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 :
James MacArthur, who played Danno, the boyish-looking but hard-driving sidekick on the long-running television detective show Hawaii Five-O, died Thursday. He was 72. Mr. MacArthur died in Florida of natural causes, his agent, Richard Lewis, told the Associated Press. For 11 of the 12 years that Hawaii Five-O first ran on CBS, Mr. MacArthur, as Detective Danny Williams, chased thieves, hit men, swindlers, spies and assorted loonies.