Muscles relax following contraction through the active reuptake of calcium ions into the sarcoplasmic reticulum (primarily via SERCA pumps) and the binding of ATP to detach actomyosin cross-bridges. No citation is strictly needed as this is a fundamental physiological fact, but retrieved literature thoroughly supports these mechanisms.
The claim describes well-established physiological principles regarding muscle relaxation (calcium reuptake by SERCA pumps and ATP binding for cross-bridge detachment). Although it is basic physiological knowledge (Common Knowledge), several retrieved papers directly bear upon these mechanisms (e.g., papers 0, 3, and 10 discuss SERCA-mediated calcium reuptake and ATP-dependent cross-bridge detachment). Therefore, the balance verdict is set to COMMON_KNOWLEDGE while accurately capturing the supporting literature.