When you should drive off the rear leg to produce power in the swing is often debated. This applies to not only to the swing in golf but also to baseball, tennis and other sports in which you swing an implement to hit a ball or other object. According to some professional instructors you should drive off your rear leg late in the swing to produce more forward weight shift.
This ‘springboard effect’ as they call it, supplies extra clubhead, bat or racket speed and ultimately more power and/or distance. Is this, however, a sound recommendation? Does driving off the rear leg to shift weight forward late in the swing really add more power or distance or does it interfere with accuracy and force?
For example, this recommendation is contrary to what occurs in executing an effective swing or hit as determined by physics (biomechanics) and swing technique analyses. It has been well substantiated that the drive off the rear leg occurs at the beginning of the power phase of the swing (when you generate the force needed in execution of the skill).
This force, produced by shifting the hips forward, is usually directed toward the target and initiated after completion of the backswing. The drive off the rear leg is partially responsible for this force but mostly it comes from hip abduction in order to shift the hips forward to initiate the downswing in golf or forward swing in baseball and tennis. In this action weight from the rear leg is transferred to the front leg as the hips are driven forward.
This action is commonly known as weight shift and is the first action to generate force in the power phase. In other words, the hips come through early in the swing to set up the kinetic chain actions that follow in sequence. If you drive the hips forward after you are well into the power phase it will contribute very little, if any, force to the hit.
Keep in mind that at this time (late in the swing) you have already turned the shoulders and the arms are bringing the hitting implement into the contact area.By having a late drive off the legs, you do not start the swing with the generation of force that can be transferred into each sequential joint action. Force that can be transferred must be initiated early in the swing.
Driving the hips forward at the beginning of the power phase can be a substantial force especially when combined with a hip turn as the forward hip drive is diminishing. This is known as clearing the hips or getting the hips into the hit or swing. It sets you up for maximum production of force in the following torso and upper limb actions.
Some of the best golfers, baseball hitters and tennis groundstroke players are classic examples of getting the hips cleared early in the swing before the arms begin their action. However, keep in mind that the arms may be in motion because the shoulders bring them around. This does not mean that they initiate the arm action since it happens later when the shoulders are concluding their power phase actions.
For more information on the hip drive and weight shift in golf see Explosive Golf. For more information on the hip drive and weight shift in baseball see Build a Better Athlete.
For more information on the hip drive and weight shift in tennis see Explosive Tennis: The Forehand and Backhand CD.