Chapter 13
Nutrition and Physical
Activity
Exercise, Health and Fitness
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Fitness is defined as the ability to perform routine
physical activity without undue fatigue.
The overload principle assumes that the body will
adapt to the stresses placed on it.
Aerobic exercise includes endurance exercises such
as jogging, swimming or cycling, or any exercise that
increases heart rate and requires oxygen in
metabolism.
The cardiorespiratory system includes the circulatory
and respiratory systems, delivering oxygen and
nutrients to the cells.
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Exercise, the Heart and the Muscles
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Regular aerobic exercise strengthens the heart muscle, increases
stroke volume and decreases the resting heart rate.
The resting heart rate can be measured by counting the number of
pulses per minute while at rest.
Aerobic capacity is the body’s maximum ability to generate ATP
by aerobic metabolism during exercise. Aerobic capacity is also
called VO2 max.
Stress or overload during exercise causes muscles to adapt by
increasing in size and strength. This is called hypertrophy.
When muscles are not used, they atrophy, becoming smaller and
weaker.
Exercise builds and maintains muscles. People who are fit have a
greater proportion of lean body tissue than those who are not fit.
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Health Benefits of Exercise
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In addition to increased flexibility and the
ability to easily perform daily activities,
benefits of regular exercise include:
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Weight management
Cardiovascular health
Diabetes prevention or management
Bone and joint health
Possible reduction of cancer risk
Psychological health
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Exercise Recommendations
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Target Heart
Rates During
Aerobic
Exercise
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Components of a Good Exercise
Regimen
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Suggestions for Starting and Maintaining
an Exercise Program
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Fueling Exercise
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Aerobic metabolism is metabolism in the presence of
oxygen. Glucose, fatty acids and amino acids are
completely broken down to form CO2 and H20 and to
produce ATP.
Anaerobic metabolism is metabolism in the absence
of oxygen. Each molecule of glucose produces two
molecules of ATP. Glucose is metabolized in this way
when oxygen cannot be supplied quickly enough to the
tissues to support aerobic metabolism.
Anaerobic metabolism is also called anaerobic
glycolysis.
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Fueling Exercise by the Minute
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The Process of Anaerobic Metabolism
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The Effect of Exercise Intensity
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Nutrient Needs for Physical Activity
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Relationship of Exercise to Intake
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The source of dietary energy can be as important
as the amount of energy in an athlete’s diet.
Vitamins and minerals requiring special attention
from athletes:
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B vitamins
Antioxidant vitamins, such as vitamins C and E
Iron
Calcium
The general proportion of energy for athletes and
healthy individuals should be:
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45-65% total energy from carbohydrates
20-35% from fat
10-35% from protein
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Fluid Needs for Physical Activity
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During exercise, water is needed to eliminate heat, to
transport oxygen and nutrients to the muscles and to remove
waste products such as lactic acid from the muscles.
The ability to dissipate heat depends on hydration levels.
At rest in a temperate climate, an adult loses about 4½ cups
of water per day through evaporation from the skin and
lungs.
Even with regular consumption, it may not be possible to
consume sufficient fluid to remain properly hydrated.
Failure to compensate for fluid losses can result in
dehydration.
If heat cannot be lost from the body, body temperature rises
and exercise performance as well as health can be
jeopardized.
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Fluid Needs for Physical Activity
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Dehydration occurs when water loss is great enough for
blood volume to decrease.
Dehydration reduces the body’s ability to deliver oxygen
and nutrients to muscles.
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Hyponatremia
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Heat-Related Illnesses
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Recommended Fluid Intake
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Food and Beverages to Maximize
Performance
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What Are You
Getting From
That Sports
Bar?
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Impact of Diet versus Supplements
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Chapter 13
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