Module 6: Cardiorespiratory Integration & Adaptation to Training

Question 1

What does the A-VO2 difference represent?

Answer 1

Amount of oxygen taken up from blood by the metabolically active tissues

Question 2

What is the A-VO2 difference in skeletal muscle at rest?

Answer 2

A-VO2 difference:
= CaO2 - CvO2
= 200 mL/L - 150 mL/L
= 50 ml/L

Question 3

What is the A-VO2 difference in skeletal muscle during intense exercise?

Answer 3

A-VO2 difference:
= CaO2 - CvO2
= 200 mL/L - 50 mL/L
= 150 mL/L

Question 4

What is the fick equation and what does it represent?

Answer 4

VO2 = Q X A-VO2 difference
The volume of oxygen consumption of a tissue = the product of cardiac output and the arterial-venous difference

Question 5

What is the average VO2 of an individual at rest?

Answer 5

VO2 = Q X A-VO2 difference
VO2 = 5 L/min (average cardiac output at rest) x 50 mL O2/L
VO2 = 250 mL O2/min
VO2 = 0.25 L O2/min

Question 6

What is the average VO2 of an individual at maximal exercise?

Answer 6

VO2 = Q X A-VO2 difference
VO2 = 20 L/min (average cardiac output at maximal effort) x 150 mL O2/min
VO2 = 3000 mL O2/min
VO2 = 3 L O2/min

Question 7

What are the cardiovascular responses to acute exercise?

Answer 7

Muscle contraction stimulates local factors, CV control centers, and an increased venous return

Local factors (functional sympatholysis) -> local vasodilation in active tissue which is contracting -> increased O2 extraction

CV control centers > increase the stimulation of SNS (increase in HR and SV which increases Q contributing to increased muscle blood flow, promotes splanchnic vasoconstriction of less active tissues which contributes to increased muscle blood flow) and decrease the stimulation of the PNS (Anticipatory increase in HR)

Increased venous return -> increased EDV -> increased SV (frank starling law)

Question 8

What is the definition of blood pressure? What are the two primary determinants of it? Equation?

Answer 8

Average force exerted by blood against vasculature
1. Cardiac output (Q)
2. Peripheral resistance

Pressure = flow (cardiac output) x resistance

Question 9

At rest, if cardiac output (Q) is increased, how is pressure influenced?

Answer 9

Pressure = flow x resistance
Increased flow = increased pressure

Question 10

At rest, if vasodilation of the vasculature occurs, how is pressure influenced?

Answer 10

Pressure = flow x resistance
Decreased resistance = decreased pressure

Question 11

At rest, if vasoconstriction of the vasculature occurs, how is pressure influenced?

Answer 11

Pressure = flow x resistance
Increased resistance = increased pressure

Question 12

What is the definition of Mean Arterial Pressure (MAP)? Equation?

Answer 12

The average driving pressure during the cardiac cycle

MAP (also known as pulse pressure: PP) = DBP + 1/3 (SBP-DBP)

Question 13

At rest, what is the average SBP, DBP, and MAP of an individual @ rest?

Answer 13

SBP/DBP = 120/80 mmHg
MAP = 80 + 1/3 (120 - 80)
MAP = 93 mmHg

Question 14

How is BP influenced by aerobic exercise (i.e., running, swimming, cycling)?

Answer 14

Increase in SBP (pressure in the arteries when the left ventricle contracts) - associated with increased cardiac output (5 L/min to 20 L/min during exercise), does not increase with the same magnitude as cardiac output which can be associated with decrease resistance, can go up from 120 to 200 mmHg
No change in DBP (pressure in the arteries when the heart is resting) -
Slight increase in MAP - associated with an increase in SBP

Question 15

How is BP influenced by resistance exercise (i.e., weightlifting)?

Answer 15

A dramatic increase in both SBP and DBP, thus a dramatic increase in MAP - associated with the valsalva maneuver which is essentially exhaling while the mouth, and nose are closed -> increased intra thoracic pressure -> increased BP

This maneuver explains why some individuals can experience a heart attack while shoveling snow

Question 16

What is the equation that is utilized to estimate the workload of the heart?

Answer 16

Rate-pressure product: HR X SBP

Question 17

How does SBP compare in individuals performing aerobic exercise, hypertensive individuals performing exercise, and individuals performing resistance exercise?

Answer 17

SBP for aerobic exercise: 150 mmHg
SBP for hypertensive individuals performing exercise: 200 mmHg -> Increase of RPP by ~30% @HR of 140 BPM
SBP for resistance exercise : 400 mmHg -> Increase of RPP by ~>150% @HR of 140 BPM

Question 18

What is the equation of hemodynamics?

