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 :
Original props of R2-D2 and C-3PO are used as audio-animatronics in the queue area of Disneyland 's Star ToursâThe Adventures Continue attraction.2-D2 was designed in artwork by Ralph McQuarrie and co-developed by John Stears but actually built by Tony Dyson, who ran his own studio called The White Horse Toy Company in the UK.