Chapter
3
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Basic Physiology of
Cardiorespiratory Endurance Exercise
 Benefits of Cardiorespiratory Exercise
 Assessing Cardiorespiratory Fitness
 Developing a Cardiorespiratory Endurance Program
 Exercise Safety and Injury Prevention

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
Cardiorespiratory system: system
that circulates blood through the
body; consists of the heart, blood
vessels, and respiratory system
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
The heart
 Fist-sized muscle with four chambers
 Pulmonary circulation: circulatory
system that moves blood between
the heart and the lungs; controlled
by the right side of the heart
 Systemic circulation: circulatory
system that moves blood between the
heart and the rest of the body;
controlled by the left side of the heart
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
The heart
 Waste-laden, oxygen-poor blood
travels through venae cavae, into the
heart’s right upper changer, or atrium
 After the right atrium fills, it
contracts and pumps blood into the
heart’s right lower chamber, or ventricle
▪ Venae cavae: The large veins
through which blood is returned
to the right atrium of the heart
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
The heart
 Atrium: The right upper chamber
of the heart in which blood collects
before passing to the ventricles (pl atria)
 Ventricle: right lower chamber of heart
from which blood flows through arteries
to the lungs and other parts of the body
 Diffusion: process of oxygen moving
from lungs to the blood and carbon
dioxide moving from blood to the lungs
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
The heart
 Aorta: The body’s large artery;
receives blood from the left ventricle
and distributes it to the body
 Systole: Contraction of the heart
 Diastole: Relaxation of the heart
 Blood pressure: The force exerted
by the blood on the walls of the
blood vessels; created by the
pumping action of the heart
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
Blood vessels
 Blood vessels classified
by size and function
▪ Veins: Vessels that carry
blood to the heart
▪ Arteries: Vessels that carry
blood away from the heart
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
Blood vessels
 Endothelial cells: Cells
lining the blood vessels
 Nitric oxide: A gas released by the
endothelial cells to promote blood flow
 Capillaries: Very small blood vessels that
distribute blood to all parts of the body
 Coronary arteries: Pair of large blood
vessels that branch off aorta and supply
the heart muscle with oxygenated blood
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
The Respiratory System
 Respiratory system: The lungs, air
passages, and breathing muscles;
supplies oxygen to the body
and removes carbon dioxide
 Alveoli: Tiny air sacs in the lungs that
allow the exchange of oxygen and carbon
dioxide between the lungs and blood
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
The Cardiorespiratory System
at rest and during exercise
 At rest, your heart beats at a rate of
about 50 to 90 beats per minute, and you
take about 12 to 20 breaths per minute
▪ Stroke volume: amount of blood
the heart pumps with each beat
▪ Cardiac output: amount of blood
pumped by the heart each minute; a
function of heart rate and stroke volume
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

Metabolic rate: rate at
which body uses energy
Energy from food
 Carbohydrates, fats, and proteins
▪ Glucose: Simple sugar that circulates in blood
and is used by cells to fuel ATP production
▪ Glycogen: Complex carbohydrate stored in
the liver and skeletal muscles; the major fuel
source during most forms of intense exercise
▪ Glycogen is the storage form of glucose
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
ATP (adenosine triphosphate):
the energy “currency” of cells
 Adenosine triphosphate (ATP):
Energy source for cellular processes
 Cells store small amount of ATP
 When they need more, they create it
through chemical reactions using body’s
stored fuels—glucose, glycogen, and fat
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
Immediate
(“explosive”)
energy system:
Supplies energy
to muscle cells
through breakdown
of cellular stores of
ATP and CP
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
Nonoxidative (anaerobic)
energy system: Supplies energy
to muscle cells through breakdown
of muscle stores of glucose and
glycogen; also called the anaerobic
system or the lactic acid system
 Anaerobic: Occurring in
the absence of oxygen
 Lactic acid: Metabolic acid resulting from
the metabolism of glucose and glycogen
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
Oxidative (aerobic) energy system:
Supplies energy to cells through
breakdown of glucose, glycogen, and
fats; also called the aerobic system
 Aerobic: Dependent on
the presence of oxygen
 Mitochondria: Cell structures
that convert the energy in
food to a form the body can use
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
Maximal oxygen consumption
(VO2max): Highest rate of oxygen
consumption an individual is capable
of during maximum physical effort,
reflecting the body’s ability to
transport and use oxygen; measured
in milliliters of oxygen used per
minute per kilogram of body weight
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
The energy system in combination
 Intensity and duration of
exercise determines which
energy system predominates

Physical fitness and energy production
 Fitness program should target energy
system most important to your goals
 Cardiorespiratory system is
the key to overall fitness
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
Cardiorespiratory
endurance exercise
helps the body:
 Become
more efficient
 Cope better with
physical challenges
 Resist chronic diseases
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
Endurance exercises
enhance heart health:
 Maintaining or increasing the heart’s

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
blood and oxygen supply
Improving the heart muscle’s function
Strengthening the heart’s contraction
Increasing the heart’s cavity size
Increasing blood volume
Reducing blood pressure
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
Regular endurance exercise
improves metabolism
 Increases
capillaries in muscles
 Allows training
muscles to make the
most of oxygen and fuel
 Increases mitochondria
 Prevents glycogen depletion
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


