Chapter 6
Impaired Aerobic
Capacity/Endurance
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Physiology of Aerobic Capacity and
Endurance
 Physical Activity
 Exercise
 Physical Fitness
Cardiorespiratory
Endurance
The ability of the whole
body to sustain
prolonged exercise.
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Energy Sources Used During
Aerobic Exercise
Fat, Carbohydrates, Protein
ATP
ATP
ATP
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Metabolic Pathways
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Fuel Source Selection During Exercise
CHO is the preferred fuel
source for ATP to supply
the body with energy
during exercise.
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Normal and Abnormal Response to
Acute Aerobic Exercise
Heart Rate – Linear relationship between HR and
intensity of exercise (factors – age, fitness level,
type of activity, disease, medications, bl volume,
environment).
Stroke Volume – Workload and SV increase
linearly until 50% aerobic capacity (factors –
body composition and exercise intensity).
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Cardiac Output
• Cardiac output and workload increase
linearly b/c of increases in HR and SV
(factors – age, posture, body size,
disease, physical conditioning).
• Arterial/venous oxygen difference – As
exercise increases a-VO2 diff increases
linearly.
• Blood flow – at rest 15–20%
muscle.
During exercise 80–85%
muscle.
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• Blood pressure – Systolic BP linearly with work
load. Diastolic BP changes very little.
• Pulmonary ventilation – During exercise,
breathing increases to facilitate amount of air
exchanged per minute. Tidal volume and
respiratory rate increase in proportion to
exercise.
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Physiologic and Psychological Adaptations
to Cardiorespiratory Endurance Training
•
•
•
•
•
•
•
•
Increased
Heart wt, vol
Left ventricle size
SV, cardiac output
Hemoglobin
Peripheral capillary
formation
Respiratory rate
PV during max exercise
Vo2, Vo2 different during
maximal exercise
•
•
•
•
•
Decreased
Resting and submax HRs
Time required to return to
resting levels
Systolic/diastolic pressure
Resting and submaximal
respiratory rates
Body fat
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Psychologic Benefits of Training
Improved
Moods
Depression
Anxiety
Psychological well-being
Perceived quality of life
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Causes of Impaired Aerobic
Capacity/Rehabilitation Indications
Heart Muscle
Coronary artery
disease
Pericarditis
Congestive heart
failure
Aneurysms
Heart Valves
Rheumatic fever
Endocarditis
Mitral valve prolapse
Congenital deformities
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Nervous System
Arrythmias
e.g., tachycardia,
bradycardia
Peripheral Vascular
Disease
Arterial disorders,
venous disorders,
lymphatic disorders
e.g., atherosclerosis,
embolism, Buerger’s
disease, Raynaud’s,
deep vein thrombosis,
lymphedema, venous
stasis
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Examination/Evaluation of
Aerobic Capacity
Examination and
evaluation of CV and
respiratory systems
should be included in
exam of all clients
Tests Identify
Presence of disease
Establishing a
baseline aerobic
capacity
Measuring change in
aerobic capacity
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Patient/Client History
General demographic information
Social/health habits
General health status (physical, role, social
functioning, etc.)
Clinical tests (blood cholesterol)
Medications
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Systems Review
Examination of other
major body systems
Skin integrity
Muscle strength
Joint ROM
Balance
Gait function
Ability to make needs
known
Communication
Affect
Cognition
Language
Learning style
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Screening Examination
Pain in chest, neck,
jaws, or areas of
ischemia
Shortness of breath at
rest or with mild
exertion
Dizziness or syncope
Orthopnea
Ankle edema
Palpitations or
tachycardia
Intermittent
claudication
Known heart murmur
Unusual fatigue or
shortness of breath
with usual activities
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Tests and Measures
Maximal Graded Exercise Tests
Graded or variable workload over 8-12 min.
Commonly done in conjunction with ECG.
Submaximal Graded Exercise Tests
Estimates VO2max. Includes bicycle ergometer
tests (Astrand-Ryhming, YMCA protocol),
treadmill tests, step tests, field tests.
