The Boat Pose (Paripurna Navasana)

Strengthens and tones the abdomen, legs and back.
Improves balance.
Tones the intestines.
Limbers the lega and hips.
Begin in a seated postition with your legs lengthened in front of you on the floor.  On an exhale, lean back and begin to raise your legs.  You may need to hold on to the back of the legs or place your hands on the floor behind you for support.  You may need to keep your legs bent until you are strong enough to lengthen them.  Your hands may be on the floor behind you, supporting your legs, or extended by the sides of your legs.  If you have the flexibility, you may hold onto your toes and go into the full version of the pose.  You may repeat this pose 2 -3 times to strenthen your back and abdominal muscles.  Please remember to breathe while holding the pose.

If you are straining while doing this pose, hold the pose for a shorter time and rest for a few breathes in between repeating the pose.  Be sure to take care of your body and do each pose with caution while listening to what your body has to say

source.http://christina-farrell.blogspot.com