[dkerby]

V.J. Trolio has a some very interesting comments about
the force: "As you turn and move left, placing the center
of mass over the left leg, the head will go down, the left
knee will increase flex, and a force will be felt into the
ground under the left foot. This is longitudinal force.
Once the force is in the ground (martial arts calls this
rooting) then the instep of the right foot and the large
muscles of the left leg and gluts are used to create sheer
forces (forces that run parrallel to the surface of the
ground) for extreme rotational ability. Whit that said, make
sure you feel the downward rooting into the ground."