If you have a proper address position (again, the Fundamentals Trifecta comes into play in any discussion on the golf swing), the hips can play a very large factor providing the leverage needed to generate effortless power, even with irons.
In the iron swing photo below, you’ll see how much movement there is in my lower body, all with the intent of creating maximum leverage from the top of the back swing down through impact.
Once I’m at the top, it’s all about the hips moving to the target, the left foot compression and weight shift and everything else follows from there in a chain reaction. Also, look at the spine tilt to the right that naturally occurs with the hip action performed correctly.
There’s the classic “cranked at the top” position, even with the 7-iron that I’m swinging, and then the aggressive lower body and hip shift to the left.
To increase your power and club head acceleration, you only needed to make a more aggressive move with the hips on the down swing. The more aggressively you move them, the greater power you generate.
So a half-shot, a an 80% shot and a full-speed-ahead shot should all look the same except for the degree to which one moves the hips to the target. This is why people who use this method correctly never really look like they’re swinging out of their shoes.
They’re controlling the power and distance with the hip action, all the while remaining balanced and in control at the finish.