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 :
Known as El Chapo (Shorty, pronounced [el ËtÊapo]) for his 168 cm (5 ft 6 in) stature), he became Mexico's top drug kingpin in 2003 after the arrest of his rival Osiel CÃ¡rdenas GuillÃ©n of the Gulf Cartel, and was considered the most powerful drug trafficker in the world by the United States Department of the Treasury.