In a laboratory experiment, a skeletal muscle fibre is treated with a specific chemical inhibitor that selectively prevents the binding of a new ATP molecule to the myosin head, without affecting calcium release or the initial hydrolysis of previously bound ATP. If a neural stimulus is applied to this muscle fibre, at which exact stage will the contraction cycle arrest?

Step-by-step solution

During muscle contraction, the energy derived from the hydrolysis of ATP is used to form a cross-bridge between the myosin head and the exposed active site on actin, which is then followed by the power stroke. According to the sliding filament theory, for the myosin head to detach from the actin filament and return to its relaxed state, a new ATP molecule must bind to it. If a chemical inhibitor prevents the binding of this new ATP, the cross-bridge cannot be broken. Consequently, the contraction cycle will arrest