Iron hip bump: sternum still, hips forward one inch
For iron shots, the speaker keeps his sternum still and simply shifts his hips forward about one inch. His checkpoint is for the outside of the trail hip to reach the inside of the trail foot, which he says creates a brace or post. He describes this as producing a slight secondary tilt that lets you turn behind the ball over the inside of the back foot without swaying off it.
Channel: PorzakGolf
Watch official source at 1:49Why this context matters
Applied specifically to iron shots, contrasted later with the driver.