Final answer:
The power stroke in both smooth and skeletal muscles occurs when ADP and phosphate dissociate from the actin active site.
Step-by-step explanation:
The power stroke is the same in smooth and skeletal muscles because it occurs when ADP and phosphate dissociate from the actin active site.
When the power stroke happens, the actin head bends, causing muscle contraction.
Another ATP then binds to the myosin head, causing the cross-bridge to detach and allowing the muscle to return to its initial state.