Parsvottanasana w/ chair

From Tadasana, jump into Utthita Hasta Padasana (extended arms and legs), feet 4 to 4-1/2 feet apart. Take hands on the waist. Turn the left foot deeply in and turn the right foot out 90 degrees. Rotate the hips to face the right leg. Keeping the legs straight and steady, inhale and raise the spine, abdomen, chest, sternum and head.  Curve the neck and look up and back.  Bring the head back to center.  Exhale, stretch the entire truck forward to become parallel to the floor. Release hands from the waist and lengthen arms onto the chair seat.  Grasp the rear of the chair seat.  See that both legs remain straight, and continue extending the arms straight.  Keep the pelvis parallel with the floor, raise the head, concave the back and look forward toward the hands.  Move the shoulders toward the hips as you extend the sternum forward. Stay for 30-60 seconds, inhale, return hands to waist and come up, turn the feet forward and join the legs.  Repeat on the left side.  

This asana relieves stiffness in the legs and hip muscles, making the hip joints and spine strong and elastic. One learns to bend forward giving a forward extension to the spinal muscles.  One must learn to make the back concave in order avoid compression of the spinal muscles.  Apart from concavity in the back, the arm and shoulder action improves the structure of the body.  --Yoga In Action: Preliminary Course, Geeta Iyengar