Answer 18

Flow = Pressure change / resistance
Q = MAP / TPR
TPR = MAP / Q

Question 19

What is the normative value for TPR at rest at the whole body level? How does it change during intense aerobic exercise?

Answer 19

At rest:
19 mmHg/L/min

TPR = MAP/Q
Q = 5 L/min
MAP = 93 mmHg
TPR = 93 mmHg / 5 L/min
TPR = 18.6 mmHg/L/min which is rounded

Intense exercise:
5 mmHg/L/min

TPR =MAP/Q
MAP = ~120 mmHg
Q = 25 L/min
TPR = 120 mmHg/25L/min
TPR = 4.8 mmHg/L/min which is rounded

Changes from rest to exercise:
- 5x increase in cardiac output
- MAP increases 30%
- 4x decrease in TPR

Question 19

How much muscle blood flow increase during exercise?

Answer 19

1. Active tissues: vasodilation -> decreased resistance -> more blood flow
2. Less active tissues: vasoconstriction -> increased resistance -> less blood flow

Cardiac output is redirected to where it is needed

Question 20

What are the cardiorespiratory adaptations to training (absolute vs relative)?

Answer 20

1. Increase in VO2 max (12-week training program -> increase of ~20% in ones VO2 max) and workload that an individual is able to perform

At the same absolute workload (i.e., 210 W), a trained individual will have a easier time performing the exercise (reflects lower % of maximum effort), VO2 between an untrained and trained individual is the same

At the same relative workload (i.e., 70% of VO2 max), a trained individual will be able to produce a greater workload, subsequently requiring more O2 (+VO2) to generate more ATP

Question 21

What are the two categories of factors which can influence one’s VO2 max?

Answer 21

1. Central limitations (any factor that affects O2 delivery to the muscles)
   Maximal cardiac output (major central determinant), optimal gas exchange at the lungs, the ability of the blood to carry oxygen
2. Peripheral limitations (any factor that affects O2 utilization by the muscles)
   Mitochondrial content, capillerization of muscle fibers (most important peripheral determinant)

Question 22

What are the four factors which influence CaO2 and CvO2?

Answer 22

CaO2: [Hgb] and saturation
CvO2: capillarization and mitochondrial content

Question 23

How does HR differ in untrained, trained, and elite individuals during submaximal exercise?

Answer 23

Untrained individual: HR spikes quickly over the duration of exercise
Trained individual: lower resting HR, HR does not increase as quickly over the duration of exercise
Elite individual: very low resting HR, HR increases very slowly

Question 24

How does SV differ in untrained, trained, and elite individuals during submaximal exercise?

Answer 24

Untrained individual: low SV
Trained individual: higher SV for every intensity, SV duration increases
Elite individual: highest SV for every intensity, highest SV duration

As one progresses, SV max increases

Question 25

How does HR differ in untrained and trained individuals during maximal exercise?

Answer 25

HR max does not change - it takes a greater workload for a trained individual to reach that HR relative to an untrained individual

Question 26

How does SV differ in untrained and trained individuals during maximal exercise?

Answer 26

Untrained individual: SV plateaus at around 50% of maximal workload
Trained individual: SV progressively increases allowing a greater SV max

Question 27

How does cardiac output differ in untrained, trained, and elite individuals during submaximal exercise?

Answer 27

The cardiac output does not change, the way its achieved changes

Untrained: SV, HR
Trained: Higher SV, lower HR
Elite: Highest SV, lowest HR

Question 28

How does cardiac output differ in untrained, trained, and elite individuals during maximal exercise?

Answer 28

Maximal cardiac output increases with training (Increased SV max = increased Q)

Question 29

How do you calculate SV? What causes an increase in SV during submaximal and maximal training?

Answer 29

SV = EDV - ESV

Increased EDV (filling of the heart) - associated with greater filling time during diastole, increased blood volume, increased preload (frank starling law)

Decreased ESV (blood ejected) - associated with increased left ventricular mass, less peripheral resistance

Question 30

How does blood change with exercise training?

Answer 30

Increase in haemoglobin from increases in RBC’s, and plasma in blood with training

Question 31

How does the muscle A-VO2 difference change with training?

Answer 31

Increases (~3%)

A-VO2 difference: CaO2-CvO2
CaO2 is influenced by [Hgb] and % saturation of Hgb (~98%)
CaO2 does not really change

CvO2 is heavily influenced by capillary density, some by mitochondrial content
Greater O2 extraction - is associated with increased capillary density, increased transit time of RBC, increased time available for O2 release
CvO2 becomes less

Question 32

What is the main reason why VO2 max increases with exercise training?

Answer 32

SV max (~15% increase with training)

Question 33

What is a normative VO2 max value pre-training and post-training?

Answer 33

Pre: 3.0 L/min
Post: 3.6 L/min