Analyse the relationship between stroke volume, heart rate and cardiac output during an aerobic training session. (6 marks)
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Sample Answer
- Cardiac output equals stroke volume multiplied by heart rate (CO = SV × HR)
- At the onset of exercise, both stroke volume and heart rate increase to elevate cardiac output
- Stroke volume increases due to increased venous return from active muscles and increased contractility of the heart
- Heart rate increases due to decreased parasympathetic and increased sympathetic stimulation
- As intensity increases, stroke volume reaches its maximum at moderate intensity (40-60% of maximum) and plateaus
- Further increases in cardiac output at higher intensities come primarily from increases in heart rate
- During steady-state exercise, cardiac output stabilizes as oxygen supply meets demand
- Recovery sees a gradual decrease in both heart rate and stroke volume, returning cardiac output to resting levels
- This relationship allows the cardiovascular system to efficiently meet the oxygen demands of working muscles during exercise
Show Worked Solution
Sample Answer
- Cardiac output equals stroke volume multiplied by heart rate (CO = SV × HR)
- At the onset of exercise, both stroke volume and heart rate increase to elevate cardiac output
- Stroke volume increases due to increased venous return from active muscles and increased contractility of the heart
- Heart rate increases due to decreased parasympathetic and increased sympathetic stimulation
- As intensity increases, stroke volume reaches its maximum at moderate intensity (40-60% of maximum) and plateaus
- Further increases in cardiac output at higher intensities come primarily from increases in heart rate
- During steady-state exercise, cardiac output stabilizes as oxygen supply meets demand
- Recovery sees a gradual decrease in both heart rate and stroke volume, returning cardiac output to resting levels
- This relationship allows the cardiovascular system to efficiently meet the oxygen demands of working muscles during exercise