1. Chapter 9: Circulatory Adaptations to Exercise
EXERCISE PHYSIOLOGY
Theory and Application to Fitness and Performance, 6th edition
Scott K. Powers & Edward T. Howley

2. Introduction
One major challenge to homeostasis posed by exercise is the increased muscular demand for oxygen
During heavy exercise, oxygen demands may  by 15 to 25 times
Two major adjustments of blood flow are;
 cardiac output
Redistribution of blood flow
A thorough understanding of the cardiovascular system is essential to exercise physiology

3. Objectives
Give an overview of the design and function of the circulatory system
Describe cardiac cycle & associated electrical activity recorded via electrocardiogram
Discuss the pattern of redistribution of blood flow during exercise
Outline the circulatory responses to various types of exercise

4. Objectives
Identify the factors that regulate local blood flow during exercise
List & discuss those factors responsible for regulation of stroke volume during exercise
Discuss the regulation of cardiac output during exercise

5. The Cardiovascular System
Purposes 1. 2. 3.

6. The Circulatory System
Heart
Pumps blood
Arteries and arterioles
Carry blood ________ from the heart
Capillaries
Exchange of __________ with tissues
Veins and venules
Carry blood __________ the heart

7. Structure of the Heart
Fig 9.1

8. Pulmonary and Systemic Circuits
________ side of the heart
Pumps _________ blood to the whole body via arteries
Returns ____________ blood to the right heart via veins
Pulmonary circuit
________ side of the heart
Pumps __________ blood to the ______ via pulmonary arteries
Returns ___________ blood to the ________ heart via pulmonary veins

9. The Myocardium
Fig 9.3

10. The Cardiac Cycle Systole ___________ phase Diastole _________ phase
Fig 9.5

11. Arterial Blood Pressure
Expressed as systolic/diastolic
Normal is 120/80 mmHg
High is 140/90 mmHg
Systolic pressure (top number)
Pressure generated during ________________ (systole)
Diastolic pressure
Pressure in the arteries during _____________ (diastole)

12. Blood Pressure ________________ ________________________ (MAP)
Difference between systolic and diastolic
________________________ (MAP)
Average pressure in the arteries
Pulse Pressure = Systolic - Diastolic
MAP = _______________________

13. Mean Arterial Pressure
Blood pressure of 120/80 mm Hg
MAP =

14. Measurement of Blood Pressure
Fig 9.7

15. Factors That Influence Arterial Blood Pressure
Fig 9.8

16. How is Blood Pressure Regulated?
Acute regulation
Achieved by _____________________
Long term regulation
Function of the ___________________
They do so by control of ____________________

17. Electrical Activity of the Heart
Contraction of the heart depends on electrical stimulation of the myocardium
Impulse is initiated in the __________ and spreads throughout entire heart
May be recorded on an __________________ (ECG)

18. Conduction System of the Heart
___________________
Fig 9.9

19. Q = _________ ________________
The amount of blood pumped by the heart each minute
Product of _________________
______ = number of beats per minute
______ = amount of blood ejected in each beat
Q = _________

20. Regulation of Heart Rate
2 prominent factors that influence HR
Decrease in HR
1. _____________________
Via ______________
Slows HR by inhibiting _________
Increase in HR
2. _____________________
Via cardiac ______________
Increases HR by stimulating ________

21. Regulation of Stroke Volume
SV at rest or during exercise is regulated by 3 variables
1. __________________ (EDV)
Volume of blood in the ventricles at the end of diastole (“preload”)
2. __________________
Pressure the heart must pump against to eject blood (“afterload”)
3. _________ of the ventricular contraction
“Contractility”

22. End-Diastolic Volume __________________ Affected by venous return:
Greater preload results in stretch of ventricles and in a more forceful contraction
Affected by venous return:
What factors regulate venous return? 1. 2. 3.

