7. The Athletic Heart

Question 1

What is the HR’s response to dynamic exercise?

Answer 1

Roughly a tripling of HR

Question 2

How does training affect SV and HR?

Answer 2

• Increased SV
• Lower resting HR

Question 3

What is SV’s response to dynamic exercise? How?

Answer 3

• Increased filling due to:
  
  • Venous return
  • Preload
• Increased emptying due to:
  
  • Frank Starling Law
  • Increased contractility

Question 4

How does peripheral resistance respond to the tissues’ increased demand for O₂?

Answer 4

Decreased peripheral resistance to flow

Question 5

How is blood flow to the organs redistributed w/ increasing exercise intensity?

Answer 5

• Brain always gets constant amount
• Flow to the heart and muscles increases proportional to exercise intensity
• Flow to the kidneys, liver, stomach, intestines, etc. decrease as exercise intensity increases

Question 6

Arterial and venous pO₂ at rest vs. during exercise

Answer 6

At rest:

• Less O₂​ extraction from blood
• More oxygenated blood goes to veins

During exercise:

• Increase in O₂ extraction from blood
• For same amount of O₂ entering arteries, less O₂ goes to veins

Question 7

What is CV drift?

Answer 7

A syndrome of CV destabilization during prolonged exercise that occurs w/ high workloads in hot environments

Question 8

What causes CV drift?

Answer 8

Decrease in preload associated w/ relocation of central blood volume to the skin to dissipate metabolic heat

Question 9

How does CV drift affect SV and systemic and pulmonary arterial pressure?

Answer 9

• Decreased SV
• Decreased pulmonary arterial pressure
• Decreased systematic arterial pressure

Question 10

What are the hemodynamic responses to dynamic exercise?

Answer 10

Question 11

What are the hemodynamic responses to static exercise?

Answer 11

Question 12

How does plasma volume change w/ training? Significance?

Answer 12

Increased plasma volume makes blood less viscous and easier to flow

Question 13

How do HR and BP adapt w/ training?

Answer 13

Decreases due to alterations in the balance b/t sympathetic and parasympathetic tone

Question 14

How does SV adapt w/ training? Why?

Answer 14

Increased SV due to:

• Reduced afterload (aortic pressure)
• Increased diastolic filling time (slower HR)
• Increased pressure of right atrial blood (volume load)

Question 15

What are the benefits of a slower HR?

Answer 15

​Allows more time for diastolic filling and coronary perfusion

Question 16

How is functional reserve altered w/ training?

Answer 16

Increased: can do same workload w/ less effort

Question 17

Define orthostasis.

Answer 17

Maintaining upright posture

Question 18

What is orthostatic hypotension? Symptoms? Cause?

Answer 18

• Shift of blood from head and heart to veins in legs upon standing
• Feeling of faintness due to sudden decrease in cerebral perfusion pressure due to reduced arterial blood pressure
• Most likely due to increased parasympathetic drive in trained athletes which leads to a slight delay in the autonomic nervous response upon standing

Question 19

What is concentric hypertrophy of the heart? Causes?

Answer 19

Response heart makes to chronic pressure loading (hypertension) in which the walls start to move toward center

Question 20

What is eccentric hypertrophy?

Answer 20

Wall thickens in proportion to increase in blood volume due to increased preload

Question 21

How are sarcomeres added in response to pressure load? What type of hypertrophy does this promote?

Answer 21

In parallel –> concentric hypertrophy

Question 22

How are sarcomeres added in response to volume load? What type of hypertrophy does this promote?

Answer 22

In series –> eccentric hypertrophy

Question 23

What constitutes normal, athletic hypertrophy of the heart?

Answer 23

• Adaptive
• Symmetric wall growth
• Reversible training effect
• Diastolic function is preserved