In a rowing shell when the rower reaches the finish/recovery part of the stroke, the boat bounces downward in the water absorbing this shock. On an indoor rowing machine, the downward shock, measured at 8 to 25 pounds per stroke, is absorbed in the rower's back since the erg frame sits rigidly on the floor. Even ergs with horizontal slides cannot absorb this axial compression.
 
The Shox-Box allows the ergometer to move vertically diverting that shock from the spine into the Shox-Box enabling the rower to train with less trauma.  With even as little as a 10 pound downward shock on every stroke, approximately 220 strokes, throughout a 2000 meter piece the rower will divert over 2000 pounds (1 Ton) of accumulated trauma to their back with the Shox-Box.