Does muscle contraction require ATP?

Yes, muscle contraction requires ATP. ATP is in fact a critical requirement for muscle contraction because it breaks the myosin-actin cross-bridge, freeing the myosin for the next contraction. Without ATP, muscles would remain in their contracted state, rather than their relaxed state.

Muscles contract and relax in a repetitive pattern of binding and releasing between the two thick and thin strands of sarcomere. With each contraction cycle, actin moves relative to myosin. ATP binds to myosin, moving it into a high-energy state and facilitating its binding with actin. During this reaction, ATP releases ADP and phosphate.

Once the myosin forms a cross-bridge with actin, the phosphate disassociates and the myosin undergoes a power stroke, reaching a lower state of energy when the sarcomere shortens. The released phosphate re-binds to ADP reconverting to ATP. The newly formed ATP molecule binds to myosin, breaking the cross-bridge between myosin and actin filaments, thereby releasing myosin for the next contraction.