Cardiorespiratory Responses to Exercise/Exercise Testing Flashcards
What is ATP?
ATP (adenosine triphosphate) is an energy rich compound for biological work. ATP sustains resting function for approx. 90s and exercise for approx. 60s
ATP hydrolysis energy release equation
ATP + H2O → ADP + Pi + H+ + 7kcal of free energy/mol
What are the three ATP creation pathways?
- ATP-CP (anaerobic phosphagen) system
- Glycolysis system
- Oxidative phosphylation system
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Describe the ATP-CP system
Uses anaerobic mechanism, fueled by stored phosphagens, very limited capacity but very fast mechanism.
Phosphocreatine → creatine + PO3- + energy
Describe the glycolysis system
Uses anaerobic mechanism, fueled by glycogen/glucose, limited capacity but fast mechanism.
Glycogen → pyruvic acid → lactic acid
Describe the oxidative phosphylation system
Uses aerobic mechanism, fueled by glycogen, glucose, fats and proteins, unlimited capacity but slow mechanism
Define oxygen consumption (VO2)
VO2 is the amount of O2 taken up by the lungs
Define cellular oxygen consumption (QO2)
QO2 is the amount of oxygen taken up or consumed by the cells (e.g. skeletal muscle cells)
Define maximal VO2 (VO2max)
VO2max is defined as the maximal volume of oxygen that a body can take up and use
What is the Fick Equation?
VO2 = Q x (CaO2 – CVO2)
What is the respiratory response to short term light-moderate constant workload exercise?
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
What is the respiratory response to incremental exercise to maximum workload?
Minute ventilation (VE) increases with increasing workload, a ventilatory threshold is reached after which minute ventilation increases exponentially
What is the cardiovascular response to short term light-moderate constant workload exercise?
As cardiac output (Q) increases, both heart rate (HR) and stroke volume (SV) increase, then plateau
What is the cardiovascular response to incremental exercise to maximum workload?
Cardiac output increases linearly then plateaus. SV initially increases then plateaus. HR increases linearly to max HR
What is heart rate recovery (HRR)?
The final stage of recovery post exercise, driven by parasympathetic reactivation and sympathetic inhibition
What causes changes in HR?
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)
What causes changes in stroke volume (SV)?
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
Explain the effect of exercise on the lungs
Exercise has positive effects on the VO2max of individuals, particularly when moving from sedentary to active lifestyles
Explain the effect of exercise on the heart
Central adjustments after training result in decreased heart rate and increased stroke volume to attain the same level of cardiac output as before
Explain the effect of exercise on the muscles
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
