8. After pulling the actin as far as it can the myosin head releases from the binding site. New ATP molecules can attach to the myosin heads to power the next powerstroke of a contraction (Animation point 3). The myosin heads return to their original positions to be in readiness to re-attach to the uncovered binding sites.

9. The attachment-powerstroke-unattach sequence (Animation point 4) follows this cycle until the impulse ends and the calcium is reabsorbed by the SR, and the binding sites on the actin are covered.

For more information on this topic visit PE World's student resources and view the Sliding Filament Theory Presentation.