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 :
Alpo, who is from Spanish Harlem, once ran the streets with Azie âAZâ Faison and Rich Porter and the trio amassed a drug empire that continues to spawn street tales to this day. The most infamous re-telling happened in the movie Paid In Full, by Roc-A-Fella Films.