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 :
John C. Reilly Surprises David Letterman With Unexpected âGuardians of the Galaxyâ Clip (Video) John C. Reilly plays a member of the Nova Corp in Marvelâs upcoming âGuardians of the Galaxy.â Heâs the law enforcement officer who arrests the various members of the titular team, leading to their formation. He brought a clip with him from the movie â or at least a movie â for his appearance on âLate Show.â.