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 :
Three convicts, Ulysses Everett McGill (George Clooney), known as Everett, Pete Hogwallop (John Turturro) and Delmar OâDonnel (Tim Blake Nelson) escape from a chain gang and set out to retrieve the $1.2 million that Everett buried. The three get a lift from a blind man driving a handcar on a railway.