Chapter 9
Health Benefits of
Physical Activity
Our unhealthy lifestyle
• We participate in work and leisure
activities that are far less active than in
the past.
• We produce and eat more food than we
should.
• We control our environment with very
little expenditure of physical energy.
• We subject ourselves to more and
unusual stressors.
What the Surgeon General says
1. People of all ages, both male and female,
benefit from regular physical activity.
2. Significant health benefits can be obtained by
including a moderate amount of physical
activity on most days of the week.
3. Additional health benefits can be gained
through greater amounts of physical activity.
4. Physical activity reduces the risk of
premature death and certain diseases, and
promotes mental health.
What the Surgeon General says (cont.)
5. More than 60 percent of American adults do
not regularly exercise, and 25 percent are not
active at all.
6. Nearly half of American youth 12-21 years of
age are not vigorously active on a regular
basis, and activity declines during
adolescence.
7. Daily enrollment in physical education classes
declined among high school students from 42
percent in 1991 to 25 percent in 1995.
8. Interventions to promote physical activity in
schools, work sites, and health care settings
are being evaluated.
Fitness and mortality
• The more active you are, the less likely
you are to die prematurely.
• A modest increase in physical activity
can have a substantial benefit.
• The reduction in risk of overall mortality
from improving cardiorespiratory fitness
from low to moderately fit is
approximately the same as stopping
smoking.
The relationship between physical activity
and cardiorespiratory fitness versus allcause mortality is inverse.
Fitness and cardiovascular disease
• Physical activity decreases the risk of
developing cardiovascular diseases
– Coronary heart disease
– Stroke
– Hypertension
– Peripheral vascular disease
The relationship between physical activity and
the cardiovascular diseases (coronary heart
disease, stroke, hypertension, and peripheral
vascular disease) is inverse.
Elevated levels of certain blood lipids (total
cholesterol, chylomicrons, VLDL, LDL, IDL,
lipoprotein a, and triglycerides) are positively
related to the risk of coronary heart disease.
High levels of high-density lipoproteins
(HDL) protect against the development of
coronary heart disease.
Body weight and health
• Relationship between body weight and
mortality is disease specific.
• Low body weight is beneficial with respect
to coronary heart disease and diabetes
mellitus.
• For hypertension and kidney disease,
death is associated with both low and high
body weight.
• For pneumonia, influenza and suicide,
death is more likely at low body weight.
Ratio of actual to
predicted mortality
versus body mass
index (BMI) for
causes of death
Fat cells and obesity
• Hypertrophic obesity—normal number of fat cells,
which are twice as large as those of a non-obese
person
• Hyperplastic obesity—higher number of enlarged fat
cells
• Number of fat cells in the human body is established
during
– Latter part of gestation
– First year of infancy
– Adolescent growth spurt
• Once established, the number of fat cells usually
remains constant despite weight gain or loss
• The size of fat cells change with weight gain or loss
Exercise and weight loss work together
• Calories are expended during physical activity.
• Additional calories are expended after exercise.
• Physical activity helps to maintain the basal
metabolic rate (BMR), whereas caloric restriction
alone usually results in a decrease in BMR.
• Moderate exercise does not increase and may
decrease appetite.
• Spot reducing does not work.
Visit Physical Activity and Weight Control at
www.niddk.nih.gov/health/nutrit/pubs/physact.htm and the
American Obesity Association Homepage at www.obesity.org
A good weight loss program,
according to the ACSM
• Provides a caloric intake not lower than 1,200
kilocalories a day for adults
• Includes food acceptable to the dieter
• Provides a negative caloric balance resulting
in gradual weight loss
• Includes the use of behavior modification
• Includes an endurance exercise program
• Provides that the new eating and physical
activity habits can be maintained for life
Exercise and cancer
• The level of physical activity is inversely
related to the risk of developing colon
cancer.
• Activity patterns during adolescence and
early adulthood may influence the risk of
developing cancers of the uterus, ovaries,
cervix, vagina, and breasts.
• No studies provide evidence of a direct
cause-and-effect relationship between
physical activity and prevention of cancer.
The relationship between physical
activity and the risk of developing
colon cancer is inverse.
How exercise can help
individuals with diabetes
• Exercise can help type 1 diabetics improve
control of blood glucose levels by increasing
insulin sensitivity.
• For type 2 diabetics, regular exercise
improves insulin sensitivity and glucose
tolerance.
How physical activity may reduce
the risk of osteoporosis
• During adolescence:
– By aiding the development of bone mass and
density
• During middle age:
– By helping to maintain bone mass and density
• In post-menopausal women:
– By supplementing the effect of estrogen
therapy if prescribed on the retention and
development of bone density
Visit the National Osteoporosis Foundation at www.nof.org
Factors to consider when developing an
exercise program for post-menopausal women
• The wrong type of exercise can do more harm
than good.
• Weight training can improve bone density
while increasing muscular strength and
balance.
• Adequate calcium intake is essential.
• Exercise is not a substitute for estrogen
replacement therapy if prescribed.
Visit Physical Activity and Health, Women at
www.cdc.gov/nccdphp/sgr/women.htm
Some effects of physical activity
on mental health
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More positive outlook
Greater self-esteem
Enhanced ability to respond to stressors
Reduced symptoms of depression
Positive effects on trait and state anxiety
High fit individuals are less likely than low
fit individuals to suffer from anxiety or
depression.