Chapter 17
Functional Capacity of the
Cardiovascular System
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Cardiac Output
• Cardiac output (Q) = HR × SV
• Methods of Measuring Q
– Direct Fick
– Indicator dilution
– CO2 rebreathing
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Direct Fick Method
Q = V O2 mL · min−1
a-v O2 difference
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Indicator Dilution Method
Q=
Quantity of dye injected
Average dye
concentration blood
for duration of curve
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×
Duration of curve
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
CO2 Rebreathing Method
Q=
 CO
V
2
× 100
v-aCO2 difference
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Cardiac Output at Rest
• Values vary depending upon emotional
state.
• Average male ~5 L · min-1
• Average female ~4 L · min-1
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Untrained Characteristics of Q
• HR ~ 70 BPM
• SV ~ 71.4 mL
• Average women ~25% lower due to smaller
size
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Endurance Athletes
• Characteristics of Q
– HR ~ 50 BPM
– SV ~ 100 mL
• Mechanisms
– Increased vagal tone w/decreased sympathetic
drive
– Increased blood volume
– Increased myocardial contractility and
compliance of left ventricle
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Cardiac Output During Exercise
• Q increases rapidly during transition from
rest to exercise.
• Q at max exercise increases up to 4 times.
Q
Untrained 22 L
Trained
35 L
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HR
195
195
SV
113 mL
179 mL
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Stroke Volume: Diastolic Filling vs.
Systole Emptying
• Mechanisms for increased SV with
training
– Increased blood volume – increase diastolic
filling
– Increased preload – Starling’s Law of the
Heart
– Increased Contractility – greater systolic
emptying
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Cardiovascular Drift
• Results from
– Dehydration
– Reduction in SV
• HR drifts upward to maintain same Q
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Cardiac Output Distribution
• Blood flows to tissues in proportion to
their metabolic activity.
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Cardiac Output and Oxygen
Transport
Rest
Q = 5 L · min-1
O2 transport = 1,000 mL – 200 mL/L blood
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Exercise
• Max Q averages ~ 16 L · min-1
• O2 transport = 200 mL/L blood
• Result
– 3200 mL O2
• Training enables Q to increase up to
40 L · min-1, increasing O2 transport
up to 8,000 mL.
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Close Association Between
Max Q and V O2max
• An almost proportionate increase in max Q
accompanies increases in V O2max with training.
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Cardiac Output Differences:
Men, Women, and Children
• Women have a 10% lower hemoglobin level than
men.
• Result is a 5 – 10% increase in Q at any submax
level of O2 consumption
• Children have higher HR
– Result is smaller Q, expanded a-vO2
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
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O2 Extraction: The a- v O2 Difference
• O2 consumption increases during exercise.
– Increases Q
 O by tissues
– Increases extraction of V
2
• V O2 = Q x a- v O2 difference
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
a- vO2 Difference during Rest
• 20 mL O2 · dL-1 arterial blood
• 15 mL O2 · dL-1 venous blood
• 5 mL a- vO2diff
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
a-v O2 Difference during Exercise
• 20 mL O2 · dL-1 arterial blood
• 5 – 15 mL O2 · dL-1 venous blood
• Up to a threefold increase in O2 extraction
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Severe Heart Disease
• Exhibit low ability to improve Q or SV
• Skeletal muscle adaptations allow for
increased O2 extraction.
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Factors Affecting the a- v O2
Differences
• Redistribution of flow to active tissues during
exercise
• Increased capillary density due to training increases
surface area and O2 extraction
• Increased number and size of mitochondria
• Increased oxidative enzymes
• Vascular and metabolic improvements
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Cardiovascular Adjustments to
Upper-Body Exercise
• Max O2 consumption
– Upper-body exercise results in max O2
consumption ~20 – 30% lower than
lower-body exercise.
• Higher O2 consumption for a given submax
workload
– Lower mechanical efficiency
– Muscular effort to stabilize torso
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Physiologic Response
• Submaximal arm exercise produces
> HR
> Pulmonary ventilations
> RPE
> BP response
than comparable leg exercise
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McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition
Physiologic Response
• Exercise prescription for arm exercise
should not be based on values obtained
from lower-body exercises.
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy,
Nutrition, and Human Performance, Sixth Edition