During an experimental observation, a skeletal muscle fibre is stimulated and undergoes contraction. However, the muscle enters a state where the myosin heads remain firmly attached to the active sites on the actin filaments and fail to detach, preventing the muscle from relaxing. Which of the following biochemical conditions in the sarcoplasm best explains this inability to break the cross-bridges?

Step-by-step solution

According to the sliding filament theory of muscle contraction, the detachment of the myosin head from the actin filament strictly requires the binding of a new ATP molecule to the myosin head. If ATP is depleted in the sarcoplasm, the cross-bridges cannot be broken, and the myosin heads remain firmly attached to actin. This results in a state of sustained attachment, similar to rigor mortis. Continuous presence of high Ca ⁺⁺ ions or depletion of acetylcholinesterase would cause continuous cross-bridge cycling (rep