http://www.youtube.com/watch?v=2V-3KPyboLM&feature=related
Lie face down on the floor,stretch arms overhead and reach,keep
your palms face down,extend your right arm and left leg few
inches off the floor,hold a few seconds,lower the arm and the leg
and repeat with the left arm and the right leg ,do 10 repetitions.
This pose strengthens the back muscles,lengthens the spine and
improves balance.