Cardiorespiratory Responses to Exercise/Exercise Testing

Question 1

What is ATP?

Answer 1

ATP (adenosine triphosphate) is an energy rich compound for biological work. ATP sustains resting function for approx. 90s and exercise for approx. 60s

Question 2

ATP hydrolysis energy release equation

Answer 2

ATP + H2O → ADP + Pi + H+ + 7kcal of free energy/mol

Question 3

What are the three ATP creation pathways?

Answer 3

1. ATP-CP (anaerobic phosphagen) system
2. Glycolysis system
3. Oxidative phosphylation system

Question 4

DELETE

Question 4

Describe the ATP-CP system

Answer 4

Uses anaerobic mechanism, fueled by stored phosphagens, very limited capacity but very fast mechanism.
Phosphocreatine → creatine + PO3- + energy

Question 5

Describe the glycolysis system

Answer 5

Uses anaerobic mechanism, fueled by glycogen/glucose, limited capacity but fast mechanism.
Glycogen → pyruvic acid → lactic acid

Question 6

Describe the oxidative phosphylation system

Answer 6

Uses aerobic mechanism, fueled by glycogen, glucose, fats and proteins, unlimited capacity but slow mechanism

Question 7

Define oxygen consumption (VO2)

Answer 7

VO2 is the amount of O2 taken up by the lungs

Question 8

Define cellular oxygen consumption (QO2)

Answer 8

QO2 is the amount of oxygen taken up or consumed by the cells (e.g. skeletal muscle cells)

Question 9

Define maximal VO2 (VO2max)

Answer 9

VO2max is defined as the maximal volume of oxygen that a body can take up and use

Question 10

What is the Fick Equation?

Answer 10

VO2 = Q x (CaO2 – CVO2)

Question 11

What is the respiratory response to short term light-moderate constant workload exercise?

Answer 11

Phase 1: rapid increase in ventilation (approx. 1 second) - increase in Vt rather than RR
Phase 2: slower exponential rise (approx. 1 minute)
Phase 3: steady state

Question 12

What is the respiratory response to incremental exercise to maximum workload?

Answer 12

Minute ventilation (VE) increases with increasing workload, a ventilatory threshold is reached after which minute ventilation increases exponentially

Question 13

What is the cardiovascular response to short term light-moderate constant workload exercise?

Answer 13

As cardiac output (Q) increases, both heart rate (HR) and stroke volume (SV) increase, then plateau

Question 14

What is the cardiovascular response to incremental exercise to maximum workload?

Answer 14

Cardiac output increases linearly then plateaus. SV initially increases then plateaus. HR increases linearly to max HR

Question 15

What is heart rate recovery (HRR)?

Answer 15

The final stage of recovery post exercise, driven by parasympathetic reactivation and sympathetic inhibition

Question 16

What causes changes in HR?

Answer 16

Increases are caused by decreases in parasympathetic activity as well as increases in sympathetic activity. HR up to 100bpm is primarily due to vagal withdrawal, whereas HR over 100bpm is primarily due to sympathetic activation (neural drive supplemented by circulating catecholamines)

Question 17

What causes changes in stroke volume (SV)?

Answer 17

Changes in stroke volume (SV) are caused by an increase in sympathetic nerve activity, leading to:
- Increases in preload (venous return)
- Increases in contractility (increased SNA)
- Decreases in afterload

Question 18

Explain the effect of exercise on the lungs

Answer 18

Exercise has positive effects on the VO2max of individuals, particularly when moving from sedentary to active lifestyles

Question 19

Explain the effect of exercise on the heart

Answer 19

Central adjustments after training result in decreased heart rate and increased stroke volume to attain the same level of cardiac output as before

Question 20

Explain the effect of exercise on the muscles

Answer 20

Peripheral adjustments are when aerobic training leads to an increase in O2 delivery and extraction. To improve the delivery, muscle blood flow is increased. Hypertrophy of slow twitch fibres also occurs in muscle training adjustments. Skeletal muscle O2 extraction is improved by increases in capillary density, increases in myoglobin, increases in size and number of mitochondria, and increase in levels of oxidative enzymes