Not yet investigated
What we have so far
Muscle's stem cells, sitting dormant under the basal lamina. They donate nuclei to a fibre after damage, and those nuclei may be what 'muscle memory' actually is.
This star is on the map because the show intends to take the question apart properly — the trials, how it is actually tested, whether the thing sold is the thing studied. That work is not done yet, and nothing here should be read as a conclusion. When the investigation is published it will appear on this page.