Cobra :: Bhujanagasana
This pose is a great back strengthener and also helps to relieve menstrual difficulties and constipation by massaging the abdominal organs. This pose should be gradually worked into. Don’t go right into the full cobra, but instead allow your spine to stretch gradually and supply upward and backward like a snake.
A common error is to 'shrug' your shoulders. Keep your shoulders down by contracting your back to pull the scapulae downward. Keep your elbows close to your sides. Try to avoid pushing with your arms, but instead use your back muscles to arch your head back.
Don't allow your back to compress. Press your hips into the ground and contract your inner thighs. Press the tops of your feet into the ground to help relax your back muscles. Use your back to lift the pose and the arms to support it.
Have patience and practice this pose every day. Eventually your flexibility will improve. Patience and persistence will get you there.
Namaste.