Several years ago I helped remove an old cast-iron radiator from our church. It was a tube-type unit about 30 inches tall and at least 6 feet long. When I got there the unit was lying on the floor and simply needed to be "thrown" onto a waiting truck.
Never having had a close encounter with a similar unit, I squatted down, grabbed hold of one leg, straightened my back, and pushed hard with both legs. That radiator didn't move one millimeter.