An udarnik (/uːˈdɑːrnɪk/,[1] plural udarniks or udarniki; Russian: уда́рник, IPA: [ʊˈdarnʲɪk]), also known in English as a shock worker[2] or strike worker (collectively known as shock brigades[3] or a shock labor team[4]) was a term used to refer to a supposedly high productivity worker. The term was mainly used in the Soviet Union, the Eastern Bloc, and other communist countries. It derived from the expression "udarny trud" for "superproductive, enthusiastic labor".[5]