PREPARATION
1.Lie on your back with you knees
  bent and feet flat on the floor.

2.Place your hands behind your
  head.

3.Tilt your pelvis forward, so
  your lower back is pressed
  against the floor. Breathe in.

EXERCISE
1.Breathe out as you raise your
  shoulders clear of the floor and
  bend your upper body round to
  the right. Extend your right
  hand to touch your right ankle.

2.Breathe in as you straighten
  your body and return your hand
  to behind your head.

3.Breathe out as you bend your
  upper body round to the left.
  Extend your left hand to touch
  your left ankle.

4.Breathe in as you straighten
  your body and return to the
  start position.

MAINLY FOR: External obliques.