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 :
Issac Ryan Brown. Issac Ryan Brown is one of the supporting actors of Devious Maids, portraying the role of Deion. Biography. Not much is known about Brown's life. In 2012, he appeared on season 7 of NBC's America's Got Talent. He was given a pass to Las Vegas by the show's three judges, but he was eliminated during the second round of competition.