An MTA worker was punched in the face when he chided a dumbbell for doing pull-ups on a subway car in Queens, police said Thursday.

The suspect was working out using the bars on an N train as it was sitting at the Ditmars Boulevard terminal, when the 64-year-old transit employee told him to stop what he was doing around 1:10 p.m. Aug. 9.

The disgruntled passenger then socked the worker in the face and ran off the train, police said.

The suspect is believed to be in his early 20s, has short black hair and was last seen wearing a black short-sleeved shirt, blue jeans and black sneakers.