Explain how stroke volume changes during a 45-minute moderate-intensity aerobic training session and why these changes occur. (4 marks)
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Sample Answer
- Stroke volume increases rapidly at the start of the session as the sympathetic nervous system activates, increasing heart contractility.
- The increase in stroke volume is due to increased venous return through the muscular pump mechanism.
- During steady-state exercise, stroke volume stabilises as cardiac output meets oxygen demands.
- During prolonged exercise, stroke volume may gradually decrease due to factors such as dehydration and reduced venous return.
- Post-exercise, stroke volume gradually returns to resting levels as the heart’s activity normalizes and returns to its pre-exercise state.
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Sample Answer
- Stroke volume increases rapidly at the start of the session as the sympathetic nervous system activates, increasing heart contractility.
- The increase in stroke volume is due to increased venous return through the muscular pump mechanism.
- During steady-state exercise, stroke volume stabilises as cardiac output meets oxygen demands.
- During prolonged exercise, stroke volume may gradually decrease due to factors such as dehydration and reduced venous return.
- Post-exercise, stroke volume gradually returns to resting levels as the heart’s activity normalizes and returns to its pre-exercise state.