PREPARATION
1.Lie on your back with your hands
  at your sides and legs straight.

2.Tilt your pelvis slightly
  forward so that your back is
  pressed against the floor.

3.Raise your feet a few
  centimetres from the floor.

4.Keeping both feet clear of the
  floor, raise one foot to about
  half a metre.

EXERCISE
1.Lower the top leg and raise the
  other leg.

2.Continue to alternate the legs
  in a "flutter kick" fashion.

Breathe normally throughout the
exercise.

MAINLY FOR: Lower Abdominals