Many modern golf instructors believe in restricting the hip turn in order to create tension and torque between the shoulders and hips, generating more power on the downswing.
Intentionally limiting hip turn isn’t recommended for senior golfers, however.
It takes great flexibility to make a full shoulder turn while holding back with the hips. And if there’s one thing seniors need in order to maintain power, it’s a good shoulder turn.
To ensure maximum upper body rotation, allow the left hip and knee to turn freely to the right on the backswing (for a right-handed golfer). It’s OK to allow the left knee to bend slightly inward, pointing to your right, as you reach the top. However, you should try to keep the left heel as close to the ground as possible to promote balance and stability. If you find it painful to keep the heel planted, allow it to rise a bit.
Remember, most advanced swing theories are aimed at young, supple golfers.
Seniors are allowed a little flexibility, if you will, in adapting their technique.