Activation of myosin phosphatase increases the cycling frequency of myosin heads by accelerating their detachment and reattachment to actin, resulting in more rapid muscle contractions. This requires the hydrolysis of ATP to provide the necessary energy for each cross-bridge cycle.
When myosin phosphatase is strongly activated along with myosin kinase, the frequency of cross-bridge cycling increases. This means that myosin heads attach to actin more frequently, perform the power stroke, release, and reattach to pull actin again in a recurring cycle. The cycling speed is critical for muscle contraction and is influenced by how quickly myosin ATPase can hydrolyze ATP. With efficient activation of myosin phosphatase, the detachment of myosin heads from actin after a power stroke is expedited, allowing for more rapid reattachment and another round of pulling, which in turn increases overall muscle contraction speed and efficiency.
This process is enhanced by ATP hydrolysis, which provides the energy necessary for the myosin heads to move, attach, pull, and then release the actin filaments. The re-cocking of the myosin head, a key part of the cycle, requires ATP to be split into adenosine diphosphate (ADP) and inorganic phosphate (Pi), with the energy released being used to prime the myosin head for another cycle.