Adaptations to Aerobic Training

Question 1

What happens to blood flow distribution during exercise?

Answer 1

1. increased Q (cardiac output) aka blood pumped per min through heart
2. BF is redistributed to accommodate active skeletal muscle

Question 2

What is the intrinsic pacemaker of the heart?

Answer 2

SA (Sinoatrial Node)

Question 3

What is the inherent rhythm of the SA Node?

Answer 3

100 bpm

Question 4

Describe Parasympathetic tone

Answer 4

Vagus nerve is stimulated, reaches SA/AV node, releases ACH which decreases activity & HR

Question 5

Describe Sympathetic tone

Answer 5

Cardiac Accelerator nerves innervate SA node/ventricles which signals the release of Catecholamines (epi/norepi), which increases SA node depolarization/HR

Question 6

What is responsible for the initial increase in HR during a bout of exercise

Answer 6

Vagal Withdrawal (aka a decrease in parasympathetic tone)

Question 7

What is the Frank-Starling Mechanism

Answer 7

an increase in diastolic volume stretches the cardiac muscle fibers and therefore increases the force of contraction

Question 8

How does the body auto-regulate during exercise?

Answer 8

decrease in O2 in tissues stimulates vasodilation in working muscles, (+) in core temp, increase in CO2/acidity, Adenosine, MG, K+, Nitric Oxide in blood vessels, Sympathetic response shifts blood flow to exercising muscle and away from the Viscera

Question 9

What happens to Systolic blood pressure during exercise? And Why?

Answer 9

It rises due to:

1. increased HR/SV
2. Muscle action/greater force required
3. Vasodilation of exercising muscles allows more BF to drain from arteries

Question 10

What happens to Diastolic blood pressure during exercise?

Answer 10

Should not change or decrease slightly

Question 11

How does blood flow distribution during exercise change in the muscle?

Answer 11

15-20% at rest, 84% at max

Question 12

How does blood flow distribution during exercise change in the liver?

Answer 12

27% at rest, 2% at max

Question 13

How does blood flow distribution during exercise change in the Heart?

Answer 13

4% at rest and max

Question 14

How does blood flow distribution during exercise change in the Skin?

Answer 14

6% at rest, 2% max

Question 15

How does blood flow distribution during exercise change in the brain?

Answer 15

14% at rest, 4% max (absolute BV slightly higher due to Q)

Question 16

How does blood flow distribution during exercise change in the kidneys?

Answer 16

22% at rest, 1% at max

Question 17

What happens to blood volume at the onset of exercise? and Why?

Answer 17

BV decreases 10-20% because:

1. hydrostatic pressure from muscular contraction squeezes fluid from bloodstream
2. increase in osmotic pressure in intersititial fluid space around muscle cells due to accumulation of metabolites
3. fluid lost to sweat

Question 18

How does the body preserve blood volume during exercise?

Answer 18

1. increase HR to maintain Q and offset small initial loss in SV
2. Vasoconstriction of non-exercising muscle to maintain peripheral resistance
3. release of hormones: Vasopressin/Adosterone to decrease water/NA+ loss from body

Question 19

Define transient hypertrophy

Answer 19

the “pump” which results from fluid build-up (aka Edema) in interstitial and intracellular spaces of muscle from blood plasma

Question 20

What is the limiting factor of Cardiac output during exercise

Answer 20

Venous Return (the rate of blood flow back to the heart)

Question 21

What happens to Venous Return during isometric exercises?

Answer 21

VR decreases as the pump that sends back to the heart via contractions/one way valves is inhibited (this happens during weight lifting)

Question 22

What is ventilation, and why does it increase right before exercise even begins?

Answer 22

Ventilation= volume of air breathed per minute

Catecholamines are responsible for increase in breathing rate

Question 23

What is the humeral effect of ventilation?

Answer 23

receptors in the brain, carotid and aortic arteries sense chemical changes in blood (CO2, H+, K+) and responds by increasing ventilation

Question 24

What is the neural effect of ventilation?

Answer 24

receptors in Medulla sense working muscle (or decrease in O2) via muscle spindles, GTOs, joint pressure receptors, and POSSIBLY mechanoreceptors in R ventricle

Question 25

How does chronic aerobic exercise affect blood volume?

Answer 25

Increases (mainly plasma) up 12-20%

Question 26

How does exercise affect the side of the heart?

Answer 26

L ventricle gets a little thicker (especially with resistance training)/bigger/more efficient (Frank-Starling Mechanism)

Question 27

How does exercise affect the size of the heart?

Answer 27

10 bpm slower at rest, 20 bpm slower at sub-max, same at max

Question 28

Chronic Adaptations of SV

Answer 28

increase at rest, sub-max, and max

Question 29

Chronic Adaptations of Q

Answer 29

same or slightly decrease at rest/sub-max, increase at max w/ aerobic training (due to increase in SV)

Question 30

Chronic Adaptations of AVO2 diff/explain

Answer 30

LOWER mixed venous O2 content because of

1. greater O2 extraction at tissue level
2. more efficient BF distribution to active tissue

Question 31

Chronic Adaptations of BF

Answer 31

more BF to active tissue due to increased capillarization of trained muscle- new ones, existing ones get bigger, increased BV

Question 32

Chronic Adaptions of BP

Answer 32

wont change much for normal, but can slightly decrease for pre/hypertensive

Question 33

Chronic Adaptations to Neurons (3)

Answer 33

1. motor unit recruitment- increased ability to contract simultaneously (usually recruits type 1 then type 2) and
2. rate coding- faster time to peak force production of the MU
3. Decreased co-activation of antagonist muscle