Cardiovascular Adaptations Learning Objectives (L21-22)

Question 1

What is the primary aim in CV responses to acute bouts of exercise?

Answer 1

Increase O2 delivery to skeletal muscle

Question 2

During exercise, heart rate increases proportionally to exercise intensity. What factors might affect the slope (relationship between intensity and HR) between individuals?

Answer 2

Fitness level

Question 3

What types of muscles correspond with higher heart rates when performing the same amount of work? Smaller or larger muscles?

Answer 3

Smaller muscles. More work is performed. More TPR due to smaller diameter of vessels.

The following is an explanation, we don’t need to know this
- Small muscle groups often require more intricate movements and finer motor control compared to large muscle groups.
- Small muscle groups may have a higher metabolic demand per unit of muscle mass compared to large muscle groups
- Large muscle groups, like those in the legs, are more efficient at performing work due to their size and strength. They can generate more force with less energy expenditure compared to smaller muscle groups.
- Smaller muscle groups may induce greater peripheral resistance due to the smaller diameter of blood vessels

Question 4

What types of contractions correspond with higher heart rates when performing the same amount of work? Dynamic or Isometric?

Answer 4

Dynamic. More work is performed.

Question 5

The PNS and SNS are divisions of the ANS that regulate HR. Which of the divisions is synonymous with ‘fight or flight’ and which with ‘rest and digest’?

Answer 5

SNS - Fight or flight
PSNS - Rest and digest

Question 6

What is the major hormone that modulates SNS activity to affect the ‘fight or flight’ system?

Answer 6

Adrenaline (and NA to a lesser extent)

Question 7

Beside the divisions of the ANS (SNS, PNS), what neurological components specifically regulate HR during exercise? (list 3)

Answer 7

• Input from the motor cortex
• Feedback from metaboreceptors in the muscles
• Modulation by baroreceptors

Question 8

What is are the CV: heart rate considerations for people with an artificial heart and a pacemaker. (i.e.: how is heart rate affected, why might this be the case?)

Answer 8

• No neural innervation of heart (at least initially)
• Heart paced (pacemaker)

Thus:
* HR increases during exercise only by circulating adrenaline
* HR increases are slow and modest vs neural control (hormones are slower than neural signals)

Question 9

What is the formula for SV?

Answer 9

SV = EDV-ESV

Question 10

What types of contractions correspond with higher stroke volumes when performing the same amount of work? Dynamic or Isometric?

Answer 10

Dynamic contractions. More work performed, more blood required to working muscles.

Question 11

What types of muscles correspond with higher stroke volumes when performing the same amount of work? Smaller or larger muscles?

Answer 11

Larger muscles. More work performed, more blood required to working muscles.

Question 12

What are the three mechanisms which enhance venous return during exercise and how much do they contribute to the system wide venous return?

Answer 12

Neural venoconstriction (minor)
Respiratory pump (modest)
Skeletal muscle pump (major)

Question 13

How does SPB and DPB change during the progression of a training/exercise session?

Answer 13

Immediate ↑ in SBP
Little ↑ in DBP (even slight fall) until near
maximal exercise in health peoples

Question 14

Of these exercises, which would cause the highest BP?

a) Rest
b) Aerobic Exercise
c) 2-arm bicep curl (heavy load)
d) 2-leg press (heavy load)

Answer 14

D

Question 15

BP increases in proportion to which 2 factors of heavy resistance training

Answer 15

Increases proportional to:
- workload, and
- duration of contraction

Question 16

What is the rate pressure product formula? What does it determine?

Answer 16

RPP = HR x SBP. Quantifiable measure of the workload on the myocardium

Question 17

How does total peripheral resistance change during dynamic exercise? How and why?

Answer 17

TPR decreases during dynamic exercise. Vasodilation occurs in active muscle beds (blood shunt mechanism to skeletal muscle).

Question 18

Are lower total peripheral resistance levels associated with larger or smaller working muscles?

Answer 18

Larger: require more O2.

Question 19

When exercising, does the brain receive more or less blood?

Answer 19

Slightly more

Question 20

Why is DBP generally lower when exercising?

Answer 20

There is less blood in the venous system due to an enhancing of venous return and increase in CO (less blood in the venous system ever at one time)

Question 21

How does blood supply to the myocardium change at rest and during exercise with respect to O2 demands? (i.e.: does it increase, decrease or remain the same)

Answer 21

Myocardium receives more blood during exercise but same % of blood with respect to O2 demands.

Question 22

Is vasoconstriction SNS or PNS mediated?

