Why does isometric muscle contraction, while holding a heavy object stationary, still lead to muscle fatigue?

💡 Explanation

Isometric contraction causes fatigue due to the disruption of motor unit cycling. Specifically, some motor units are constantly active while others rest to maintain force. When cycling fails because active units become fatigued, contraction weakens; therefore motor unit cycling accounts for fatigue, rather than lack of ATP demand reduction.

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