple sclerosis, Parkinson's disease, and Alzheimer's disease, should be encouraged to exercise. Specialized exercise programs that improve mobility are particularly valuable for patients with Parkinson's disease. Patients with neurological disorders who exercise experience less stiffness, as well as reduction in, and even reversal of, muscle wasting. In addition, the psychological benefits of exercise are extremely important in managing these disorders. Exercise machines, aquatic exercises, and walking are particularly useful.

Effects on Emotional Disorders

Some research has suggested that exercise may have antidepressant effects. Although there is little evidence that exercise can correct major depression, a number of studies have suggested benefits in mild to moderate depression in adults. Research findings include:

• Just 30 minutes of brisk exercise three times a week was as effective as medication in relieving symptoms, and reducing relapse, in many patients with mild-to-moderate depression.
• Over half of older women with depression that did not respond to medication showed improvement with 10 weeks of exercise. (About a third of women who did not exercise also improved during that time.)
• Studies on elderly, depressed patients report modest benefits from exercise, even in those who do not respond to antidepressants. Simply participating in a group activity may help improve mood.
• Teenagers who are active in sports have a greater sense of well-being than their sedentary peers. The more vigorously they exercise, the better their emotional health.
• Physical inactivity is strongly linked to depression in children 8 - 12 years of age.
• Exercise decreases some of the most troublesome emotional symptoms of menopause. Women who exercise during menopause showed less anxiety, stress, and depression than inactive women with menopause did.

Specific exercises may be particularly beneficial:

Aerobics. Either brief periods of intense training or prolonged aerobic workouts can raise levels of certain chemicals in the brain. These chemicals -- which include endorphins, adrenaline, serotonin, and dopamine -- produce the so-called runner's high. Weight loss and increased muscle tone can boost self-esteem.

Yoga. Yoga practice, which involves rhythmic stretching movements and breathing, has been found to positively affect mood. It may have clinical potential as a technique for improving and stabilizing mood. A study comparing yoga to aerobic exercise found that men have significantly lower levels of tension, fatigue, and anger after yoga, compared with levels after swimming. Yoga and swimming tended to produce equal benefits in women.

Effect of Exercise on Pregnancy

Moderate exercise in healthy pregnant women does not increase the risk for miscarriage, preterm labor, or rupture of the membrane. Not exercising increases the risk for complications, including low-birth weight babies. Exercising increases the fetal heart rate, which in turn protects the baby.

Healthy women with normal pregnancies should exercise at least three times a week, being careful to warm up, cool down, and drink plenty of liquids. Many prenatal calisthenics programs are available.

The following are specific exercises that may benefit the pregnant woman:

• Swimming and water aerobics may be the best option for most pregnant women. Water exercises involve no impact, overheating is unlikely, and swimming face down promotes optimum blood flow to the uterus.
• Performing yoga exercises under the guidance of informed instructors can be very helpful.
• Walking is also beneficial.

To strengthen pelvic muscles, women should perform Kegel exercises at least six times a day. This involves contracting the muscles around the vagina and urethra for three seconds 12 - 15 times in a row.

The following precautions are generally recommended for pregnant women who exercise:

• Fit women who have exercised regularly before pregnancy may work out intensely as long as the doctor approves and no discomfort occurs. However, excessive exercise can cause undernourishment of the fetus.
• As a rule for previously sedentary, low-risk expectant mothers, the pulse rate should not exceed 70 - 75% of the maximum heart rate, or more than 150 beats per minute. Any sedentary expectant mother should check with her doctor before starting an exercise program.
• Vigorous exercise may improve the chances for a timely delivery. All pregnant women, however, should avoid high-impact, jerky, and jarring exercises, such as aerobic dancing, which can weaken the pelvic floor muscles that support the uterus.
• During exercise, women should monitor their temperature to avoid overheating, a side effect that can damage the fetus. (Pregnant women should also not use hot tubs or steam baths, which can cause fetal damage and miscarriage.)

Note: Strenuous exercise may affect the flavor of breast milk for a short time afterward. Nursing mothers who engage in such activity might want to wait about an hour after exercising before they feed their infant.