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 :
Wayne Rogers who played beloved character Trapper John McIntyre on hit show M.A.S.H. dies aged 82 in Los Angeles. Wayne Rogers who played the beloved character Trapper John McIntyre on the popular show M.A.S.H. died on Thursday aged 82. Rogers' publicist Rona Menashe said the actor was surrounded by his family when he died in Los Angeles of complications from pneumonia. As army surgeon Trapper John on M.A.S.H., Rogers swapped wisecracks with partner in martinis-and-mischief Hawkeye Pierce, played by 79-year-old Alan Alda.