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 :
Po is the fourth Teletubby. She lives with the other Teletubbies in the Superdome. Po is a rosy red Teletubby whom has an antenna that is shaped like a circle used for blowing bubbles. She is the smallest of the Teletubbies. Po is 6 feet tall and she is played by Pui Fan Lee in the original series (Rachelle Beinart in the new series), who is a British actress of Chinese descent and is also a popular presenter, which is why Po can speak in English and Cantonese. Fi dit! is Cantonese for Faster!.