In 1980 Alberca et al. described a patient with a syndrome of increased muscle irritability, who presented ondulating muscle rolling movements and electrically silent cramps, myoedema and muscle reactions to mechanical stimulation similar to myotonic response, suggesting a disfunction at myofibrillar level.
For c-3po, it was a costume, Anthony Daniels played c-3po: For R2-D2, It was a costume and a remote controlled robot. CGI was also used in the prequel trilogy. So, they had Kenny Baker to play him : And from Portrayal section of wookieepedia article on R2-D2 :
[Jeanne Tripplehorn](http://glamour.com/about/jeanne-tripplehorn) played Jackie in *Grey Gardens*, and besides the way she nailed the whole head-scarf-sunnies-pout combo, there's the fact that she's Jeanne Tripplehorn and everything she does is my favorite. [#iframe:http://www.youtube.com/embed/cZ4kYk2ITXs](420x315)