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Anthropometric Characteristics
Hydrostatic – gold standard
(requires expensive
specialized equipment and patient tolerance)
BMI (body mass index)
Bioelectric impedance
Near-infrared interactance
Skinfold measurements
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Circulation
Blood pressure
Heart rate, rhythm,
and pattern
Respiratory rate,
rhythm, and pattern
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Therapeutic Exercise Intervention
Objective of exercise prescription is to assist in
the adoption of regular physical activity as a
lifestyle habit.
Consider – behavioral characteristics, personal
goals, exercise preferences of the individual.
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Mode of Intervention
Walking
Jogging
Cross-country skiing
Bicycling
Rope jumping
Rowing
Swimming (or water
aerobics)
Aerobic dance
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Dosage – Training Type
 Continuous – (e.g., 30
minutes using 1 or 2
exercises)
 Interval Training – Multiple
bouts of higher intensity w/
short periods of rest/light
activity (e.g., 2 minutes)
 Circuit Training - Individual
rotates through series of
exercise stations.
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Dosage – Training Sequence
1.
2.
3.
4.
Initial warm up (5–10
minutes) of large
muscle groups
(walking, cycling, etc.)
Stretching exercises
More vigorous
cardiovascular
exercises as prescribed
Cool down with
stretching
1&4
2&4
3
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Dosage – Frequency
Determined considering patient’s goals
Optimal frequency – 3–5 times per week
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Dosage – Intensity
Based on overload principle and within the
patient’s functional limitations
Select a training range to allow for flexibility
(e.g., 60–70% of HR max)
60–80% has been the general recommendation
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Dosage – Duration
Depends on goals, frequency, intensity &
conditioning level of patient
Optimal duration is 20–30 minutes per
session
If unable, several 10-minute sessions can
be performed until tolerance increases
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Precautions and Contraindications
Refer to systems review and physiologic
causes of impairment
Consider any injury or disease affecting
systems (e.g., patients with DJD could
participate in non-weight-bearing
exercises)
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Supervision During Exercise
Initial screening and
medical evaluation
are important to
determine if the
individual requires
supervision.
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Patient-Related Instruction/Education
Patient education (PE) should include “why” &
“how” of warm up, training, and cool down
phases.
PE on negative signs and symptoms
necessitating cease of activity.
PE should include maintenance program upon
discharge and importance relating to longterm health maintenance.
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Life Span Guidelines
Children exercising in hot environments should
do so at lower intensity.
Age 6 up to & including adults – moderate
intensity, 30 minutes, 5–7 days/wk.
Elderly individuals – 30 minutes, 5–7 days/wk
with emphasis on minimizing impact on joints
(e.g., water exercising, cycling).
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Summary
 Aerobic capacity or
VO2max is the highest
rate of oxygen the body
can consume during
maximal exercise.
 CHOs are the preferred
energy source for the
body during exercise.
 During acute exercise,
HR, SV, Q, a-vO2 diff, BP,
and RR increase
proportionally to the
exercise workload.
 Benefits of CV endurance
training include +ve
changes in CV & resp.
systems that provide
protection from disease &
improved psych. wellbeing and quality of life.
 Impaired aerobic capacity
can occur – result of
primary CV & pulm.
disease, diseases of
other systems that limit
mobility, prolonged bed
rest, aging, and
sedentary lifestyle.
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Summary (cont.)
 Areas of PT history requiring
attention are: risk factors for
CV disease, social/health
habits such as smoking and
physical activity, functional
ability, and medication history.
 Tests and measures include:
graded exercise tests, body
composition, tests/measures of
circulation (e.g., blood
pressure).
 Exercise prescription should
be based on the results of an
appropriate exercise test b/f
the initiation of a CV program.
 CV endurance training can be
performed using a variety of
exercise modes and training
techniques.
 Exercise prescription should
be based on the individual’s
needs and interests, and
comorbidities that affect
activity performance should be
considered.
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Summary (cont.)
 CV endurance training is
part of a well-balanced
exercise program
including muscle
strengthening,
endurance, and flexibility
exercises.
 Clinician should be able
to identify signs and
symptoms, intolerance,
and contraindications for
graded testing.
 Supervision requirements
are based on patient’s
history, risk factors, and
abilities.
 Educating the patient
regarding the specifics of
the program(s) will
increase the likelihood of
patient compliance and
adoption of CV exercise
as a lifelong habit.
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