Final answer:
During contraction, the myosin heads start in a high-energy state and end in a low-energy state after the power stroke. This allows the cross-bridge cycle to start again and continue muscle contraction.
Step-by-step explanation:
When the myosin head is cocked, it contains energy and is in a high-energy configuration. This energy is expended as the myosin head moves through the power stroke; at the end of the power stroke, the myosin head is in a low-energy position. After the power stroke, ADP is released; however, the cross-bridge formed is still in place, and actin and myosin are bound together. ATP can then attach to myosin, which allows the cross-bridge cycle to start again and further muscle contraction can occur.