An Olympic weightlifter attempting a record-breaking lift experiences rapid muscle fatigue. Which mechanism is most likely limiting force generation, assuming adequate calcium is present?

💡 Explanation

Muscle fatigue during intense exertion is often due to inorganic phosphate (Pi) accumulation from ATP hydrolysis. Pi accumulation directly inhibits myosin ATPase activity, reducing cross-bridge cycling, because it binds to the myosin head, therefore reducing the power stroke. This effect dominates, rather than altered glycogenolysis, creatine phosphate, or potassium dynamics, under high-intensity conditions with adequate calcium.

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