Muscle memory would be ingrained into the mind’s perception of your bodies movement allowing you to move on reflex, its all ran from your brain, that is your perception and awareness, not your actual muscles having memory
It could be the red heart they got the werewolf dna from or it could just simply be blood or hair or something they found after the fight with quinn, to something as small as a dormant gene in some person or beast. Lol but yeah