During intense exercise, why does skeletal muscle fatigue accelerate if phosphofructokinase (PFK) activity declines due to accumulating intracellular hydrogen ions?

💡 Explanation

A decline in PFK activity reduces the glycolytic flux, and therefore the rate of ATP resynthesis, because PFK catalyzes a key step in glycolysis. This causes fatigue to accelerate due to energy supply limitations, rather than through other pathways.

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