Explain what happens to blood lactate levels during aerobic training of increasing intensity. (5 marks)
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- At rest, blood lactate levels remain low at approximately 1-2 mmol/L. This occurs because the aerobic system meets all energy demands without producing excess lactate.
- During light to moderate aerobic exercise, lactate production increases slightly as a result of increased energy demands. However, it remains in equilibrium with clearance due to sufficient oxygen availability.
- When exercise intensity increases to the aerobic threshold, lactate levels begin to rise gradually. The reason for this is that energy demands are approaching the capacity of the aerobic system, though the body can still manage lactate clearance effectively.
- At the lactate threshold/inflection point, lactate production exceeds the body’s ability to clear it. This happens because insufficient oxygen delivery forces a shift toward anaerobic metabolism.
- Beyond this point, lactate accumulates rapidly in the bloodstream. Consequently, increased muscle acidity develops, which leads to fatigue and limits performance duration.
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Sample Answer
- At rest, blood lactate levels remain low at approximately 1-2 mmol/L. This occurs because the aerobic system meets all energy demands without producing excess lactate.
- During light to moderate aerobic exercise, lactate production increases slightly as a result of increased energy demands. However, it remains in equilibrium with clearance due to sufficient oxygen availability.
- When exercise intensity increases to the aerobic threshold, lactate levels begin to rise gradually. The reason for this is that energy demands are approaching the capacity of the aerobic system, though the body can still manage lactate clearance effectively.
- At the lactate threshold/inflection point, lactate production exceeds the body’s ability to clear it. This happens because insufficient oxygen delivery forces a shift toward anaerobic metabolism.
- Beyond this point, lactate accumulates rapidly in the bloodstream. Consequently, increased muscle acidity develops, which leads to fatigue and limits performance duration.