Stuart McGill, professor of spine biomechanics at the University of Waterloo in
Canada has conducted dozens of studies replicating the movement of the
spine when doing this movement.
After replicating the flexing of the human spine, he examined the
discs and found they had been squeezed to the point where they bulged.
THIS Movement presses on nerves causing back pain,
and can even cause a herniated disc.
Watch out for this,
Joel
P.S. Your spine has a shelf life.