Exercise for Rehabilitation and Training

Question 1

By how much can cardiac output increase during exercise?

Answer 1

From 1L/min to 22L/min.

Question 2

List 3 points where the transport of oxygen from the lungs to the mitochondria can be limited.

Answer 2

1 - Oxygen uptake in the lungs (VO2 max).

2 - Cell perfusion.

3 - Diffusion into cells.

Question 3

List 2 cardiovascular factors which limit oxygen uptake in the lungs (VO2 max).

Answer 3

1 - Maximum achievable cardiac output.

2 - Haematocrit.

Question 4

What proportion of oxygen in the blood is carried by red blood cells?

Answer 4

98.5%.

Question 5

What is the resting oxygen uptake in the lungs?

Answer 5

250ml/min.

Question 6

Describe the types of cardiac hypertrophy.

Answer 6

1 - Concentric hypertrophy. Characterised by a thicker wall and smaller ventricular chamber.

2 - Eccentric hypertrophy. Characterised by a constant wall thickness but larger ventricular chamber.

Question 7

How are sarcomeres arranged in concentric hypertrophy?

Answer 7

In parallel.

Question 8

How are sarcomeres arranged in eccentric hypertrophy?

Answer 8

In series.

Question 9

How does each type of cardiac hypertrophy affect stroke volume?

Why does this occur?

Answer 9

• Concentric hypertrophy decreases stroke volume.
• Eccentric hypertrophy increases stroke volume.
• This is due to changes in inotropy and EDV.

Question 10

When might concentric hypertrophy occur?

Answer 10

Due to hypertension.

Question 11

Which growth factor causes eccentric hypertrophy?

When is this growth factor released?

Answer 11

• Insulin-like growth factor.

- It is released during exercise.

Question 12

How does an increase in inotropy affect the starling curve?

Answer 12

The curve is shifted upwards and maintains its shape.

Question 13

What is Laplace’s law?

Answer 13

P = 2T / r

Where P = pressure, T = surface tension and r = radius.

Question 14

What is the effect of Laplace’s law on stroke volume in hypertrophied hearts?

Answer 14

• The change in pressure due to changes in radius (Laplace’s law) is offset by changes in inotropy.
• In a concentric heart, although systolic pressure increases according to Laplace’s law, the decrease in inotropy means that the overall effect is a decrease systolic pressure.
• In an eccentric heart, although systolic pressure decreases according to laplace’s law, the increase in inotropy means that the overall effect is an increase in systolic pressure.

Question 15

List 3 reasons that explain why EDV changes with cardiac hypertrophy.

Answer 15

1 - Chamber volume changes.

2 - Circulating blood volume increases with exercise training.

3 - Central venous pressure changes.

Question 16

Other than increasing stroke volume, how does exercise training affect heart activity?

How does this come about?

Answer 16

• Heart rate is decreased (to maintain the same cardiac output as an individual with lower inotropy).

This comes about by:

1 - Increased vagal activity.

2 - Increased local ACh release from parasympathetic innervation.

3 - Decreased intrinsic pacemaker activity.

Question 17

Which components of the heart receive sympathetic innervation?

Which components of the heart receive parasympathetic innervation?

Answer 17

• The SAN, AVN and ventricular muscle receive sympathetic innervation.
• The SAN and AVN receive parasympathetic innervation.

Question 18

What is the capillary:cardiac myocyte ratio in a normal heart?

Answer 18

1

Question 19

How does exercise training affect the capillary:cardiac myocyte ratio?

What might offset the effect of this?

Answer 19

• It increases.

- The increase in cardiac myocyte size offsets the effect of this increase.

Question 20

Other than changes to the capillary:cardiac myocyte ratio, list the changes in vascular supply to the heart that occur with exercise training.

Answer 20

1 - Increased number of arterioles.

2 - Increased coronary artery diameter.

Question 21

List the changes in vascular supply to skeletal muscle that occur with exercise training.

Answer 21

1 - Increased number of capillaries.

2 - Increased artery diameter.

Question 22

Define conduit artery.

Answer 22

An elastic artery with many collagen and elastin filaments in the tunica media which give it the ability to stretch in response to each pulse.

Question 23

Which growth factor causes angiogenesis?

When is this growth factor released?

Answer 23

• Vascular endothelial growth factor.

- It is released as a result of activation of hypoxic-inducible factor, which occurs in response to hypoxia.

Question 24

List 4 changes in skeletal muscle that occur with exercise training.

Answer 24

1 - Increased mitochondria density in skeletal myocytes.

2 - Upregulation of endothelial nitric oxide synthase (eNOS) in the endothelium.

3 - Upregulation of antioxidant enzymes in the endothelium.

4 - Increased muscle myoglobin.

Question 25

What is the advantage of an increase in bioavailability of nitric oxide?

Answer 25

It is a potent vasodilator, so reduces TPR and therefore decreases cardiac work.

Question 26

Why does training at altitude increase maximum oxygen uptake (VO2 max)?

Answer 26

Training at altitude can stimulate erythropoiesis and therefore change the haematocrit.

Question 27

What effect does ROS have on blood vessels?

Answer 27

ROS causes vasoconstriction.

Question 28

List the two mechanisms targeted by cardiovascular rehabilitation.

Answer 28

1 - Changes in the balance of autonomic activity to decrease sympathetic activity and increase parasympathetic activity.

2 - Changes in blood vessel dilator function to decrease ROS and increase nitric oxide.

Question 29

List 5 objectives of cardiovascular rehabilitation.

Answer 29

1 - To reduce hypertension.

2 - To reduce atherosclerosis.

3 - To improve coronary artery disease.

4 - To induce eccentric hypertrophy.

5 - To increase inotropy.

Question 30

List 3 NICE guidelines on exercise for people at high risk of, or with, cardiovascular disease.

Answer 30

1 - At least 150 minutes of moderate intensity aerobic activity.

2 - 75 minutes of vigorous aerobic activity.

3 - Muscle strengthening activity on 2 or more days per week.

Question 31

List 5 long term benefits of exercise.

Answer 31

1 - Improves cholesterol.

2 - Controls body weight and shape.

3 - Reduces diabetes risk.

4 - Reduces stress.

5 - Boosts confidence.