What Are
the Specific Benefits of Exercise
By
Well-Connected
Longevity and
Aging Exercise, even after age 50, can add healthy and active years
to one's life. Studies continue to show that it is never too late to start
exercising and that even small improvements in physical fitness can
significantly lower the risk of death. Simply walking regularly can prolong
life in the elderly. Moderately fit people, even if they smoke or have high
blood pressure, have a lower mortality rate than the least fit. Resistance
training is important for the elderly, because it is the only form of exercise
that can slow and even reverse the decline in muscle mass, bone density, and
strength. Adding workouts that focus on speed and agility may be even more
protective for older people. Flexibility exercises help reduce the stiffness
and loss of balance that accompanies aging.
Cardiovascular
Health (Heart Disease and Stroke)
General Guidelines.
Inactivity is one of the
four major risk factors for heart disease, on par with smoking, unhealthy
cholesterol, and even high blood pressure. Like all muscles, the heart becomes
stronger and larger as a result of exercise so it can pump more blood through
the body with every beat. Exercise does not increase the maximum heart rate,
but a fit heart can pump more blood at this maximum level and can sustain it
longer with less strain. The resting heart rate of those who exercise is also
slower, because less effort is needed to pump blood. For preventing heart
disease frequency of exercises may be more important than duration. Exercise
even helps reverse some of the effects of smoking. Children should be
especially encouraged to exercise every day to prevent heart disease later in
life.
Effect on Coronary Artery Disease and Cholesterol
Levels. People who maintain an active lifestyle have a 45% lower risk
of developing coronary heart disease than do sedentary people. A recent study
reported that moderate dietary changes improve cholesterol levels and so lower
the risk for coronary artery disease only when an aerobic exercise program is
also followed. Regular aerobic exercises -- brisk walking, jogging, swimming,
biking, aerobic dance, and racquet sports -- are the best forms of exercise for
lowering LDL and raising HDL cholesterol levels. It may take up to a year of
sustained exercise for HDL levels to show significant improvement. Burning at
least 250 calories a day (the equivalent of about 45 minutes of brisk walking
or 25 minutes of jogging) seems to confer the greatest protection against
coronary artery disease. Even moderate exercise, however, reduces the risk of
heart attack, but in terms of raising HDL levels, more is better. Resistance
(weight) training offers a complementary benefit by reducing LDL levels.
Triglycerides, which rise after a high-fat meal, can be lowered either with a
single, prolonged (about 90 minutes) aerobic session or by several shorter
sessions during the day. One study indicates, however, that short-bursts of
exercise actually increase LDL oxidation -- the process that makes LDL
dangerous to the heart -- so individuals should always aim for a consistency in
their exercise program. Before engaging in any strenuous exercise, it is
advisable to consult a physician.
High Blood Pressure.
Studies indicate that regular exercise helps
keep arteries elastic, even in older people, which in turn keeps blood flowing
and blood pressure low. Sedentary people have a 35% greater risk of developing
hypertension than athletes do. No person with high blood pressure should start
an exercise program without consulting a physician. Studies have shown that
high-intensity exercise may not lower blood pressure as effectively as moderate
intensity exercise. In one study, for example, moderate exercise (jogging two
miles a day) controlled hypertension so well that more than half the patients
who had been taking drugs for high blood pressure were able to discontinue
their medication. Studies have indicated that T'ai Chi, an ancient Chinese
exercise involving slow, relaxing movements may lower blood pressure almost as
well as moderate-intensity aerobic exercises. Before exercising, people with
hypertension should avoid caffeinated beverages, which increase heart rate, the
workload of the heart, and blood pressure during physical activity.
Stroke. The benefits of exercise on stroke are uncertain. According to
one analysis, a group of 11,000 men, men who burned between 2,000 and 3,000
calories a week (about an hour of brisk walking five days a week) cut their
risk of stroke in half. Groups who burned between 1,000 and 2,000 calories or
more than 3,000 calories per week also gained some protection against stroke
but to a lesser degree. In the same study, exercise that involved recreation
was more protective than exercise routines consisting simply of walking or
climbing.
Heart Failure. Traditionally, heart failure
patients have been discouraged from exercising. Now, exercise is proving to be
helpful for many of these patients and, when performed under medical
supervision, does not pose a risk for a heart attack. In one study, patients
between the ages of 61 and 91 increased their oxygen consumption by 20% after
six months by engaging in supervised treadmill and stationary bicycle
exercises. Performing daily hand grip exercises may improve blood flow through
the arteries of patients with heart failure.
Diabetes
Diabetes, particularly type 2, is reaching epidemic proportions
throughout the world as more and more cultures adopt Western dietary habits.
Aerobic exercise is proving to have significant and particular benefits for
people with both type 1 and type 2 diabetes; it increases sensitivity to
insulin, lowers blood pressure, improves cholesterol levels, and decreases body
fat. Regular exercise, even of moderate intensity, improves insulin
sensitivity. In fact, studies of older people who engage in regular, moderate,
aerobic exercise (e.g., brisk walking, biking) lower their risk for diabetes
even if they don't lose weight. Anyone on insulin or who has complications from
diabetes must take special precautions before embarking on a workout program
(see, What Are the Hazards of Exercise?,
below).
