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 :
(CNN) -- Sorry, Screech, but Zack thinks you are wrong. Mark-Paul Gosselaar, who played Zack Morris on the cult classic '90s TV show Saved by the Bell, doesn't agree with former co-star Dustin Diamond's portrayal of their time together. Diamond -- who played super nerdy Samuel Screech Powers -- put out a book years ago titled Behind the Bell.. Now there's a Lifetime TV movie, The Unauthorized Saved by the Bell Story, which purports to show the less-than-glamorous side of life on the show, complete with fights, jealousy and other drama.