Answer 22

SNS

Question 23

Vasodilation in muscle vessels is both a) ____ (arterioles) and b) ____ (capillaries) mediated

Answer 23

a) SNS, b) locally

Question 24

What are the neural inputs that control CV function during exercise?

Answer 24

Motor cortex
Muscle metaboreceptors
Baroreceptors (arterial and C-P)

Question 25

What are the neural outputs that control CV function during exercise?

Answer 25

Change HR and SV
Vasoconstrict or vasodilate blood vessels

Question 26

The harder the exercise (greater the intensity), especially
dynamic exercise, the _______ the demands on the CV system

Answer 26

Greater

Question 27

Duration of exercise – for exercise longer than 30+ min
(especially in heat), get CV drift; ______ to maintain SV so HR
gradually increases

Answer 27

Harder

Question 28

The higher the level of physical fitness, the ______ the demands of
any absolute level of exercise on CV function

Answer 28

LessW

Question 29

What is the single main difference between physiological remodelling of the LV myocardium due to exercise and pathological remodelling (leading to heart failure) of the LV myocardium due to CVD

Answer 29

Thickening of LV walls vs Thinning of LV walls (due to myocardial ischemia, death of cardiac walls)

Question 30

What causes pathological LV wall damage?

Answer 30

Hypertrophic cardiomyopathy (due to the heart having to work harder, like in the case of a valvular disorder) or hypertension (due to the heart having to work harder to overcome resistance, like in the case of aortic resistance or coronoid artery disease)

Question 31

Both pathological and physiological remodelling of the LV myocardium causes hypertrophy. Why is it more concerning in pathological conditions rather than physiological conditions?

Answer 31

Main Concern: Increase in internal chamber size
Pathological changes cause fibrosis of myocardium and negatively impact the compliance. This means that the heart cannot distend properly when preload increases (directly opposite to physiological changes, which can functionally adapt and distend). Pathological remodelling decreases the internal chamber size and causes downstream consequences such as impaired preload, hypertension, pulmonary oedema and MI.

Question 32

What is the difference in pO2 demands to the myocardium at rest in trained athletes compared to untrained?

Answer 32

Myocardium is more efficient and less work is required at rest (O2 perfusion is more efficient), thus pO2/VO2 is lower during rest

Question 33

In highly trained athletes, why is less work required by the myocardium at sub-maximal intensities?

Answer 33

Coronary blood vessel changes:
- Increases blood flow to cardiac muscle
- Possible increase in collateral circulation
- Increased capacity to dilate coronary arteries
during exercise

Perfusion changes:
- Improvement in O2 perfusion

Question 34

Increases in blood volume occur after the body adapts to a period of aerobic training. How long does it take for RBCs to contribute to is adaptation?

Answer 34

3-4wks

Question 35

Is it normal for highly trained athletes to have lower than average HR (bradycardia)?

Answer 35

Yes. Common.

Question 36

Fill in the correct terms for stroke volume adaptations to aerobic training (Increase, Decrease, No change in):
________ resting stroke volume (SV)
________ submaximal exercise SV
________ maximal exercise SV

Answer 36

Increase
Increase
Increase

Question 37

Fill in the correct terms for TPR adaptations to aerobic training (Higher, Lower, Unchanged):
________ at rest
________ during submaximal exercise
________ during maximal exercise

Answer 37

Unchanged
Unchanged
Lower

Question 38

Fill in the correct terms for A-VO2 difference adaptations to aerobic training (Increase, Decrease, No change in):
________ during submaximal & maximal exercise
________ capillaries around muscle fibres
________ blood & oxygen delivery to fibres
________ myoglobin stores in muscle
________ diffusion of oxygen into muscle

Answer 38

Increase
Increase
Increase
Increase
Increase

Question 39

CV changes are observed with a) low-intensity, low-volume resistance training, or b) longer-term, high-volume resistance training?

Answer 39

B

Question 40

Using the formula for SV, explain why SV increases as an adaptation to aerobic exercise

Answer 40

Higher EDV: With more blood filling the heart (higher preload), and
Lower ESV: With more efficient ejection of blood (lower afterload),
Increased SV: The difference between EDV and ESV increases, resulting in a higher stroke volume (SV).

Question 41

What changes occur to RPP and BP as an adaptation to exercise in an individual at rest?

Answer 41

Lower RPP and BP at rest, may be due to lower peripheral resistance

Question 42

What changes occur to RPP and BP as an adaptation to exercise in an individual during exercise?

Answer 42

Often unchanged

Question 43

What changes occur to RPP and BP as an adaptation to exercise in a hypertensive individual after training and at rest? What types of exercise are best in order to cause this adaptation?

Answer 43

Normally decreases. Effects better with circuit training than conventional resistance training