At the Gray Institute, the proper sequence of loading into and exploding out of the Transformational Zone (TZ) requires Proximal Acceleration Load (PAL), where the proximal bone segments accelerate while the distal segments are still loading. Possibly just as important is a sequence that is called Proximal Deceleration Whip (PDW).  PDW can be seen in certain sports activities at “the moment of truth” when the intended activity occurs (hitting, throwing, kicking). During this sequence the proximal bone segments decelerate to create a kinetic whip of the distal segments.

To gain a basic appreciation of the biomechanics of PDW, think about an actual whip.  In order to make the whip “snap”, the forward movement of the hand must be followed by a rapid deceleration.  Without the rapid deceleration at the correct time, there is no “snap”.

Looking at the golf swing, the PAL occurs when the pelvis (supported by the legs and feet) starts forward towards the target while the club still moving back.  As the explosion out of the TZ, the weight shifts over to the front leg and PDW begins.  The front leg acts as a post or pivot around which the trunk, arms, and club will rotate.  The pelvis slows down as the front leg “posts”.  As one bone segments decelerates, the next one accelerates then decelerates, creating the whip at the end of the kinetic chain.  If the deceleration sequence does not occur the movement will be inefficient at best, and ineffective (unsuccessful) at worst.

There are many examples of the front leg moving and then planting to allow the whip to occur. Consider the front leg in a baseball hitter or a baseball pitcher.  The front leg plants and the whip begins.  A javelin, discus, or hammer thrower will demonstrate the PDW to maximize the power of the throw.

PDW is harder to see in other sports and movements.  In tennis during the serve and some groundstrokes, when the feet are off the ground it seems that the pelvis must decelerate to create maximum racket head speed.  What about running?  Is the acceleration of the pelvis followed by a rapid deceleration in order to whip the leg through?  Further analysis of all functional movements will likely demonstrate some form of PDW. The importance of sequencing in both PAL and PDW is matched by the need for practitioners to identify and eliminate any barriers to movement in any of the 3 planes.  Once barriers are eliminated, training exercises must progress to movements that utilize authentic drivers.  Using drivers that match the real movement allows the proprioceptors in all the tissues to “recognize” the proper sequences. To enhance your abilities to identify barriers and create authentic training programs consider becoming certified in 3DMAPS and CAFS.