This must be a wrong link because the word memory and the word muscle do not appear in the text.
And however you want to call it the effect exists. I had my body ran away with a piece of music without thinking about it. And yes your brain is likely still involved in some way but that is not the point in this context.
And it has nothing to do with the immune system.
reread the first passage,"the study of the interaction between psychological processes and the nervous and immune systems of the human body." on everything it dabbles in and everything it includes."incorporating psychology, neuroscience, immunology, physiology, genetics, pharmacology, molecular biology, psychiatry, behavioral medicine, infectious diseases, endocrinology, and rheumatology." The word muscle memory wouldn't appear, because it does not exist.. go on Facebook, look up Yost Wing Chun, and ask mister Jason Yost what muscle memory really is.