Kim Jong Kook reminded fans why he's known as 'Sparta' on 'Running Man' by revealing his impressive, muscular legs.

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On November 26, Kim Jong Kook posted the below photo along with the message, "Don't skip leg day!" It looks like the Turbo member and 'Running Man' star is hitting the gym with no rest after he, HaHa, and Skull returned from Las Vegas, Nevada, where they held the 'Running Man Bros. Concert'.

Take a look at Kim Jong Kook's unbelievably buff legs below!