During a sustained maximal voluntary contraction, why does muscle fiber failure, characterized by a decline in force output, occur even though neural drive remains maximal?

💡 Explanation

Muscle fiber failure occurs because the accumulation of lactate and hydrogen ions during intense contraction reduces intracellular pH, inhibiting cross-bridge cycling and force production. Therefore, the impaired cross-bridge function, not calcium handling or neurotransmitter release, explains the decline; rather than neural drive failure, it's metabolic failure.

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