Golf Swing: Left Leg straightens

Must maintain LSB right. Left leg straightens but you remain in posture (bent over at the hips)

I find that using the left glute to straighten left leg adds snapping rotational power coming into impact vs. simply using the left quad to straighten the left leg

The left leg straightens thru impact but it is the left hip that extends it ...not so much the left hamstring ....using the left hip this way adds more whipping power into the bowed hip / elbow / wrist construction ...and also it stops placement of your weight on the ball of your left foot ....and keeps it on your left heel where it should be.

....but do not straighten the right leg !!