Effects on Bones
and Joints
Osteoarthritis.
Exercise helps to reduce pain and stiffness, and increases flexibility, muscle
strength, endurance, and well being. Exercising also helps people reduce their
weight and maintain weight loss. Osteoarthritis patients should avoid
high-impact sports such as jogging, tennis, and racquetball. The three types of
exercise that are best for people with arthritis are range of motion,
strengthening (or resistance), and aerobic exercises. Strengthening exercises
include isometric exercises (pushing or pulling against static resistance) and
stretching exercises to build strength and flexibility without unduly stressing
the joints. These exercises may be particularly important if leg muscle
weakness turns out to be a cause of osteoarthritis, as some research suggests.
Low-impact aerobics also help stabilize and support the joints and may even
reduce inflammation in some joints. Cycling and walking are beneficial, and
swimming or exercising in water is highly recommended for people with
arthritis. One study compared a group of patients who embarked on an aerobic
and resistance exercise program with a group that received patient education;
the exercising group developed less disability and pain and showed a better
ability to perform physical tasks. Patients should strive for short but
frequent exercise sessions guided by physical therapists or certified
instructors.
Osteoporosis.
Exercise is very important for slowing the
progression of osteoporosis. Women should begin exercising before adolescence,
since bone mass increases during puberty and reaches its peak between ages 20
and 30. Weight bearing exercise, which applies tension to muscle and bone,
encourages the body to compensate for the added stress by increasing bone
density by as much as 2% to 8% a year. High-impact weight-bearing exercises,
such as step aerobics, are very protective for premenopausal women. These
exercises, however, increase the risk for osteoporotic fractures in elderly
patients, who would benefit most from regular, brisk, long walks. Even moderate
exercise (as little as an hour a week) helps reduce the risk for fracture, but
everyone who is in good health should aim for more. Careful weight training is
beneficial as well for older women. Low-impact exercises that improve balance
and strength, particularly yoga and T'ai Chi, have been found to decrease the
risk of falling; in one study, T'ai Chi reduced the risk by almost
half.
Back Problems.
One of the most common complaints of modern
men and women, lower-back pain, afflicts up to 80% of all Americans. Sedentary
living, obesity, poor posture, badly designed furniture, and stress all
contribute to back pain. An appropriate exercise program focusing on
flexibility and strengthening the muscles in the abdomen may help prevent back
problems. Yoga stretching is beneficial and can be incorporated into the
warm-up and cool-down periods. The best exercises for athletes with bad backs
include swimming, walking, and cross-country skiing. High-impact sports,
including aerobic dance and downhill skiing, should be avoided. Exercises that
strengthen the abdominal muscles such as partial sit-ups, which maintain the
back's normal curve and help support the body's weight, can alleviate stress on
the lower back. However, the classic full sit-up (raising your head and
shoulders off the floor up to your knees) may aggravate back pain and should be
avoided by anyone at risk for lower back problems.
Lung
Disease
Although exercise does not improve lung function, training
helps some patients with chronic lung disease by strengthening their limb
muscles, thus improving endurance and reducing
breathlessness.
Cancer
A number of studies have indicated that regular, even moderate,
exercise reduces the risk of colon cancer. Strenuous activity, in fact, adds
only slight or no additional benefit. Moderate exercise may also help reduce
the risk for prostate cancer and possibly for breast cancer. A recent study of
100,000 nurses, however, suggested that the benefits of exercise on breast
health may be greater or lesser at different times in a woman's life, depending
on her menstrual status and estrogen levels. For example, the study found no
added protection against from exercise in young adulthood (when the disease is
uncommon in any case).
Effects on Colds
and Flu
Although offering no evidence of improved immunity from
exercise, one study reported that people who exercised as little as once a week
in employee fitness programs averaged nearly five fewer sick days annually than
those who did not participate in such programs. The immediate effect of
exercise on the immune system is uncertain. High-intensity or endurance
exercises might actually suppress the immune system while they are performed.
Some highly trained athletes, for instance, report being susceptible to colds
after strenuous events. A recent study suggested that in people who already
have colds, exercise has no effect on the illness -- severity or duration of
the infection. People should avoid strenuous physical activity when they have
high fevers or widespread viral illnesses, however.
Central Nervous
System Diseases
People with multiple sclerosis, Parkinson's disease, and
Alzheimer's disease should be encouraged to exercise. Specialized exercise
programs that improve mobility are particularly valuable for Parkinson's
patients. Patients with neurological disorders who exercise experience less
spasticity as well as reduction in -- and even reversal of -- muscle atrophy.
In addition, the psychological benefits of exercise are extremely important in
managing these disorders. Exercise machines, aquatic exercises, and walking are
particularly useful.
