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 :
The original girls were Farrah Fawcett-Majors as Jill Monroe, Kate Jackson as Sabrina Duncan and Jaclyn Smith as Kelly Garrett. They were my favourite line up in the show. Their bosses were John Bosley (played by the late David Doyle) and the faceless Charlie Townsend (voiced by John Forsythe).