23. The Skeletal Muscle Pump
Rhythmic skeletal muscle contractions force blood in the extremities toward the heart
One-way valves in veins prevent backflow of blood
Fig 9.16

24. Average Aortic Pressure
Aortic pressure is ___________ related to stroke volume
High afterload results in a ___________ stroke volume
Requires greater force generation by the myocardium to eject blood into the aorta
Reducing aortic pressure results in _______ stroke volume

25. Ventricular Contractility
Increased contractility results in ________ stroke volume
Circulating epinephrine and norepinephrine
Direct sympathetic stimulation of heart

26. Factors that Regulate Cardiac Output
Parasympathetic
nerves
Mean arterial
pressure
Cardiac = Cardiac Rate x Stroke Volume
Output
Contraction
strength
EDV
Sympathetic
nerves
Stretch
Frank-
Starling
Fig 9.18

27. Hemodynamics
The study of the physical principles of blood flow

28. Physical Characteristics of Blood
___________
Liquid portion of blood
Contains ions, proteins, hormones
Cells
Contain hemoglobin to carry oxygen
Important in blood clotting

29. Percent of blood composed of cells
____________
Percent of blood composed of cells
Fig 9.19

30. Hemodynamics Based on interrelationships between: ___________
Since large increases in P are hazardous to health – decreasing resistance is the primary factor used to achieve increases in BF during exercise with a small rise in P

31. Hemodynamics: Pressure
Blood flows from ___  ___ pressure
Proportional to the difference between MAP and right atrial pressure (P)
BF depends on P at 2 ends of vascular system
P at 2 ends of a vessel are equal = __________

32. Blood Flow Through the Systemic Circuit
Fig 9.20

33. Hemodynamics: Resistance
What factors contribute to the resistance of blood flow? 1. 2. 3.
A _________ change in vessel diameter can have a dramatic impact on resistance!
Resistance is directly proportional to these 2 factors
Most important factor determining vascular resistance
Resistance =

34. Hemodynamics: Blood Flow
___________ proportional to the pressure difference between the two ends of the system
___________ proportional to resistance
Flow =

35. Sources of Vascular Resistance
MAP __________ throughout the systemic circulation
Largest drop occurs across the _____________
Arterioles are called “resistance vessels”

36. Pressure Changes Across the Systemic Circulation
Fig 9.21

37. Oxygen Delivery During Exercise
Oxygen demand by muscles during exercise is many times greater than at rest
Increased O2 delivery accomplished via 2 mechanisms: 1. 2.

38. Changes in Cardiac Output
Cardiac output increases due to:
Increased ____
Linear increase to max
Plateau at ~40% VO2max
Oxygen uptake by the muscle also ______
Higher arteriovenous difference
Max HR = Age (years)

39. Changes in Cardiovascular Variables During Exercise
Fig 9.22

40. Redistribution of Blood Flow
Muscle blood flow to working skeletal muscle
Splanchnic blood flow  to less active organs
Liver, kidneys, GI tract

41. Changes in Muscle and Splanchnic Blood Flow During Exercise
Fig 9.23

42. Increased Blood Flow to Skeletal Muscle During Exercise
What regulates blood flow to various organs during exercise? 1. 2.
Blood flow increased to meet metabolic demands of tissue
This happens because of muscle vasodilation
O2 tension, CO2 tension, pH, nitric oxide

43. Redistribution of Blood Flow During Exercise
Fig 9.24

44. Circulatory Responses to Exercise
Heart rate and blood pressure
Depend on:
Type, intensity, and duration of exercise
Environmental condition
Emotional influence

45. Transition From Rest  Exercise and Exercise  Recovery
Rapid increase in HR, SV, cardiac output
Plateau in submaximal (below lactate threshold) exercise
Recovery depends on:
Duration and intensity of exercise
Training state of subject

46. Incremental Exercise Heart rate and cardiac output Stroke volume
Increases linearly with increasing work rate
Reaches plateau at 100% VO2max
Stroke volume
Systolic blood pressure
Increases with increasing work rate
Double product – also called___________
Increases linearly with exercise intensity
Indicates the work of the heart
Double product =

47. Arm vs. Leg Exercise
At the same oxygen uptake arm work results in higher:
_______
Due to higher ______________ stimulation
Due to _____________ of large inactive muscle mass .

48. Heart Rate and Blood Pressure During Arm and Leg Exercise
If these 2 factors increase so will _________________________
Fig 9.26

49. Prolonged Exercise Cardiac output is maintained Cardiovascular drift
Gradual decrease in _________
Gradual increase in _________
Cardiovascular drift
What is the drift due to? 1. 2. .

50. HR, SV, and Q During Prolonged Exercise
Fig 9.27

51. Cardiovascular Adjustments to Exercise
Fig 9.23