Pregnancy
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. Experts advise, in
general, that when exercising, the expectant mother's pulse rate should not
exceed 70% to 75% of the maximum heart rate or more than 150 beats per minute.
Fit women who have exercised regularly before pregnancy, however, may work out
more intensively as long as no discomfort occurs. According to a new study,
vigorous exercise may improve the chances for a timely delivery. Overly
strenuous exercise during pregnancy is not advocated, however, for women
who did not exercise intensely before becoming pregnant. And all pregnant women
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. (No pregnant women should use hot tubs
or steam baths, which can cause fetal damage and miscarriage.) Swimming may be
the best option for most pregnant women. It involves no impact, overheating is
unlikely, and swimming face down promotes optimum blood flow to the uterus.
Walking is also highly beneficial. To strengthen pelvic muscles, women should
perform Kegel exercises at least 6 times a day, which involve contracting the
muscles around the vagina and urethra for 3 seconds 12 to 15 times in a
row.
Gastrointestinal
Problems
Older people who exercise moderately may have a lower risk for
severe gastrointestinal bleeding. Experts suggest that moderate exercise might
even reduce the risk for some intestinal disorders, including ulcers, irritable
bowel syndrome, indigestion, and diverticulosis.
Leg
Cramps
Exercise can even improve pain from clogged arteries in the
legs, a condition called intermittent claudication. The best approach in such
cases is to walk until pain develops; then rest until pain resolves before
resuming walking. In six-month studies, people had tripled the amount of time
they could walk before the onset of pain.
Weight
Loss
Exercise burns calories and can help individuals fight obesity.
If caloric intake remains constant, regular workouts lead to weight loss. Be
forewarned, however, that the pounds won't melt off magically. It takes 35
miles of walking or jogging to consume the calories in one pound of fat.
Effective weight loss means a long-term commitment to a regular program of
vigorous exercise. One recent study indicated that for obese patients, a few
daily sessions for as short as 10 minutes each was effective in helping the
patients adhere to an exercise program. Abdominal crunches may help replace
abdominal fat with muscle. To perform this exercise, the individual lies on the
back with the head and shoulders raised; he or she contracts the stomach
muscles, curling the torso slightly forward. Abdominal fat is a particular
danger to the heart, although it is unknown whether doing crunches will
specifically protect against heart disease. Swimming is less effective than
walking or cycling in reducing body fat, but overall regular aerobic exercise
is a good way to shed pounds. Contrary to popular belief, exercise does not
increase appetite in people who want to lose weight; oddly enough, however,
exercise improves appetite in people who are already lean. People should be
warned that without dieting, weight loss may be minimal with exercise alone,
because dense muscle mass replaces fat as the body gets more fit. Nonetheless,
a fit body will look more toned and be healthier.
Psychological and
Emotional Benefits
Aerobic exercise is linked with improved mental vigor,
including reaction time, acuity, and math skills. Exercising may even enhance
creativity and imagination. According to one study, older people who are
physically fit respond to mental challenges just as quickly as unfit young
adults. (Stretching and weight training appear to have no such effects.) Both
aerobic and nonaerobic workouts have been shown to reduce depression. According
to one study, exercise was as effective for improving mood in people with
clinical depression as some common forms of psychotherapy. Either brief periods
of intense training or prolonged aerobic workouts can raise levels of important
chemicals in the brain, such as endorphins, adrenaline, serotonin, and
dopamine, that produce feelings of pleasure, causing the so-called runner's
high. One study found that teenagers who were active in sports have a much
better sense of well being than their sedentary peers; the more vigorously they
exercised, the better was their emotional health. In one study, regular brisk
walking cut in half the incidence of sleep disturbances in people who suffer
from them. It should be noted that exercise in the evening, however, can
cause sleep disturbances. Rhythmic aerobic and yoga exercises may be
particularly helpful for combating stress, anxiety, and
sleeplessness.
Well-Connected
Board of Editors
Harvey Simon, M.D., Editor-in-Chief
Massachusetts Institute of Technology; Physician,
Massachusetts General Hospital
Masha J. Etkin,
M.D., Gynecology
Harvard Medical School;
Physician, Massachusetts General Hospital
John E. Godine,
M.D., Ph.D., Metabolism
Harvard Medical
School; Associate Physician, Massachusetts General Hospital
Daniel Heller,
M.D., Pediatrics
Harvard Medical School;
Associate Pediatrician, Massachusetts General Hospital; Active Staff,
Children's Hospital
Irene Kuter, M.D.,
D. Phil., Oncology
Harvard Medical School;
Assistant Physician, Massachusetts General Hospital
Paul C. Shellito,
M.D., Surgery
Harvard Medical School;
Associate Visiting Surgeon, Massachusetts General Hospital
Theodore A. Stern,
M.D., Psychiatry
Harvard Medical School;
Psychiatrist and Chief, Psychiatric Consultation Service, Massachusetts General
Hospital
Carol Peckham,
Editorial Director
Cynthia Chevins,
Publisher |
