No specific link of the golf swing can be singled out as more important than any other. Your swing is only as strong as your weakest link, however. During the golf swing, the transfer of energy and power from the lower body to the upper body is the most pivotal link and the most common weakness observed in recreational golfers.
The role of the trunk musculature in the golf swing is much like the role of the crankshaft in automobile performance. Just as the crankshaft turns power created by the pistons into torque at the drive wheels, the trunk musculature turns power created by the lower body into torque at the upper body, which in turn creates club head speed. With maximum energy transfer comes maximum power.
During a right-handed golfer's backswing, the hip and shoulder segments rotate clockwise around the orientation of the spine. As this occurs, trunk musculature that connects the hip and shoulder segments begins to load as a result of the coiling action.
This is important because the energy stored in the muscles during the loading process will help accelerate the shoulders during the swing. Even more important, however, is the dynamic interaction of the hip and shoulder segments. In other words, it is not just how much coil, but the timing and sequence that creates maximum power.
Maximum power is generated in the golf swing when the action of the lower body generates a counterclockwise acceleration of the hips around the axis of the spine. The hip segment accelerates first, creating a dynamic loading of the trunk musculature.
The shoulder segment then follows the lead of the hip segment in a counterclockwise direction and accelerates. At this time the hip segment begins to decelerate. This action passes energy to the trunk as these muscles contract to accelerate the shoulder segment. The result is the creation of power and rotational speed of the shoulders, about double that of the hips.
The two most common breakdowns in transferring energy from the lower body to the upper body originate with the hip segment. The first of these is called sliding hips, which occurs when the hips move laterally to the left without rotating. No rotational speed is created. This actually diminishes energy that can be passed to the upper body.
In many cases sliding hips also indicate an excessive spine tilt. When the spine tilts, muscles that work to rotate the segments around the axis of the trunk become asymmetrical in that one side shortens and the other side lengthens.
This asymmetry causes inefficient generation of power and can increase stress on the low back and joint structures. The second problem is called spinning hips, which occurs when the golfer forces the hip segment through the swing too quickly. This creates an excessive lag between the lower body and the upper body, and the upper body typically does not catch up.
The trunk musculature therefore is unable to pass energy created by the hip segment rotation to the shoulder segment rotation, which means lost power and slower club head speed.
The desired interaction between hip segment rotation and trunk segment rotation occurs in perfect sequence during the optimal swing. The key to this coordinated action .is a high level of strength and flexibility through the trunk area, especially the muscles that contribute to trunk stabilization and rotary movements.