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Cardiovascular Diseases
Cancer
Type 2 Diabetes
Osteoporosis
Inflammation
▪ Inflammation: body’s response to tissue and
cell damage, environmental poisons, or poor
metabolic health
 Deaths from all causes
▪ Physically fit people have
reduced risk of dying prematurely
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
Regular exercise increases
daily calorie expenditure
 Exercise increases resting metabolic rate

Improved immune function
 Immune system: The physiological
processes that protect us from diseases
such as colds, bacterial infections, and
even cancer
 Exercise increases immune function
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SOURCE: Wen, M, et al 2013 Physical activity and mortality
among middle-aged and older adults in the United States
Journal Physical Activity & Health Published online
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

Performing physical activities provides
proof of skill mastery and self-control
Endurance exercises lessen anxiety,
depression, stress, anger, and hostility,
while improving sleep
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
The 1-Mile Walk Test
 Estimates level of maximal oxygen
consumption based on time it takes to
complete one mile of brisk walking and
the heart rate at the end of the walk

The 3-Minute Step Test
 Measures how long it takes the
pulse to return to normal after
three minutes of stepping exercise
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
The 15-Mile Run-Walk Test
 Oxygen consumption increases with speed

The Beep Test
 A prerecorded series of tones sound off
at faster and faster intervals, and the
exerciser must keep up with the beeps

Monitoring Your Heart Rate
 Measure your heart rate using a heart
rate monitor or counting your pulse beats

Interpreting Your Score
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Set realistic goals
Set starting frequency,
intensity, and duration of
exercise at appropriate levels
Choose suitable activities
Warm up and cool down
Adjust program as fitness improves
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
Set “SMART” goals
 Specific
 Measurable
 Attainable
 Realistic
 Time frame-specific
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
Frequency of Training
 Experts recommend 3 to 5 days per week

Intensity of Training
 Target heart rate zone: Heart rates that
should be reached and maintained during
cardiorespiratory endurance exercise to
obtain training effects
▪ Heart rate reserve: Difference between
maximum heart rate and resting heart rate
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
Intensity of training
 MET: Unit of measure that represents
body’s resting metabolic rate
 Ratings of perceived exertion (RPE):
System of monitoring exercise intensity
based on assigning a number to the
subjective perception of target intensity
 Talk test
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
Time (duration) of training
 Total duration of 20 to 60
minutes per day recommended

Type of activity
 Cardiorespiratory endurance
exercises include activities that
involve rhythmic use of large muscle
groups for an extended period of time
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SOURCE: Pick, H L, ed 1978
Psychology from Research to
Practice Kluwer Academic/Plenum
Publishing Corporation With kind
permission of Springer Science and
Business Media and the author
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
Warm-up session should
include low-intensity, whole
body movements similar to those
in the activity that will follow
 Do not use stretching as part
of pre-exercise warm-up

Cooling down returns the
body to a non-exercising state
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
You must increase the intensity,
frequency, and duration of
exercise carefully to avoid
injury and overtraining
 Keep an exercise log or training diary

Maintaining cardiorespiratory fitness
 Cross-training: Alternating two
or more activities to improve
a single component of fitness
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
Hot weather and heat stress
 Dehydration: Excessive loss of body fluid
 Heat cramps: Sudden muscle
spasms and pain associated with
intense exercise in hot weather
 Heat exhaustion: Illness
resulting from exertion in hot weather
 Heatstroke: A severe and often fatal heat
illness characterized by significantly
elevated core body temperature
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SOURCE: Casa, D J, et al April–June 2000 National Athletic
Trainers’ Association position statement: Fluid replacement for
athletes Journal of Athletic Training 35(2): 212–224, 224a
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
Cold weather
 Hypothermia: Low body temperature
due to exposure to cold conditions
 Frostbite: Freezing of body
tissues characterized by pallor, numbness,
and a loss of cold sensation
▪ Wind chill: Measure of how cold it
feels based on the rate of heat loss from
exposed skin caused by cold and wind

Poor air quality
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
Consult a physician for the following:
 Head and eye injuries
 Possible ligament injuries
 Broken bones
 Internal disorders such as chest pain,
fainting, and heat intolerance
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
Managing minor exercise injuries
 For cuts and scrapes, stop the
bleeding and clean the wound
 For injuries to muscles
and joints, use RICE
▪
▪
▪
▪
Rest
Ice
Compression
Elevation
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
Preventing injuries
▪ Train regularly and stay in condition
▪ Gradually increase the intensity,
duration, or frequency of workouts
▪ Avoid or minimize
high-impact activities
▪ Get proper rest between
exercise sessions
▪ Drink plenty of fluids
▪ Warm up thoroughly before
you exercise and cool down afterward
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
Preventing injuries
▪ Achieve and maintain a normal
range of motion in your joints
▪ Use proper body mechanics
▪ Don’t exercise when
you are ill or overtrained
▪ Use proper equipment
▪ Don’t return to your normal exercise
program until athletic injuries have healed
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